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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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#1
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CRT vertical deflection -- bad solder joints?
On Monday, March 28, 2011 4:15:45 AM UTC-7, Mike Tomlinson wrote:
In article s.com, Sean Hamilton writes Is it likely that bad solder joints would cause vertical foldover in a mid-90s CRT television? Yes, but it's more likely to be a bad cap. Visual inspection is not enough. You need an ESR meter. Maybe not; the ESR issues crop up mainly in high-performance low voltage power supplies (like computers); the vertical sweep circuit doesn't need a low-ESR capacitor. It will take (and work well with) just about any capacitor with adequate voltage rating and capacity. The capacitor is inexpensive; just replace it with a new one, don't bother with testing the old unit. |
#2
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CRT vertical deflection -- bad solder joints?
"whit3rd" wrote in message ... On Monday, March 28, 2011 4:15:45 AM UTC-7, Mike Tomlinson wrote: In article s.com, Sean Hamilton writes Is it likely that bad solder joints would cause vertical foldover in a mid-90s CRT television? Yes, but it's more likely to be a bad cap. Visual inspection is not enough. You need an ESR meter. Maybe not; the ESR issues crop up mainly in high-performance low voltage power supplies (like computers); the vertical sweep circuit doesn't need a low-ESR capacitor. It will take (and work well with) just about any capacitor with adequate voltage rating and capacity. The capacitor is inexpensive; just replace it with a new one, don't bother with testing the old unit. I think you are missing the point of what he was saying regarding ESR. This parameter is a valid test of the 'goodness' of any electrolytic capacitor, regardless of its ESR pedigree. Even 'normal' electrolytics have a relatively low ESR when they are properly functional. As they fail, that figure will increase, and that is readily spotted with an ESR meter. As to the OP's actual problem, whilst bad joints in vertical output stages in CRT televisions were common, this more often lead to initially intermittent, and finally permanent frame collapse, than geometry problems like foldover, which the OP said was the problem he had. My money would be 100% on it being a bad cap, or possibly the feed resistor to the output IC having gone high. This was also a relatively common problem on many chassis, and could cause a severe foldover, usually at the bottom of the screen where the deflection drive current needed to be at its highest. Arfa |
#3
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CRT vertical deflection -- bad solder joints?
In article , Arfa Daily
writes I think you are missing the point of what he was saying regarding ESR. I think so too ) My money would be 100% on it being a bad cap +1 -- Mike Tomlinson |
#4
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CRT vertical deflection -- bad solder joints?
Hello? Instead of fussing over it, why not replace all the electrolytics "in
the vicinity" while the bad-looking solder joints are being re-done? This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. |
#5
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CRT vertical deflection -- bad solder joints?
In article , William Sommerwerck
writes This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. If you're fixing stuff regularly, particularly many of the same item, it's worth diagnosing the problem so that in future you can say, "oh, that model, that fault, it's C35", and replace that - saving time and the cost of replacing components unnecessarily. -- Mike Tomlinson |
#6
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CRT vertical deflection -- bad solder joints?
"William Sommerwerck" wrote in message ... Hello? Instead of fussing over it, why not replace all the electrolytics "in the vicinity" while the bad-looking solder joints are being re-done? This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. Arfa |
#7
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CRT vertical deflection -- bad solder joints?
"Mike Tomlinson" wrote in message ... In article , William Sommerwerck writes This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. If you're fixing stuff regularly, particularly many of the same item, it's worth diagnosing the problem so that in future you can say, "oh, that model, that fault, it's C35", and replace that - saving time and the cost of replacing components unnecessarily. -- Mike Tomlinson Seconded ... Arfa |
#8
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CRT vertical deflection -- bad solder joints?
