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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Toshiba RPTV 50H72 - blue screen only
This TV only shows blue screen. When I go into setup, I can see that
red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#2
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Toshiba RPTV 50H72 - blue screen only
There may be a loss of sync to the scan circuits, or there may be a response
problem in the video path, thus not allowing proper sync. You would have to get the service manual, and trace through with a scope to see where this type of fault is. Also, checking for the proper supply voltages in the various stages would be a proper thing to do. If you are not trained and equipped in TV service, I would suggest to have the set properly looked after. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm ========================================= "bharat" wrote in message om... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#3
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Toshiba RPTV 50H72 - blue screen only
Ditto on the find someone who knows what they are doing.
This statement (typo fixed) clearly indicates a total lack of understanding of what is going on inside the set: " I think video amps that drive yokes are suspect." David "Jerry G." wrote in message ... There may be a loss of sync to the scan circuits, or there may be a response problem in the video path, thus not allowing proper sync. You would have to get the service manual, and trace through with a scope to see where this type of fault is. Also, checking for the proper supply voltages in the various stages would be a proper thing to do. If you are not trained and equipped in TV service, I would suggest to have the set properly looked after. -- Greetings, Jerry Greenberg GLG Technologies GLG ========================================= WebPage http://www.zoom-one.com Electronics http://www.zoom-one.com/electron.htm ========================================= "bharat" wrote in message om... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#4
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Toshiba RPTV 50H72 - blue screen only
"David" wrote in message ...
Ditto on the find someone who knows what they are doing. This statement (typo fixed) clearly indicates a total lack of understanding of what is going on inside the set: " I think video amps that drive yokes are suspect." This newsgroup is for help. If you cannot provide any help, please stay off the line. If I knew what was wrong, I would not have posted the article in the first place. There was a post previously in this newsgroup where the person was seeing all green screen...the hints were for checking the video amps. So I assumed that would be a first place to start. Your typo-corrected sentence is same as mine. May be you should get some education before getting on the net, you !@#$%^! Send me your email address and we can take this discussion about your intelligence and mine off the newsgroup. bharat |
#5
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Toshiba RPTV 50H72 - blue screen only
So what is an apms?
It still is clear in your posting that you have no clue how a tv set or rptv works. We just went through court because someone idiot bought a part from us (we looked up the part number at his request) and the idiot wound up catching the tv and house on fire!!!!! So he tried to sue us!!! So don't go telling me that you think you know what you are doing when it is clear in your post that you do not. Assuming what you said was video amps, video amps do not drive yokes, period. "bharat" wrote in message om... "David" wrote in message ... Ditto on the find someone who knows what they are doing. This statement (typo fixed) clearly indicates a total lack of understanding of what is going on inside the set: " I think video amps that drive yokes are suspect." This newsgroup is for help. If you cannot provide any help, please stay off the line. If I knew what was wrong, I would not have posted the article in the first place. There was a post previously in this newsgroup where the person was seeing all green screen...the hints were for checking the video amps. So I assumed that would be a first place to start. Your typo-corrected sentence is same as mine. May be you should get some education before getting on the net, you !@#$%^! Send me your email address and we can take this discussion about your intelligence and mine off the newsgroup. bharat |
#6
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Toshiba RPTV 50H72 - blue screen only
Get the flippin set to a Qualified Service Company or consider replacing it
with a new one. It is perfectly obvious that you do not have the qualifications to be attempting to service this product competently. Do yourself a BIG Favor and have it done by the folk who do know how to do it efficiently and safely. "bharat" wrote in message om... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#7
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Toshiba RPTV 50H72 - blue screen only
On Sun, 2 May 2004 15:16:46 -0400, "Art" wrote:
Get the flippin set to a Qualified Service Company or consider replacing it with a new one. It is perfectly obvious that you do not have the qualifications to be attempting to service this product competently. Do yourself a BIG Favor and have it done by the folk who do know how to do it efficiently and safely. Agreed. Pay a little now, or a lot later. That's an excellent TV - it's worth a couple bucks to get it repaired. Alan Harriman "bharat" wrote in message . com... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#8
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Toshiba RPTV 50H72 - blue screen only
Wow, I have never seen so many arrogant people in one newsgroup at the same
time. If you can't help, then just don't say anything. "Art" wrote in message ... Get the flippin set to a Qualified Service Company or consider replacing it with a new one. It is perfectly obvious that you do not have the qualifications to be attempting to service this product competently. Do yourself a BIG Favor and have it done by the folk who do know how to do it efficiently and safely. "bharat" wrote in message om... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#9
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Toshiba RPTV 50H72 - blue screen only
We are helping him. If someone clearly has no clue what is going on, they
are probably going to do one of two things when they attempt to repair something as complex as a tv set: 1. damage it beyond reasonable and practical repair when they finally take it into someone qualified. or 2. Get into something they shouldn't have and cause some potentially lethal or serious injury to themselves. "Eugen T" wrote in message .. . Wow, I have never seen so many arrogant people in one newsgroup at the same time. If you can't help, then just don't say anything. "Art" wrote in message ... Get the flippin set to a Qualified Service Company or consider replacing it with a new one. It is perfectly obvious that you do not have the qualifications to be attempting to service this product competently. Do yourself a BIG Favor and have it done by the folk who do know how to do it efficiently and safely. "bharat" wrote in message om... This TV only shows blue screen. When I go into setup, I can see that red and green CRTs are working (I see green and red colors) but the screen background stays blue. When I connect a DVD player, the screen briefly shows real picture but then turns completely blue. Ditto when I turn the TV off with DVD running (picture shows for an instant before TV turns OFF). I think video apms that drive yokes are suspect..but wanted to confirm with someone before I order the ICs and replace them. I checked all power supplies and they are OK (specially to the video amp ICs). All components I checked seem fine (atleast the ones I checked showed appropriate behavior). Any suggestions are appreciated. bharat |
#10
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Toshiba RPTV 50H72 - blue screen only
Let me make a few things clear to answer your !@#$%^&*() arrogance.
Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
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Toshiba RPTV 50H72 - blue screen only
Video amps are video amplifiers located in Q751 and Q752 on the signal
board. They drive yokes directly. Video amplifiers do not drive yokes. Deflection circuitry drives = deflection yokes. I have a PhD in electrical enginnering also, but not = the attitude you have. David |
#12
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Toshiba RPTV 50H72 - blue screen only
David wrote: Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. Video amplifiers do not drive yokes. Deflection circuitry drives deflection yokes. I have a PhD in electrical enginnering also, but not the attitude you have. David Hi... Darn, you guys are embarassing me. I only got to bachelor, and that only by the skin of my teeth. (Hey, someone had to finish at the bottom of the class, right? Now old, long retired, and a stroke victim. Spent a year couldn't walk, and a few years wondering who I was and why. I continue to get better, though, and can help a little here. I agree that it's a problem with the synchronization of his yokes. I suspect that his blue yoke has gone out of sync, and he's going to have to replace it. A quick test to verify this would be to temporarily switch the red and blue yoke (or the green and blue yoke) just to see if it improves. If it does, just call Toshiba or one of it's dealers and order a new blue yoke. Ken |
#13
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Toshiba RPTV 50H72 - blue screen only
David is completely correct, video amps don't drive yokes. I suppose they
didn't teach you that in electrical engineering. Actually, Q751 and Q752 are convergence amplifiers, not video amplifiers, and are likely not your problem. If one of these failed you would see convergence problems, the set would shut down, or it would blow fuse(s) and shut down. If you are getting a blue screen it is likely that you have lost signal and the set is muting the video. Your problem could be anything from not knowing how to operate the set to a problem anywhere in the signal path. If you are looking for video amplifiers you are looking in the wrong area. You might want to check your assumptions and your reading of the schematic before losing it on a forum where you are asking for help. Your post indicated exactly what David noted, that you may be in over your head. Now, if you want some help, why not tell us what equipment you have, and what measurements you have taken and the signal conditions under which they were taken. A few of us arrogant morons, as you put it, have quite a lot of experience that we might be willing to share. Understand, however, that if you don't have the right equipment, knowledge, and troubleshooting skills, this may not be a realistic repair for you to attempt. Your attitude and your PhD will not necessarily help in fixing your set. A scope, some humility, and some TV service skills would go a lot farther. Leonard Pedantic asshole, maybe...arrogant moron, not usually "bharat" wrote in message om... Let me make a few things clear to answer your !@#$%^&*() arrogance. Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
#14
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Toshiba RPTV 50H72 - blue screen only
Absolute WASTE OF MY TIME!!! This flippin bloke is helpless, ignorant,
stupid and don't even realize it. Blantely obvious he does not want assistance since he bloody knows everything about this device. Cheere, Mate, have a good live as and Electrical Engineer. I hope I never encounter any device you had any interest in designing or implimenting. "Leonard G. Caillouet" wrote in message . .. David is completely correct, video amps don't drive yokes. I suppose they didn't teach you that in electrical engineering. Actually, Q751 and Q752 are convergence amplifiers, not video amplifiers, and are likely not your problem. If one of these failed you would see convergence problems, the set would shut down, or it would blow fuse(s) and shut down. If you are getting a blue screen it is likely that you have lost signal and the set is muting the video. Your problem could be anything from not knowing how to operate the set to a problem anywhere in the signal path. If you are looking for video amplifiers you are looking in the wrong area. You might want to check your assumptions and your reading of the schematic before losing it on a forum where you are asking for help. Your post indicated exactly what David noted, that you may be in over your head. Now, if you want some help, why not tell us what equipment you have, and what measurements you have taken and the signal conditions under which they were taken. A few of us arrogant morons, as you put it, have quite a lot of experience that we might be willing to share. Understand, however, that if you don't have the right equipment, knowledge, and troubleshooting skills, this may not be a realistic repair for you to attempt. Your attitude and your PhD will not necessarily help in fixing your set. A scope, some humility, and some TV service skills would go a lot farther. Leonard Pedantic asshole, maybe...arrogant moron, not usually "bharat" wrote in message om... Let me make a few things clear to answer your !@#$%^&*() arrogance. Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
#15
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Toshiba RPTV 50H72 - blue screen only
By The Way, the typos are intentional!! Maybe he just understands Phonics??
