Toshiba 32hl66 32" LCD TV, won't light up

[Mrx3750]

This is a TV that I bought cheap several months ago off of Craigslist, thinking it would be an easy fix. I was told that the siene board was faulty and that if I replaced that, the TV would work. Got a replacement board, put it in, and no joy.

I'm going to take one more crack at fixing this TV. I did a quick test connecting my multimeter to the positive lead of the biggest capacitor in the PSU, and negative lead to the chassis. Plugging it in, I got a few brief voltage spikes, but nothing else.

The TV will do its booting up sequence (LED flashes I think three times. I know it's not blinking an error code.) and it will appear to turn on, but there's no picture.

I have checked every capacitor on the power supply, and replaced a few marginal ones on the mainboard. I'm at a loss as to what to look for now.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Do you see a change in output voltages on the power connector after you press the button, or after the light blinks?

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Power connector? Which one?

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Sorry, connector on the power supply going to other boards.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Okay, there's two power connectors. Which one (or both?) should I look at, and which pins should I test? If need be I'll grab an underside shot of the board.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Do both. If there are any labels on either end, refer to those in your post.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Okay, doing the ribbon connector is too tricky... I fear the probe slipping and shorting something that won't bear being shorted. However I tested the pins at the white plastic connector. Starting from the white wire, negative lead on chassis ground, I get 24 volts DC on I think four of those wires when the TV is turned on.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

This indicates your power supply is working. Can you trace the 24V connector? I expect it goes under the frame to an "inverter" board which lights up the screen. The connector may split off and one end may go to the main board.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Yes, that cable goes to the inverter board.

This is what I was afraid of. I narrowed it down to the power supply or the inverter board before I gave up on it. The capacitors on the inverter board are good.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

What I'm asking about is if you can locate the connector with the control signals on it -- one may contain the "BL ON" signal. If the BL ON signal is turning on, then the inverter is at fault as it is not lighting up, but if it is not turning on the main board is likely the culprit.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Lets see here, that cable from the power supply, the one I tested, all the wires go to the inverter board. However here's something interesting. There are two connectors on that board. See attached.

So, I know that 24 VDC is going to that board. I wonder what that other connector is for.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

The other connector is not used. Some of the wires from that connector will go to the power supply... and the others will go somewhere else. Where do they go?

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Oh, wait you're right. It splits off and goes to a board conveniently located under the tuner

So I should check that cable for voltages then?

Oh, and is it okay to remove the tuner board for testing this?

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Any way you can test the voltages on this cable with it installed? Maybe you will need to insert wires into each of the connection pins to get a solid connection. It's clear these older Toshibas were designed by ex-NASA engineers going by how much they stuffed into such a small chassis.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

All right, that was a pain in the ass, but I'm getting 5 volts off the white wire on that connector under the tuner, and on another wire I got around 3.2 volts.

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

In which case, the fault is with the inverter or tubes in the panel -- likely the inverter.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Yep, just as I feared.

Okay, so can I possibly fix the inverter board? or do I need to find another one? If so, where do I find another one?

[tom66]

Re: Toshiba 32hl66 32" LCD TV, won't light up

You can remove it and do some tests, quite likely you can fix it but they are also often available as replacement parts.

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Seeing as I'm not seeing a replacement in stock on Google or eBay, what tests can I do on it?

[Mrx3750]

Re: Toshiba 32hl66 32" LCD TV, won't light up

Actually, found it by part number. That's great, but I've already sunk about $70 into this TV. I want to be certain it's the inverter board.