This is a common problem in servicing. As an EE, I want to know
exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. I don't understand how shotgunning can /create/ problems, as long as the replaced components are correct replacements. Unless you mean the customer might get upset. As an experienced service technician, you know that the cause of a given problem is not always obvious, even after extensive troubleshooting. The customer is paying for your time, often more than what the parts cost. Why burn up the customer's money when replacing a half-dozen parts is likely to fix the thing? |
#9
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CRT vertical deflection -- bad solder joints?
"Arfa Daily" wrote in message
... "William Sommerwerck" wrote in message ... Hello? Instead of fussing over it, why not replace all the electrolytics "in the vicinity" while the bad-looking solder joints are being re-done? This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. Arfa I have seen sets (notably Toshiba and Mitsubishi) where shotgunning was advisable in addition to replacing whichever single cap might have been causing your issue. Mark Z. |
#10
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CRT vertical deflection -- bad solder joints?
On Wed, 30 Mar 2011 07:38:43 -0500, Mark Zacharias wrote:
"Arfa Daily" wrote in message ... "William Sommerwerck" wrote in message ... Hello? Instead of fussing over it, why not replace all the electrolytics "in the vicinity" while the bad-looking solder joints are being re-done? This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. Arfa I have seen sets (notably Toshiba and Mitsubishi) where shotgunning was advisable in addition to replacing whichever single cap might have been causing your issue. Mark Z. We used to call some of the factory repair 'kits' for certain Panasonic sets "shotgun packs" because of the amount of components included. Some of those even included parts not on the board that were to be added on the solder side. -- Live Fast Die Young, Leave A Pretty Corpse |
#11
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CRT vertical deflection -- bad solder joints?
In article , William Sommerwerck
writes But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? -- Mike Tomlinson |
#12
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CRT vertical deflection -- bad solder joints?
On Wed, 30 Mar 2011 16:31:15 +0100, Mike Tomlinson wrote:
In article , William Sommerwerck writes But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? Isn't that an unfair comparison? -- Live Fast Die Young, Leave A Pretty Corpse |
#13
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CRT vertical deflection -- bad solder joints?
But I learned a long time ago that it's more important to simply
get the damned thing fixed. If that means shotgunning likely components, so be it. Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? Yes, if an initial /conscientious/ troubleshoot didn't reveal the problem. I'd rather pay for parts than time. Of course, you can't draw an exact parallel between cars and electronic equipment. It's easier to "see" what is wrong with mechanical devices, but car parts tend to be more-expensive than electronic parts. |
#14
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CRT vertical deflection -- bad solder joints?
In article ,
Mike Tomlinson wrote: Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? It's commonly done. Had a girlfriend a few years back who took her car in because it was overheating. They called with the estimate (of many hundreds of dollars,) saying they had determined that it needed a new radiator, new water pump, new thermostat, and new hoses. I went down there and asked them how they had determined the radiator fault, and they claimed to have pressure tested it. A 15 second look under the hood confirmed my suspicion that they had not. I took the car and replaced the thermostat - $12 and 1/2 hour - and it served her for several more years. The shop in question is consistently voted winner of the annual "Reader's Poll" in our local rag. Oddly, I don't think they operate that way solely to cheat the customer financially. I think they're more driven by not wanting any return complaints. That's why the "Readers" like them -- "they fixed it right the first time!!" I drove around town for the next 3 months with a giant sign in my back window: "Richard's Auto: As Crooked As the Day is Long." I got a lot of stories from people who saw the sign, about their own bad experiences there. |
#15
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CRT vertical deflection -- bad solder joints?