"Art" wrote in message ... Absolute WASTE OF MY TIME!!! This flippin bloke is helpless, ignorant, stupid and don't even realize it. Blantely obvious he does not want assistance since he bloody knows everything about this device. Cheere, Mate, have a good live as and Electrical Engineer. I hope I never encounter any device you had any interest in designing or implimenting. "Leonard G. Caillouet" wrote in message . .. David is completely correct, video amps don't drive yokes. I suppose they didn't teach you that in electrical engineering. Actually, Q751 and Q752 are convergence amplifiers, not video amplifiers, and are likely not your problem. If one of these failed you would see convergence problems, the set would shut down, or it would blow fuse(s) and shut down. If you are getting a blue screen it is likely that you have lost signal and the set is muting the video. Your problem could be anything from not knowing how to operate the set to a problem anywhere in the signal path. If you are looking for video amplifiers you are looking in the wrong area. You might want to check your assumptions and your reading of the schematic before losing it on a forum where you are asking for help. Your post indicated exactly what David noted, that you may be in over your head. Now, if you want some help, why not tell us what equipment you have, and what measurements you have taken and the signal conditions under which they were taken. A few of us arrogant morons, as you put it, have quite a lot of experience that we might be willing to share. Understand, however, that if you don't have the right equipment, knowledge, and troubleshooting skills, this may not be a realistic repair for you to attempt. Your attitude and your PhD will not necessarily help in fixing your set. A scope, some humility, and some TV service skills would go a lot farther. Leonard Pedantic asshole, maybe...arrogant moron, not usually "bharat" wrote in message om... Let me make a few things clear to answer your !@#$%^&*() arrogance. Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
#16
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Toshiba RPTV 50H72 - blue screen only
You are still totally clueless. Talk about a worthless phd if you really
have one, which I doubt given the new post where you try and prove that you know what you are talking about. Not even close again. Q751 and Q752 are not video amps. (at least you spelled it correctly this time). They are AUDIO amplifier output ic's being used as convergence output amplifiers. I totally understood the posting and the fact that you did not understand electronics enough to try and attempt a repair. It is even more clear that you have no business whatever your so called worthless paper degree is in to be inside the tv attempting a repair on it. Especially since you cannot read or spell, (apms vs amps, not the same thing dumbass) doubtful you have any college degree. I pity the reputation of any college that actually gave you a degree. At least you did not try and call it 'snyc' this time around. "bharat" wrote in message om... Let me make a few things clear to answer your !@#$%^&*() arrogance. Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
#17
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Toshiba RPTV 50H72 - blue screen only
If you only knew how sub-standard some college education really is these
days, you would laugh. Some words of wisdom from my Father who hired engineers: Those that can do, those that can't teach. Never ever hire an engineer that was not a technician first, they cannot troubleshoot thier way out of a paperbag. "Art" wrote in message ... By The Way, the typos are intentional!! Maybe he just understands Phonics?? "Art" wrote in message ... Absolute WASTE OF MY TIME!!! This flippin bloke is helpless, ignorant, stupid and don't even realize it. Blantely obvious he does not want assistance since he bloody knows everything about this device. Cheere, Mate, have a good live as and Electrical Engineer. I hope I never encounter any device you had any interest in designing or implimenting. "Leonard G. Caillouet" wrote in message . .. David is completely correct, video amps don't drive yokes. I suppose they didn't teach you that in electrical engineering. Actually, Q751 and Q752 are convergence amplifiers, not video amplifiers, and are likely not your problem. If one of these failed you would see convergence problems, the set would shut down, or it would blow fuse(s) and shut down. If you are getting a blue screen it is likely that you have lost signal and the set is muting the video. Your problem could be anything from not knowing how to operate the set to a problem anywhere in the signal path. If you are looking for video amplifiers you are looking in the wrong area. You might want to check your assumptions and your reading of the schematic before losing it on a forum where you are asking for help. Your post indicated exactly what David noted, that you may be in over your head. Now, if you want some help, why not tell us what equipment you have, and what measurements you have taken and the signal conditions under which they were taken. A few of us arrogant morons, as you put it, have quite a lot of experience that we might be willing to share. Understand, however, that if you don't have the right equipment, knowledge, and troubleshooting skills, this may not be a realistic repair for you to attempt. Your attitude and your PhD will not necessarily help in fixing your set. A scope, some humility, and some TV service skills would go a lot farther. Leonard Pedantic asshole, maybe...arrogant moron, not usually "bharat" wrote in message om... Let me make a few things clear to answer your !@#$%^&*() arrogance. Video amps are video amplifiers located in Q751 and Q752 on the signal board. They drive yokes directly. In case any of you arrogant morons had time and knowledge to understand what a schmatic looks like, you would clearly see where video amplifiers are located. In adition, amps is shorthand for amplifiers - any person knowledgable in Electrical Engineering knows that. Next time, try to understand the posting before replying. Your assumption that if you do not understand something then it must be wrong is stupid! Secondly, a while back in this newsgroup, there was a posting where someone had green screen problem similar to mine. The solution posted on the net was that the power supply to video amplifiers was suspect. Hence my intuition regarding video amps (oops, I mean video amplifiers for you intellectually-challenged guys). Many of us know and understand the danger in repairing a TV set - not just you arrogant !@$$%&*. By the way, I have a PhD in electrical engineering and probably can run circles around you when it comes to knowledge of electrical engineering. However, I do not know specifically how to fix a TV and hence the posting. If I had the time, I can understand the circuit and then figure out what is wrong. I was hoping that this newsgroup, with its collective knowledge, will help me fix this. Your arrogant replies regarding "what is amps" itself shows that you do not have a clue as to what an "amplifier" is. Take a few educational courses (or read a book) before you start yelling at people. Again, this newsgroup is for help. If you can help, please by all means do so. If you do not understand what an "amps" is, do everyone a favor and stop wasting bandwidth. By the way, I am going to check the sync signals (for you stupids, it is synchronization signals) to see if the problem lies there as pointed out by more considerate members of this newsgroup. I thank them. bharat |
