Re: RCA 42LA45RQ with no HV to the backlight

OK, I have more time today so I took some voltage measurements on the board. The picture gives some more detail but basically the 5 and 12 volts are where they should be. the RED square has a pin-out of the contacts above.
The adjust is about 1.8 volts. I don't know what that should be but it sounds reasonable. The ON/OFF though is only 0.35 volts which to me means off. How do I trace that back to what is turning that on and off? That seems to be my problem. Also the chip is an LM324 pulse width modulator. I am assuming that is...

Re: RCA 42LA45RQ with no HV to the backlight

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Re: RCA 42LA45RQ with no HV to the backlight

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Re: RCA 42LA45RQ with no HV to the backlight

Budm,

thanks for the guidance and effort to help. I have several pictures of the board with close-ups of the labels on the board and TV frame. I hope this is good enough. I took it with a 6 M pixel Pro camera and I am sure the forum will shrink them. I hope the resolution stays readable.

Well, it barfed on sending all so I will break them up into three posts. Almost forgot the back of the board!!

Thanks for any advice,

Russell...

Greetings All,


I have a back light issue. I have tried to detect high voltage with a high voltage probe which is giving me a zero reading. I have tried a second board that was supposed to be good and I get the same results. I have sound and the receiver is working. I am wondering if there is a separate trigger signal for the high voltage separate from the trigger for the receiver processor board. Anyone know? I assume that the larger chip on the back side of the board is some kind of modulator to get the HV transformers going. Is ther a way to check if it is woking?
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Re: RCA 42LA45RQ no backlights, bodged cap replacement on PSU

Greetings All,

I have the same RCA 42LA45RQ but my inverter board is some what different. I also have a back light issue. I have tried to detect high voltage with a high voltage probe which is giving me a zero reading. I have tried a second board that was supposed to be good and I get the same results. I have sound and the receiver is working. I am wondering if there is a separate trigger signal for the high voltage separate from the receiver processor board. Anyone know?

Here is a slightly...