Would you be happy for a car mechanic to shotgun a fault on your
car, with you paying for his time and all the parts he is unnecessarily fitting? It's commonly done. Had a girlfriend a few years back who took her car in because it was overheating. They called with the estimate (of many hundreds of dollars), saying they had determined that it needed a new radiator, new water pump, new thermostat, and new hoses. I went down there and asked them how they had determined the radiator fault, and they claimed to have pressure-tested it. A 15-second look under the hood confirmed my suspicion that they had not. I took the car and replaced the thermostat -- $12 and 1/2 hour -- and it served her for several more years. The shop in question is consistently voted winner of the annual "Reader's Poll" in our local rag. Oddly, I don't think they operate that way solely to cheat the customer financially. I think they're more driven by not wanting any return complaints. That's why the "Readers" like them -- "they fixed it right the first time!!" There's also the possibility that a comprehensive makes it possible to offer a "lifetime" warranty on the repair. I drove around town for the next 3 months with a giant sign in my back window: "Richard's Auto: As Crooked As the Day is Long." I got a lot of stories from people who saw the sign, about their own bad experiences there. It goes without saying that if a service shop claims that lots of things need fixing, it's probably not telling the truth. Thirty years ago I worked part-time -- at $6/hour -- for Chestnut Hill Audio in Philadelphia. The owner said to me "You're not as fast as the other people I use -- but nothing you repair comes back." I had a holy horror of callbacks. It costs the business money, and it makes the business and the service tech look bad. By the way, I never shotgunned anything I repaired there, because nothing seemed to need it. |
#16
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CRT vertical deflection -- bad solder joints?
"William Sommerwerck" wrote in message ... This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. I don't understand how shotgunning can /create/ problems, as long as the replaced components are correct replacements. Unless you mean the customer might get upset. As an experienced service technician, you know that the cause of a given problem is not always obvious, even after extensive troubleshooting. The customer is paying for your time, often more than what the parts cost. Why burn up the customer's money when replacing a half-dozen parts is likely to fix the thing? Every component that is replaced, increases the potential margin for error by the person replacing it. I have had many items cross my bench over the years, which have been 'elsewhere' first, and have seen wrong values fitted, caps in backwards, diodes in backwards, damaged print and so on, amongst the many components that have have obviously been shotgunned, as evidenced by the flux all over their joints. I have also seen unsuitable substitutes fitted, where technicians have had insufficient understanding of the requirements of a circuit's design, and have just put in 'what came to hand' in order to complete their shotgun. Very occasionally, it is necessary to replace a block of components, when a fault is particularly obscure, but I would never recommend it as an acceptable procedure to anyone who wasn't hugely experienced in the field of service work, and particularly in the case of a simple problem such as the OP has with his TV's field scanning, and which would be easily diagnosed with the use of appropriate test equipment. Arfa |
#17
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CRT vertical deflection -- bad solder joints?
"Mark Zacharias" wrote in message eb.com... "Arfa Daily" wrote in message ... "William Sommerwerck" wrote in message ... Hello? Instead of fussing over it, why not replace all the electrolytics "in the vicinity" while the bad-looking solder joints are being re-done? This is a common problem in servicing. As an EE, I want to know exactly why something isn't working correctly. But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Shotgunning is, IMHO, very bad practice, and often leads to the creation of more problems than it fixes. I am actually quite surprised that you would advocate doing this, William. Arfa I have seen sets (notably Toshiba and Mitsubishi) where shotgunning was advisable in addition to replacing whichever single cap might have been causing your issue. Mark Z. Occasionally, this is true, but only - for me at least - if the manufacturer has recommended a block of components to be replaced, on the grounds that some or all of the additional ones, may have been unacceptably stressed or damaged, by the primary failure. In these cases, the manufacturer or his spares agent usually supplies 'service kits' of all the necessary components. Often the case with switch mode power supplies. As in, for instance http://www.ohmsupplies.co.uk/ Arfa |
#18
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CRT vertical deflection -- bad solder joints?