#18
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Toshiba RPTV 50H72 - blue screen only
I haven't had this many arguments over a posting for a long time!!:-)
I own another 52H72 and have troubleshot the power board without any problem (it did take me a whole weekend to do it). That set kept turning on and off. I was hoping to avoid a repeat of my "lost" weekend. I wanted someone to point out the area I should be checking. I am not that familiar with the signal board and I believe people on the net have more experience than I will ever have repairing a TV. Hence the post. I did not want to post a lengthy note on what tests I did (I checked all power supply lines, H-sync, and yoke drivers. I have multimeters and a simple oscilloscope). I went through the schematic. Went through this newsgroup. A previous post mentioned video amps. There were amplifiers driving the yokes. I assumed that is what the previous message was talking about when it said video amps. If I was wrong, please point it out and point me in the correct direction. Pointing out my inexperience in repairing a TV is acceptable, but not providing help and flaming me is not OK. There are hundreds of postings each day here. If you can't provide help, don't say anything. Everyone who reads this newsgroup knows (a) a lot of novices are attempting TV repair who should not, (b) TV repair is dangerous business, (c) most of these novices will harm themselves (darwinian principle at work) and learn along the way not to do it again (as David's post pointed out about the guy who burned his house down). Please do not assume that someone is not capable of understanding things regarding TV and repairing it. With a little help and some precautions (and common sense about electrical engineering), competent people can repair TVs. Newsgroups like this one certainly helps. I did not mean to offend collectively everyone (I was thinking no one will read this posting because it was old. And only David and I will scream at each other for a day and then forget about it). Obviously that is not the case. I am going to check yokes and sync signals. Hopefully, that will tell me more about where to go. Thanks for all the help. bharat |
#19
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Toshiba RPTV 50H72 - blue screen only
bharat wrote: I haven't had this many arguments over a posting for a long time!!:-) I own another 52H72 and have troubleshot the power board without any problem (it did take me a whole weekend to do it). That set kept turning on and off. I was hoping to avoid a repeat of my "lost" weekend. I wanted someone to point out the area I should be checking. I am not that familiar with the signal board and I believe people on the net have more experience than I will ever have repairing a TV. Hence the post. I did not want to post a lengthy note on what tests I did (I checked all power supply lines, H-sync, and yoke drivers. I have multimeters and a simple oscilloscope). I went through the schematic. Went through this newsgroup. A previous post mentioned video amps. There were amplifiers driving the yokes. I assumed that is what the previous message was talking about when it said video amps. If I was wrong, please point it out and point me in the correct direction. Pointing out my inexperience in repairing a TV is acceptable, but not providing help and flaming me is not OK. There are hundreds of postings each day here. If you can't provide help, don't say anything. Everyone who reads this newsgroup knows (a) a lot of novices are attempting TV repair who should not, (b) TV repair is dangerous business, (c) most of these novices will harm themselves (darwinian principle at work) and learn along the way not to do it again (as David's post pointed out about the guy who burned his house down). Please do not assume that someone is not capable of understanding things regarding TV and repairing it. With a little help and some precautions (and common sense about electrical engineering), competent people can repair TVs. Newsgroups like this one certainly helps. I did not mean to offend collectively everyone (I was thinking no one will read this posting because it was old. And only David and I will scream at each other for a day and then forget about it). Obviously that is not the case. I am going to check yokes and sync signals. Hopefully, that will tell me more about where to go. Thanks for all the help. bharat Hi... Seeing as this message is a tiny bit apologetic, and a lot less arrogant, I'll take a chance and try again... hopefully a little has been learned (on both sides) and a fresh start is possible. I'll apologize for my message agreeing (sarcastically) with you, and hope we can do better. So, having said that, I'm an old stroke damaged retired guy who hasn't been in the picture for several years... just keeping in touch, so don't take my word either as gospel, or current What got everyone's dander up started with the yoke. The yoke has absolutely nothing, repeat nothing to do with your current problem. The yoke is that round coils of wire on the neck of the picture tube, pushed snugly up against the "flare" of the tube. It's sole purpose in life is deflection. It's driven by the horizontal and vertical ouputs. If the horizontal portion fails, you'll be left with (theoretically only) a bright white vertical line. If the vertical fails, you'll be left with (in reality) a straight white horizontal line across the center of the crt. So, let's leave the yoke out of it. Sync is responsible for synchronizing that vertical and horizontal deflection... failure will give you a "rolling" picture (vertical fail) or one that won't "stand straight up. So let's leave sync out of it. What have we left that IS perhaps responsible? Well, there is a possibility that the blue grid in the crt is shorted. This almost certainly makes the set not worth repair. There are drivers (transistors), one for each colour. These are most likely located on the pcb which is plugged onto the picture tube socket. The possiblity is that one is shorted. Check them easily enough by simply comparing them one against another with the other "set" Further than that I cannot go, not knowing your set or even much of the state of the art. But it's a start in the right direction, and perhaps can lead to more. I'll take a chance and give you one tiny little lecture and life lesson. I raised many kids, (all girls) and now am an old man all alone raising (trying) a just turned teenage grand daughter. I told each of them, and now I tell you, that how you treat other people is going to make a bigger difference in you life than any other thing you can do. More important than education, than skills, than wealth, than appearance, anything. Let's see where we go from here. Good luck, and take care. Ken |
#20
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Toshiba RPTV 50H72 - blue screen only
Answer these questions and you might be able to narrow it down.
