Home |
Search |
Today's Posts |
|
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. |
Reply |
|
LinkBack | Thread Tools | Display Modes |
#1
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
Some years ago, I built the flyback tester that was described in
Sams FAQs - the one with the simple two-transistor oscillator, connected by winding your own 10 turns onto the flyback core. The flyback is of course tested out-of-circuit. Over the years it has been quite accurate, but the results with one recent flyback are rather inconclusive, and I thought maybe you could give me some advice. I don't have the model # of the set handy, but it's a 36" Sony made in 1998. It came in with a blown HOT and switching regulator, so naturally the flyback was the first thing I suspected. Normally when a flyback is tested with this device, it will produce a decent-looking arc of about 1/2". The flyback in question, however, seems to produce a weak arc of less than 1/4", and it doesn't have the "sizzle" and thickness I normally see with this test. Given the size and high voltage requirements of the CRT, I expected a lot more from this flyback (if it's good, that is). Would I be right to suspect it as bad? I really don't want to replace the other components and leave the original flyback installed, because if it's bad, as you know, it will just take out the other components again (nice design, Sony). Any advice would be appreciated. |
#2
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
"packrat79" wrote in message ... Some years ago, I built the flyback tester that was described in Sams FAQs - the one with the simple two-transistor oscillator, connected by winding your own 10 turns onto the flyback core. The flyback is of course tested out-of-circuit. Over the years it has been quite accurate, but the results with one recent flyback are rather inconclusive, and I thought maybe you could give me some advice. I don't have the model # of the set handy, but it's a 36" Sony made in 1998. It came in with a blown HOT and switching regulator, so naturally the flyback was the first thing I suspected. Normally when a flyback is tested with this device, it will produce a decent-looking arc of about 1/2". The flyback in question, however, seems to produce a weak arc of less than 1/4", and it doesn't have the "sizzle" and thickness I normally see with this test. Given the size and high voltage requirements of the CRT, I expected a lot more from this flyback (if it's good, that is). Would I be right to suspect it as bad? I really don't want to replace the other components and leave the original flyback installed, because if it's bad, as you know, it will just take out the other components again (nice design, Sony). Any advice would be appreciated. How much is a new flyback? A while back I replaced one on a 32" Sony which was arcing internally, it was surprisingly inexpensive and fixed the problem. |
#3
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
"James Sweet" wrote in
news:iADvj.13$A93.12@trndny08: "packrat79" wrote in message .. . Some years ago, I built the flyback tester that was described in Sams FAQs - the one with the simple two-transistor oscillator, connected by winding your own 10 turns onto the flyback core. The flyback is of course tested out-of-circuit. Over the years it has been quite accurate, but the results with one recent flyback are rather inconclusive, and I thought maybe you could give me some advice. I don't have the model # of the set handy, but it's a 36" Sony made in 1998. It came in with a blown HOT and switching regulator, so naturally the flyback was the first thing I suspected. Normally when a flyback is tested with this device, it will produce a decent-looking arc of about 1/2". The flyback in question, however, seems to produce a weak arc of less than 1/4", and it doesn't have the "sizzle" and thickness I normally see with this test. Given the size and high voltage requirements of the CRT, I expected a lot more from this flyback (if it's good, that is). Would I be right to suspect it as bad? I really don't want to replace the other components and leave the original flyback installed, because if it's bad, as you know, it will just take out the other components again (nice design, Sony). Any advice would be appreciated. How much is a new flyback? A while back I replaced one on a 32" Sony which was arcing internally, it was surprisingly inexpensive and fixed the problem. I recently put a new flyback in a 12" TV,it cost less than $20 from Acme Enterprises. My old FB smoked. -- Jim Yanik jyanik at kua.net |
#4
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
On Feb 22, 1:34 pm, Jim Yanik wrote:
"James Sweet" wrote innews:iADvj.13$A93.12@trndny08: "packrat79" wrote in message .. . Some years ago, I built the flyback tester that was described in Sams FAQs - the one with the simple two-transistor oscillator, connected by winding your own 10 turns onto the flyback core. The flyback is of course tested out-of-circuit. Over the years it has been quite accurate, but the results with one recent flyback are rather inconclusive, and I thought maybe you could give me some advice. I don't have the model # of the set handy, but it's a 36" Sony made in 1998. It came in with a blown HOT and switching regulator, so naturally the flyback was the first thing I suspected. Normally when a flyback is tested with this device, it will produce a decent-looking arc of about 1/2". The flyback in question, however, seems to produce a weak arc of less than 1/4", and it doesn't have the "sizzle" and thickness I normally see with this test. Given the size and high voltage requirements of the CRT, I expected a lot more from this flyback (if it's good, that is). Would I be right to suspect it as bad? I really don't want to replace the other components and leave the original flyback installed, because if it's bad, as you know, it will just take out the other components again (nice design, Sony). Any advice would be appreciated. How much is a new flyback? A while back I replaced one on a 32" Sony which was arcing internally, it was surprisingly inexpensive and fixed the problem. I recently put a new flyback in a 12" TV,it cost less than $20 from Acme Enterprises. My old FB smoked. -- Jim Yanik jyanik at kua.net So chances are it probably is bad huh? That's what I figured. However, Sony has discontinued this part, so a generic replacement will have to do (I could only find one supplier, with one left in stock). I didn't think Sony discontinued parts so soon, but I guess that's the trend these days. |
