This set came into my possession stuck in standby, would switch on for a second or so but no picture or sound, then switch off again.
After doing a bit of research on the web I discovered that I might have some blown transistors right before the inverter transformers which there are four of on the board (see attached pic with two transformers and 4 of the transistors removed for testing) There are two of these 2SD965 transistors per transformer.
Long story short, I pulled and checked two of the transformers for short circuit, they both tested the same (0.6 ohms on primarys and 370 ohms on secondaries) so I assume they are fine.
I refitted the transformers and removed the transistors Q7 thru Q14 and tried to power up, the set came on and stayed on - I had audio (obviously no video)
Fitted the new transistors and powered it up again, thought I had cured it, it came out of standby for about 5-6 seconds then there was like a crack noise that sounded like a component blowing around the top of the tv somewhere (or perhaps it was my new transistors, difficult to say)
So, now im back to square one.. Am I right in thinking that this must be a CCFL problem as there is nothing wrong with the transformers? Would I do damage if I try replacing the transistors again and leave the HT leads off the tubes to eliminate them? (can the inverter cope with no load?)
Cheers,
Jim
ps again, please excuse the quality of photo - I really need to get better lighting and camera for the workshop
After doing a bit of research on the web I discovered that I might have some blown transistors right before the inverter transformers which there are four of on the board (see attached pic with two transformers and 4 of the transistors removed for testing) There are two of these 2SD965 transistors per transformer.
Long story short, I pulled and checked two of the transformers for short circuit, they both tested the same (0.6 ohms on primarys and 370 ohms on secondaries) so I assume they are fine.
I refitted the transformers and removed the transistors Q7 thru Q14 and tried to power up, the set came on and stayed on - I had audio (obviously no video)
Fitted the new transistors and powered it up again, thought I had cured it, it came out of standby for about 5-6 seconds then there was like a crack noise that sounded like a component blowing around the top of the tv somewhere (or perhaps it was my new transistors, difficult to say)
So, now im back to square one.. Am I right in thinking that this must be a CCFL problem as there is nothing wrong with the transformers? Would I do damage if I try replacing the transistors again and leave the HT leads off the tubes to eliminate them? (can the inverter cope with no load?)
Cheers,
Jim
ps again, please excuse the quality of photo - I really need to get better lighting and camera for the workshop
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