Do you have a schematic? When the picture appears, does the color look good for the second? If so the tv is probably going into blue screen mute. Look to the system control (aka microcontroller/ micro) ic that basically runs everything first. You will may find OSD outputs RGB going to the jungle ic (term for the big signal process ic that does most everything). Look at the RBG outputs to see if the blue is on (more or less) all the time. If it is the micro is definitely putting the tv into blue screen mute. Then look for the signal sync going into the micro to see if it is present. The micro has several must signals in order to display a picture. H-sync (horizontal feedback sync from deflection) set will usually turn off if missing right away, V-Sync (vertical feedback sync from deflection) tv will typically shut down after 2 to 3 seconds, 60Hz clock signal from the ac power line (different sets behave strangely, could cause blue screen mute), a serial clock and data handshake from several other ics on the databus (since manufactures do not provide enough information to actually troubleshoot this, swap a part until it works, some tv sets have a computer interface and error code service mode to help), of course the micro needs the signal sync in order to know there is an image to display, we cannot forget about the AKB (auto-kine-bias) circuits on the picture tubes which can blank the video completely. Simple troubleshooting: 1. Since the menu works, and if the audio goes up and down, or different video inputs can be selected via the remote control. This indicates that at least the data buss is functional and the ics are communications. It does not mean there not an ic that is not sending the all ok signal to the micro however. 2. Since the video comes on for a second when immediately switching inputs, the set is most likely in blue screen mute. 3. If the blue screen does not have the 10-12 visible diagonal retrace lines, this pretty much rules out the video output stages. 4. Try the s-video or component inputs to see if they work as well. If the s-video works, it means there is a problem before or including the comb filter. If only the component video works even more of the signal circuit has been eliminated. 5. Do not forget that this device has virtually all of its functional parameters (adjustments) set by an eeprom and service menu. Corrupted data in the wrong location can cause the same symptoms as actual parts failures. As an added note, I strongly recommend you use an isolation transformer for the tv set whenever working on it with the back removed. It will provide a level of safety to yourself and your test equipment that no measure of being careful can achieve. Even though that set uses a SMPS to provide isolation, there are still exposed components and traces tied directly to the AC power line source. After doing some research, I found out you really are at least a Professor at a college or university so you might have a PhD afterall, sorry for doubting your word. Don't take anything personal as it is hard to judge the character of someone from inaccurate information posted on the web. I have to go by experience and it has not been a good one with some people, as indicated with the fire and lawsuit. I have taught unemployed engineers in a course where they were retraining to become technicians. They were by far the worst students at "getting it" when it came to real world troubleshooting and circuit behavior. It should take about 15 minutes maximum to narrow down a close location of the problem. I always check the required stuff before going in very deep. Proper and clean Vcc and Vdd votlages. All the correct signals to the system control, 60Hz ac pulse, H-sync, V-sync, Signal sync, clean Vcc, etc. Then move to the jungle ic. If the Signal sync is found missing or small, simply start tracing it back to its source (near the jungle ic I am sure). "bharat" wrote in message om... I haven't had this many arguments over a posting for a long time!!:-) I own another 52H72 and have troubleshot the power board without any problem (it did take me a whole weekend to do it). That set kept turning on and off. I was hoping to avoid a repeat of my "lost" weekend. I wanted someone to point out the area I should be checking. I am not that familiar with the signal board and I believe people on the net have more experience than I will ever have repairing a TV. Hence the post. I did not want to post a lengthy note on what tests I did (I checked all power supply lines, H-sync, and yoke drivers. I have multimeters and a simple oscilloscope). I went through the schematic. Went through this newsgroup. A previous post mentioned video amps. There were amplifiers driving the yokes. I assumed that is what the previous message was talking about when it said video amps. If I was wrong, please point it out and point me in the correct direction. Pointing out my inexperience in repairing a TV is acceptable, but not providing help and flaming me is not OK. There are hundreds of postings each day here. If you can't provide help, don't say anything. Everyone who reads this newsgroup knows (a) a lot of novices are attempting TV repair who should not, (b) TV repair is dangerous business, (c) most of these novices will harm themselves (darwinian principle at work) and learn along the way not to do it again (as David's post pointed out about the guy who burned his house down). Please do not assume that someone is not capable of understanding things regarding TV and repairing it. With a little help and some precautions (and common sense about electrical engineering), competent people can repair TVs. Newsgroups like this one certainly helps. I did not mean to offend collectively everyone (I was thinking no one will read this posting because it was old. And only David and I will scream at each other for a day and then forget about it). Obviously that is not the case. I am going to check yokes and sync signals. Hopefully, that will tell me more about where to go. Thanks for all the help. bharat |
#21
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Toshiba RPTV 50H72 - blue screen only
Now I am happy!!! And I agree I have a lot to learn about TV repair.
But with the help from the 'net, I should be able to get this one working. Hopefully, I won't need to repair another one for a while. Thanks to everyone who posted help. I replaced the bad signal board with one from the functioning set. The TV worked fine. Based on the hints from David and Ken, I think the TV is going into Blue screen mute mode (the picture looks fine whenever I could see it). I will check it based on responses from Ken and David and see if I can get it working this weekend. Sorry I lost my mind there earlier. When David posted that note saying I do not have any business doing repairs on electronic systems, it got my professional "ego" hurt (I guess) (specially because he did not provide any help in that posting. In retrospect, he WAS proving help by making sure I do not electrocute myself - without knowing my background. But at the time, it didn't sound nice). I also understand from Ken's posting why my statements would not make much sense. I should have just stayed away from making any comments and just asked for help. It would have saved a lot of bandwidth! Live and learn! Another reason for my temper-tantrum (I guess) was my old habits. I used newsgroups extensively when I was a grad student. Then, we did not post anything that was not useful (internet was not available...only a few people had access to newsgroups. Bandwidth was low). I always believed the postings were not for money or fame, but for the satisfaction of helping others (same is true today. If any of you who helped are waiting for a check from me, you will be waiting a long time:-)). When I saw David's post, it just irked me that he was not telling me anything useful (I repeatedly stated in my postings that if you can't help, stay away...I guess old habits die hard!). Anyway, I like this newsgroup. I will start reading it on a regular basis and see if I can provide help. I may not be a good trouble-shooter, but I am a good designer. If you need help in the design area, do drop a line. bharat |
