Jvc jlc32bc3000

[Nam3o]

Re: Jvc jlc32bc3000

no change

[tom66]

Re: Jvc jlc32bc3000

OK, so I suspect this device is faulty. (See attached.)

Can you get the part # on it? It is probably a PNP transistor but it could be a P-channel MOSFET.

[Nam3o]

Re: Jvc jlc32bc3000

Kia
431a
117

[tom66]

Re: Jvc jlc32bc3000

Oh, it's not either of those. I think I understand it. It's a voltage reference. It's regulating the 18V down to 12V, which is an odd way of doing things -- I'm not sure why they would do it that way. I need to trace out the circuit to understand why it's not working. I will be back.

[tom66]

Re: Jvc jlc32bc3000

OK, here is the voltage regulator part (see attached.) But I can't trace it fully yet as I don't know where R222 connects.

I remember seeing this circuit in a Samsung TV too. I think it is to reduce the standby power, by using a single transformer.

I need you to check which component this lead is part of (see attached.) I have a strong suspicion it is ground.

[Nam3o]

Re: Jvc jlc32bc3000

it connects to r285 then to q283.

[Nam3o]

Re: Jvc jlc32bc3000

this what I found

[tom66]

Re: Jvc jlc32bc3000

How difficult is it to make some tests on the power supply's rear side? I am thinking that the control signal is not reaching the TL431 or the TL431 is shorted out. I would need to know the voltage across R223.

[Nam3o]

Re: Jvc jlc32bc3000

R223 0v

[tom66]

Re: Jvc jlc32bc3000

OK, in which case, I am thinking it is a problem elsewhere on the PSU. (Probably in that large component area near the power connector.) It's not getting a signal from that part.

Is there a part # on it? I'd love to debug it more but it's proving a bit beyond me. If it's only about $20-30, it could be worth it.

[Nam3o]

Re: Jvc jlc32bc3000

I think this will help

[tom66]

Re: Jvc jlc32bc3000

Sorry, what?

[Nam3o]

Re: Jvc jlc32bc3000

Sorry, what?

No? did I fail to understand?

[tom66]

Re: Jvc jlc32bc3000

I was looking for the part number of the board, but I found it.
http://www.shopjimmy.com/vizio-0500-...t-inverter.htm

Never mind, it is very expensive! There is another thing you can do. If you don't mind the TV using a bit more power in standby, then the 12V can be forced on.

[Nam3o]

Re: Jvc jlc32bc3000

sounds good to me.

[tom66]

Re: Jvc jlc32bc3000

OK, see the attachment.

You need to cut the jumper link on the top between the two pads.

Then solder a 100 ohm resistor between the 18 ohm and the bottom most pad on the jumper link (nearest the KIA431.) 100 ohms is flexible. Anything up to a few 470 ohm down to 47 ohm should work. It's just to prevent damage in case of failure (the resistor should be the only casualty in the worst case.)

Very important: BEFORE you connect the main board double check the 12V output is giving 12V and not 18V! It should now be 12V all the time.

[Nam3o]

Re: Jvc jlc32bc3000

that did restore the 12v pins but it still wont turn on.

[tom66]

Re: Jvc jlc32bc3000

OK, that is very odd. I am confused, it should work. Was the TV hit by a surge? Any idea how it failed? Any different symptoms with 12V now?

[Nam3o]

Re: Jvc jlc32bc3000

no surge. the TV just slowly stopped coming on reliably. 12v seems ok

[tom66]

Re: Jvc jlc32bc3000

Does the TV do anything differently at all? Like, if it had no power LED before, does it have one? Can you turn it off once it is turned on?
You say it stopped turning on reliably -- does this mean it would turn on once in a while, but not always? Did it get slowly worse over time?