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Help Needed - Thomson 27LCDB03B not working

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Acrantophis:
OK you lost me in terminology; ??Tact switch?? Do you mean the On/Off push button on the side of the TV, if so this is known to be good, checked the switching continuity of it as one of the first probable causes.

I have been testing the PSU PCB as an individual item leaving the TV at home and working on the board at work during my lunch breaks, I do not know if this will give me the correct results or not but I don't appear to have any voltages at the various connectors CN701 to CN703 which supply the volatges to the Main PCB/Audio PCB/Tuner PCB/etc.

It could well be that there is an issue with the MOV as I have a low ohms reading across it which I think is wrong because typically these should have a high resistance reading at a low voltage and a low resistance at a high voltage, assuming my memory is still serving me correctly and I have correctly identified the device.

Anyway I will investigate further tomorrow (Friday) and provide an update.

Thanks again for all your guidance.

Acrantophis:
I might have discovered the cause, or I might not have. You never can tell with anything electronic until you actually replace it. Anyway I opted to lift pin 7 of U6301 to isolate it from the emitter of Q6302, upon measuring the voltage  at the point where pin 7 would solder to I started seeing +15Vdc so it could be U6301 is faulty or something it is supplying pulling the VCC low. Anyway, I'm off out for a beer tonight so will look into this more tomorrow.

astracat:
hi
that ic is a self starting oscillator ,sounds like you found problem suggest change it first
g/luck
astracat

Acrantophis:
 :08: Hi five Astracat! Together we've cracked it, appreciate the help. :c017:

Changing U6301 has resolved the problem, TV now back up and running. Just to confirm for anyone looking to fix the same power supply showing the same symptoms and they should subsequently stumble upon this post. The dc voltage to pin 7 of U6301 should be around 14V dc when working correctly. If you have the skills to lift the pin 7 re-measure the voltage at the PCB sniff point and see if it goes up to 15V which supports the IC failure as I found.

astracat:
hiya
glad its sorted well done
astracat

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