#22
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Toshiba RPTV 50H72 - blue screen only
You old hat knowledge forgets that modern tv sets have something called blue
screen mute when there is no signal. The fact that there are no retrace lines on the blue and a normal picture for a second whenever changing sources 99% rules out a problem with the cathode drive on the blue tube. There is a possibility that a problem with the AKB circuit could be overdriving the blue, but an image would still be visible, but very blue. You are correct in leave the yoke out of it. The sync however does so much more on a modern tv than causing the picture to roll or tear horizontally if those are a problem. Without horizontal or vertical sync pulses to the system control, the tv will shut down to protect the picture tubes. Without the sync pulses to the jungle ic, odds are no on screen display will be visible. The signal sync coming off the luminance is required for the micro to detect the closed captioning information and if missing will likely result in a blue screen mute. bharat: another tip here. If you turn on closed captioning in the user menu since the menu was working, and you select a tv channel that you know is sending closed captioning (use another tv with it turned on to be sure), do you get the closed captioning on screen or just a blank box? If closed captioning is not working, the micro definitely is not seeing the sync pulses off the incoming signal. David "Ken Weitzel" wrote in message news:8PXlc.372803$Ig.110898@pd7tw2no... bharat wrote: I haven't had this many arguments over a posting for a long time!!:-) I own another 52H72 and have troubleshot the power board without any problem (it did take me a whole weekend to do it). That set kept turning on and off. I was hoping to avoid a repeat of my "lost" weekend. I wanted someone to point out the area I should be checking. I am not that familiar with the signal board and I believe people on the net have more experience than I will ever have repairing a TV. Hence the post. I did not want to post a lengthy note on what tests I did (I checked all power supply lines, H-sync, and yoke drivers. I have multimeters and a simple oscilloscope). I went through the schematic. Went through this newsgroup. A previous post mentioned video amps. There were amplifiers driving the yokes. I assumed that is what the previous message was talking about when it said video amps. If I was wrong, please point it out and point me in the correct direction. Pointing out my inexperience in repairing a TV is acceptable, but not providing help and flaming me is not OK. There are hundreds of postings each day here. If you can't provide help, don't say anything. Everyone who reads this newsgroup knows (a) a lot of novices are attempting TV repair who should not, (b) TV repair is dangerous business, (c) most of these novices will harm themselves (darwinian principle at work) and learn along the way not to do it again (as David's post pointed out about the guy who burned his house down). Please do not assume that someone is not capable of understanding things regarding TV and repairing it. With a little help and some precautions (and common sense about electrical engineering), competent people can repair TVs. Newsgroups like this one certainly helps. I did not mean to offend collectively everyone (I was thinking no one will read this posting because it was old. And only David and I will scream at each other for a day and then forget about it). Obviously that is not the case. I am going to check yokes and sync signals. Hopefully, that will tell me more about where to go. Thanks for all the help. bharat Hi... Seeing as this message is a tiny bit apologetic, and a lot less arrogant, I'll take a chance and try again... hopefully a little has been learned (on both sides) and a fresh start is possible. I'll apologize for my message agreeing (sarcastically) with you, and hope we can do better. So, having said that, I'm an old stroke damaged retired guy who hasn't been in the picture for several years... just keeping in touch, so don't take my word either as gospel, or current What got everyone's dander up started with the yoke. The yoke has absolutely nothing, repeat nothing to do with your current problem. The yoke is that round coils of wire on the neck of the picture tube, pushed snugly up against the "flare" of the tube. It's sole purpose in life is deflection. It's driven by the horizontal and vertical ouputs. If the horizontal portion fails, you'll be left with (theoretically only) a bright white vertical line. If the vertical fails, you'll be left with (in reality) a straight white horizontal line across the center of the crt. So, let's leave the yoke out of it. Sync is responsible for synchronizing that vertical and horizontal deflection... failure will give you a "rolling" picture (vertical fail) or one that won't "stand straight up. So let's leave sync out of it. What have we left that IS perhaps responsible? Well, there is a possibility that the blue grid in the crt is shorted. This almost certainly makes the set not worth repair. There are drivers (transistors), one for each colour. These are most likely located on the pcb which is plugged onto the picture tube socket. The possiblity is that one is shorted. Check them easily enough by simply comparing them one against another with the other "set" Further than that I cannot go, not knowing your set or even much of the state of the art. But it's a start in the right direction, and perhaps can lead to more. I'll take a chance and give you one tiny little lecture and life lesson. I raised many kids, (all girls) and now am an old man all alone raising (trying) a just turned teenage grand daughter. I told each of them, and now I tell you, that how you treat other people is going to make a bigger difference in you life than any other thing you can do. More important than education, than skills, than wealth, than appearance, anything. Let's see where we go from here. Good luck, and take care. Ken |
#23
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Toshiba RPTV 50H72 - blue screen only
Does the set still mute the video on ALL sources? 1080i? 480p? 480i? Do