#5
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
So chances are it probably is bad huh? That's what I figured. However, Sony has discontinued this part, so a generic replacement will have to do (I could only find one supplier, with one left in stock). I didn't think Sony discontinued parts so soon, but I guess that's the trend these days. Hard to say for sure, but if it isn't super expensive it might be worthwhile to just replace it and see what happens. Flybacks can be difficult to test, there's too many characteristics that are critical in some sets. I have a flyback ring tester which works pretty well but even that isn't 100%. |
#6
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
"James Sweet" writes:
So chances are it probably is bad huh? That's what I figured. However, Sony has discontinued this part, so a generic replacement will have to do (I could only find one supplier, with one left in stock). I didn't think Sony discontinued parts so soon, but I guess that's the trend these days. Hard to say for sure, but if it isn't super expensive it might be worthwhile to just replace it and see what happens. Flybacks can be difficult to test, there's too many characteristics that are critical in some sets. I have a flyback ring tester which works pretty well but even that isn't 100%. I agree. If the self oscillating circuit works as well as it did, a ring test probably won't be any more definitive without a side-by-side compsrison. You may have to try a new one. You might compare the DC current through the oscillator with the suspect flyback, and with a known good one. If it's really significantly higher, then that would be one more piece of evidence suggesting a bad flyback. --- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/ Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. |
#7
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
On Feb 22, 6:14*pm, Sam Goldwasser wrote:
"James Sweet" writes: So chances are it probably is bad huh? That's what I figured. However, Sony has discontinued this part, so a generic replacement will have to do (I could only find one supplier, with one left in stock). I didn't think Sony discontinued parts so soon, but I guess that's the trend these days. Hard to say for sure, but if it isn't super expensive it might be worthwhile to just replace it and see what happens. Flybacks can be difficult to test, there's too many characteristics that are critical in some sets. I have a flyback ring tester which works pretty well but even that isn't 100%. I agree. *If the self oscillating circuit works as well as it did, a ring test probably won't be any more definitive without a side-by-side compsrison. *You may have to try a new one. You might compare the DC current through the oscillator with the suspect flyback, and with a known good one. *If it's really significantly higher, then that would be one more piece of evidence suggesting a bad flyback. --- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ *Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm * * * * | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. *Or, you can contact me via the Feedback Form in the FAQs. CAn you give a URL for the tester you mentioned. I didn't see one on Sam Goldwasser's repair FAQ site. H. R. (Bob) Hofmann |
#9
Posted to sci.electronics.repair
|
|||
|
|||
Validity of Flyback Test?
On Feb 24, 12:42*am, "James Sweet" wrote:
"hr(bob) " wrote in message ... On Feb 22, 6:14 pm, Sam Goldwasser wrote: "James Sweet" writes: So chances are it probably is bad huh? That's what I figured. However, Sony has discontinued this part, so a generic replacement will have to do (I could only find one supplier, with one left in stock). I didn't think Sony discontinued parts so soon, but I guess that's the trend these days. Hard to say for sure, but if it isn't super expensive it might be worthwhile to just replace it and see what happens. Flybacks can be difficult to test, there's too many characteristics that are critical in some sets. I have a flyback ring tester which works pretty well but even that isn't 100%. I agree. If the self oscillating circuit works as well as it did, a ring test probably won't be any more definitive without a side-by-side compsrison. You may have to try a new one. You might compare the DC current through the oscillator with the suspect flyback, and with a known good one. If it's really significantly higher, then that would be one more piece of evidence suggesting a bad flyback. --- sam | Sci.Electronics.Repair FAQ:http://www.repairfaq.org/ Repair | Main Table of Contents:http://www.repairfaq.org/REPAIR/ +Lasers | Sam's Laser FAQ:http://www.repairfaq.org/sam/lasersam.htm | Mirror Sites:http://www.repairfaq.org/REPAIR/F_mirror.html Important: Anything sent to the email address in the message header above is ignored unless my full name AND either lasers or electronics is included in the subject line. Or, you can contact me via the Feedback Form in the FAQs. CAn you give a URL for the tester you mentioned. I didn't see one on Sam Goldwasser's repair FAQ site. H. R. (Bob) Hofmann This is the one I have: http://members.ozemail.com.au/~bobpar/fbt.htm- Hide quoted text - - Show quoted text - Thanx! |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Flyback.pdf - Flyback.pdf | Electronic Schematics | |||
Survey Validity? | Home Ownership | |||
Need Flyback TX | Electronics Repair | |||
flyback | Electronics Repair | |||
Mac Plus flyback? | Electronics Repair |