"William Sommerwerck" wrote in message ... But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? Yes, if an initial /conscientious/ troubleshoot didn't reveal the problem. I'd rather pay for parts than time. Of course, you can't draw an exact parallel between cars and electronic equipment. It's easier to "see" what is wrong with mechanical devices, but car parts tend to be more-expensive than electronic parts. I'm not at all sure you would say that if one of the incorrectly fitted parts was the EMU, for example. This, and many of the expensive sensors on engines nowadays, are usually 'bonded' parts, and once the box has been opened, the supplier will not accept it back, which leaves you paying for it, when it was not required. A while ago, I had just this problem with my local garage, who replaced a cartload of parts and sensors on my engine, for an idle problem that ultimately turned out to be due to a split in the PCV hose. I argued with them long and hard about having to pay for parts that had been shotgunned due to the fact that the guy doing the job had not correctly diagnosed the problem. I eventually had to settle for a reduced labour bill to offset the unnecessary parts cost, which they were determined were staying on the engine, and that I was going to be paying for (at retail price, just to make it worse) Arfa |
#19
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CRT vertical deflection -- bad solder joints?
"William Sommerwerck" wrote in message ... Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? It's commonly done. Had a girlfriend a few years back who took her car in because it was overheating. They called with the estimate (of many hundreds of dollars), saying they had determined that it needed a new radiator, new water pump, new thermostat, and new hoses. I went down there and asked them how they had determined the radiator fault, and they claimed to have pressure-tested it. A 15-second look under the hood confirmed my suspicion that they had not. I took the car and replaced the thermostat -- $12 and 1/2 hour -- and it served her for several more years. The shop in question is consistently voted winner of the annual "Reader's Poll" in our local rag. Oddly, I don't think they operate that way solely to cheat the customer financially. I think they're more driven by not wanting any return complaints. That's why the "Readers" like them -- "they fixed it right the first time!!" There's also the possibility that a comprehensive makes it possible to offer a "lifetime" warranty on the repair. I drove around town for the next 3 months with a giant sign in my back window: "Richard's Auto: As Crooked As the Day is Long." I got a lot of stories from people who saw the sign, about their own bad experiences there. It goes without saying that if a service shop claims that lots of things need fixing, it's probably not telling the truth. Thirty years ago I worked part-time -- at $6/hour -- for Chestnut Hill Audio in Philadelphia. The owner said to me "You're not as fast as the other people I use -- but nothing you repair comes back." I had a holy horror of callbacks. It costs the business money, and it makes the business and the service tech look bad. By the way, I never shotgunned anything I repaired there, because nothing seemed to need it. Which is precisely what I'm saying. Yes, there are some items - notably switch mode power supplies - where it is often prudent, or even recommended by the manufacturer, to replace a whole raft of parts, but for most general repairs, the cause of the problem should be correctly diagnosed, and the (usually) one faulty component replaced. Arfa |
#20
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CRT vertical deflection -- bad solder joints?
Every component that is replaced, increases the potential margin for error
by the person replacing it. I have had many items cross my bench over the years, which have been 'elsewhere' first, and have seen wrong values fitted, caps in backwards, diodes in backwards, damaged print and so on, amongst the many components that have have obviously been shotgunned, as evidenced by the flux all over their joints. I have also seen unsuitable substitutes fitted, where technicians have had insufficient understanding of the requirements of a circuit's design, and have just put in 'what came to hand' in order to complete their shotgun. Yes, but you and I don't make such mistakes. |
#21
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CRT vertical deflection -- bad solder joints?
In article , Meat Plow
writes Isn't that an unfair comparison? Tell me how. Not being argumentative, I'd be genuinely interested to hear why you think it's unfair. -- Mike Tomlinson |
#22
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CRT vertical deflection -- bad solder joints?
"Mike Tomlinson" wrote in message
... In article , William Sommerwerck writes But I learned a long time ago that it's more important to simply get the damned thing fixed. If that means shotgunning likely components, so be it. Would you be happy for a car mechanic to shotgun a fault on your car, with you paying for his time and all the parts he is unnecessarily fitting? -- Mike Tomlinson If the parts are cheap with little or no additional labor, and done to prevent a repeat failure in the near time frame, as is often the case with TV's, then yes, I would be happy, and so are my customers. Mark Z. |
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