you see any OSD, any PIP/POP? Leonard "bharat" wrote in message om... Now I am happy!!! And I agree I have a lot to learn about TV repair. But with the help from the 'net, I should be able to get this one working. Hopefully, I won't need to repair another one for a while. Thanks to everyone who posted help. I replaced the bad signal board with one from the functioning set. The TV worked fine. Based on the hints from David and Ken, I think the TV is going into Blue screen mute mode (the picture looks fine whenever I could see it). I will check it based on responses from Ken and David and see if I can get it working this weekend. Sorry I lost my mind there earlier. When David posted that note saying I do not have any business doing repairs on electronic systems, it got my professional "ego" hurt (I guess) (specially because he did not provide any help in that posting. In retrospect, he WAS proving help by making sure I do not electrocute myself - without knowing my background. But at the time, it didn't sound nice). I also understand from Ken's posting why my statements would not make much sense. I should have just stayed away from making any comments and just asked for help. It would have saved a lot of bandwidth! Live and learn! Another reason for my temper-tantrum (I guess) was my old habits. I used newsgroups extensively when I was a grad student. Then, we did not post anything that was not useful (internet was not available...only a few people had access to newsgroups. Bandwidth was low). I always believed the postings were not for money or fame, but for the satisfaction of helping others (same is true today. If any of you who helped are waiting for a check from me, you will be waiting a long time:-)). When I saw David's post, it just irked me that he was not telling me anything useful (I repeatedly stated in my postings that if you can't help, stay away...I guess old habits die hard!). Anyway, I like this newsgroup. I will start reading it on a regular basis and see if I can provide help. I may not be a good trouble-shooter, but I am a good designer. If you need help in the design area, do drop a line. bharat |
#24
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Toshiba RPTV 50H72 - blue screen only
None of the sources I checked worked. The screen stays blue. No PIP
either. Video is certainly (as far as I can tell) in blue screen mute mode (never heard of this before...but then I am not an expert on these matters!!!:-)). I haven't checked CC input as per David. I will check it tonight. RGB outputs on jungle IC are not what the manual says they should be (staying HIGH most of the time as David suggested). Last night, I checked the voltages on the sync inputs on micro. The H-Sync node on the micro is supposed to have 3.0V according to the manual and it was showing 2.5 (my kids came back before I could check it on oscilloscope...so had to give up). SCL1 and SDA1 (don't know what these signals are...if you can post something about their function, I will appreciate it) also are supposed to be 4.6V but were showing around 4.0V. All these measurements are DC. Rest of signals were showing expected (as per the schematic) voltages. Can a 0.5V drop on H-sync cause blue_screen mute? I will have to trace that one to see why that is low. Also, I will check all sync signals on oscilloscope to check for proper waveforms. Is micro the only circuit that will cause a blue-screen mute (BSM)? David had listed a lot of reasons for BSM but only micro as the controller for BSM. Another questions I have is how does the menu screen work if sync signals are messed up? I thought all screen functions will be needing sync signals and menu is certainly screen-based. Does this mean sync are OK but something else is causing BSM or are menu sync signals different from normal sync signals? Gotta run....I gave my final and kids are lining up to know their grades and I haven't graded the exams yet!! Why does my posting take a lot longer (at least it seems to me that way) than everyone else's posting? It seems David posted twice before mine even showed up! bharat |
#25
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Toshiba RPTV 50H72 - blue screen only
bharat wrote:
Why does my posting take a lot longer (at least it seems to me that way) than everyone else's posting? It seems David posted twice before mine even showed up! You're posting via Google; David is posting via greennet.net. -- John Miller Email address: domain, n4vu.com; username, jsm Everyone's in a high place when you're on your knees. |
#26
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Toshiba RPTV 50H72 - blue screen only
bharat wrote: None of the sources I checked worked. The screen stays blue. No PIP either. Video is certainly (as far as I can tell) in blue screen mute mode (never heard of this before...but then I am not an expert on these matters!!!:-)). I haven't checked CC input as per David. I will check it tonight. RGB outputs on jungle IC are not what the manual says they should be (staying HIGH most of the time as David suggested). Last night, I checked the voltages on the sync inputs on micro. The H-Sync node on the micro is supposed to have 3.0V according to the manual and it was showing 2.5 (my kids came back before I could check it on oscilloscope...so had to give up). SCL1 and SDA1 (don't know what these signals are...if you can post something about their function, I will appreciate it) also are supposed to be 4.6V but were showing around 4.0V. All these measurements are DC. Rest of signals were showing expected (as per the schematic) voltages. Can a 0.5V drop on H-sync cause blue_screen mute? I will have to trace that one to see why that is low. Also, I will check all sync signals on oscilloscope to check for proper waveforms. Is micro the only circuit that will cause a blue-screen mute (BSM)? David had listed a lot of reasons for BSM but only micro as the controller for BSM. Another questions I have is how does the menu screen work if sync signals are messed up? I thought all screen functions will be needing sync signals and menu is certainly screen-based. Does this mean sync are OK but something else is causing BSM or are menu sync signals different from normal sync signals? Gotta run....I gave my final and kids are lining up to know their grades and I haven't graded the exams yet!! Why does my posting take a lot longer (at least it seems to me that way) than everyone else's posting? It seems David posted twice before mine even showed up! bharat Hi... I believe you'll find that the law calls for ungraded papers to all recieve the default A+, or 4, or 100%; whichever is best in your country. I have one more tiny suggestion if I may? Keep in mind it comes from an "old hat" as David so generously called it I, too, had never seen a blue screen (except for Windows) so played around a little. Big 5 bedroom house for one old man and one little girl, but lots of TV's... All connected to cable boxes. Tried them. Turn the cable box off via remote, and the TV mutes audio, the raster goes very, very dim for about 5 seconds; then the tv automagically shuts off. (seperate ac feeds) One in the basement belongs to my cottage neighbor, waiting for transport to the cottage for fishing season opening tomorrow. Plugged it in - snow and hiss. Stuck a resistor lead into the rf input, poor picture and sound or snow and hiss on all channels. Wondered why the difference, worried over it for a while, and finally found the difference. User menu - choose "cable" or "tv". The sets upstairs set to cable; the one in the basement set to tv. So - is it possible that the set you're working on in the cable position with no cable box? (switching modules would have also switched eproms, might have been different) Worth a shot, anyway. Good luck. Ken |
#27
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Toshiba RPTV 50H72 - blue screen only
I have een some great suggestions.
Here is mine. start over. use your 5 senses. give it an extreme visual inspection, smell the unit, . feel the unit, etc Then, check your power supplies, both main and local, ( in any suspected areas) Get the manual. Use sympton analyisis diagnosis to narrow your troubleshooting. If you have a PIP board, suspect that. (and or component therein) Tuner possibly, and whatever video switching devices/circuits would be suspect as well. Looks like a possible "crap"-acitor hunt ...finals... ...kids... those may play a role good luck |
#28
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Toshiba RPTV 50H72 - blue screen only
Cable mode allows the set to recieve cable frequencies instead of the UHF
that the air or tv mode allows. It has nothing to do with whether the set isconnected to a cable box or not on most sets. Leonard "Ken Weitzel" wrote in message news:cwymc.367400$Pk3.158706@pd7tw1no... bharat wrote: None of the sources I checked worked. The screen stays blue. No PIP either. Video is certainly (as far as I can tell) in blue screen mute mode (never heard of this before...but then I am not an expert on these matters!!!:-)). I haven't checked CC input as per David. I will check it tonight. RGB outputs on jungle IC are not what the manual says they should be (staying HIGH most of the time as David suggested). Last night, I checked the voltages on the sync inputs on micro. The H-Sync node on the micro is supposed to have 3.0V according to the manual and it was showing 2.5 (my kids came back before I could check it on oscilloscope...so had to give up). SCL1 and SDA1 (don't know what these signals are...if you can post something about their function, I will appreciate it) also are supposed to be 4.6V but were showing around 4.0V. All these measurements are DC. Rest of signals were showing expected (as per the schematic) voltages. Can a 0.5V drop on H-sync cause blue_screen mute? I will have to trace that one to see why that is low. Also, I will check all sync signals on oscilloscope to check for proper waveforms. Is micro the only circuit that will cause a blue-screen mute (BSM)? David had listed a lot of reasons for BSM but only micro as the controller for BSM. Another questions I have is how does the menu screen work if sync signals are messed up? I thought all screen functions will be needing sync signals and menu is certainly screen-based. Does this mean sync are OK but something else is causing BSM or are menu sync signals different from normal sync signals? Gotta run....I gave my final and kids are lining up to know their grades and I haven't graded the exams yet!! Why does my posting take a lot longer (at least it seems to me that way) than everyone else's posting? It seems David posted twice before mine even showed up! bharat Hi... I believe you'll find that the law calls for ungraded papers to all recieve the default A+, or 4, or 100%; whichever is best in your country. I have one more tiny suggestion if I may? Keep in mind it comes from an "old hat" as David so generously called it I, too, had never seen a blue screen (except for Windows) so played around a little. Big 5 bedroom house for one old man and one little girl, but lots of TV's... All connected to cable boxes. Tried them. Turn the cable box off via remote, and the TV mutes audio, the raster goes very, very dim for about 5 seconds; then the tv automagically shuts off. (seperate ac feeds) One in the basement belongs to my cottage neighbor, waiting for transport to the cottage for fishing season opening tomorrow. Plugged it in - snow and hiss. Stuck a resistor lead into the rf input, poor picture and sound or snow and hiss on all channels. Wondered why the difference, worried over it for a while, and finally found the difference. User menu - choose "cable" or "tv". The sets upstairs set to cable; the one in the basement set to tv. So - is it possible that the set you're working on in the cable position with no cable box? (switching modules would have also switched eproms, might have been different) Worth a shot, anyway. Good luck. Ken |
#29
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Toshiba RPTV 50H72 - blue screen only
PIP and capacitor problems have not been common issues with this set. This
guy needs to be using a scope at this point. Leonard "r c" wrote in message ... I have een some great suggestions. Here is mine. start over. use your 5 senses. give it an extreme visual inspection, smell the unit, . feel the unit, etc Then, check your power supplies, both main and local, ( in any suspected areas) Get the manual. Use sympton analyisis diagnosis to narrow your troubleshooting. If you have a PIP board, suspect that. (and or component therein) Tuner possibly, and whatever video switching devices/circuits would be suspect as well. Looks like a possible "crap"-acitor hunt ...finals... ...kids... those may play a role good luck |
#30
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Toshiba RPTV 50H72 - blue screen only
Leonard Caillouet wrote: Cable mode allows the set to recieve cable frequencies instead of the UHF that the air or tv mode allows. It has nothing to do with whether the set isconnected to a cable box or not on most sets. Leonard Hi Leonard... Sounds like you might be in the same "old hat" category as me. Give up, you can't win That's the way I remember it too. First uhf which of course was a whole different thing. Then a mechanical switch which allowed the tuner to go up to channel 99 or thereabouts in cable position. I expected now the same, with the tuner just going even higher. Playing with the "connected to nothing" set downstairs in cable position still only allows channels 2 through 13. Same in both positions. Dunno. I'm waiting for my sons-in-law to help me load it into the car for the trip to the cabin - and the walleyes are waiting for our ceremonial 12:01 am casts off the end of the dock - grand daughter first, of course Walleye filets for breakfast... have a good weekend everyone. Take care. Ken |
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Toshiba RPTV 50H72 - blue screen only
You need an oscilloscope and isolation transformer to diagnose the set. You
also need to understand what HOT ground and Signal ground are and where they are located in the tv set for you scope ground (use the tuner shield). H-sync will be at horizontal sweep frequency pulse, 15kHz or 32Khz approximate, may be positive or negative going. V-sync will be at vertical sweep rate of usually 60Hz. The signal sync will be the combined vertical and horizontal sync with the video information removed. This is the one you really need to look at. Somewhere between the signal circuits and the system control. "bharat" wrote in message om... None of the sources I checked worked. The screen stays blue. No PIP either. Video is certainly (as far as I can tell) in blue screen mute mode (never heard of this before...but then I am not an expert on these matters!!!:-)). I haven't checked CC input as per David. I will check it tonight. RGB outputs on jungle IC are not what the manual says they should be (staying HIGH most of the time as David suggested). Last night, I checked the voltages on the sync inputs on micro. The H-Sync node on the micro is supposed to have 3.0V according to the manual and it was showing 2.5 (my kids came back before I could check it on oscilloscope...so had to give up). SCL1 and SDA1 (don't know what these signals are...if you can post something about their function, I will appreciate it) also are supposed to be 4.6V but were showing around 4.0V. All these measurements are DC. Rest of signals were showing expected (as per the schematic) voltages. Can a 0.5V drop on H-sync cause blue_screen mute? I will have to trace that one to see why that is low. Also, I will check all sync signals on oscilloscope to check for proper waveforms. Is micro the only circuit that will cause a blue-screen mute (BSM)? David had listed a lot of reasons for BSM but only micro as the controller for BSM. Another questions I have is how does the menu screen work if sync signals are messed up? I thought all screen functions will be needing sync signals and menu is certainly screen-based. Does this mean sync are OK but something else is causing BSM or are menu sync signals different from normal sync signals? Gotta run....I gave my final and kids are lining up to know their grades and I haven't graded the exams yet!! Why does my posting take a lot longer (at least it seems to me that way) than everyone else's posting? It seems David posted twice before mine even showed up! bharat |
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