LCD Tv repair

[porsche4life]

Any of you guys have any ideas what to check out on this LCD tv I'm working on? When I got it(free) it had a bunch of bad caps on the power supply, and the board was toast. I replaced the power supply board with a used one off ebay, after attempting to repair the damage. Put the new board in and it still wouldn't fire up, not putting any power to the 24v output to the inverters, but is putting power to the main board. The company I bought the board from sent me another power board thinking that one was bad. This board is doing the same thing. I tested the capacitors on the inverters and they were toast so I replaced them. Still no 24v power out of the power supply.

What am I missing? Is the LCD panel itself bad? When I press the power button the standby light changes colors, but nothing else.

[Scuba Steve]

Are you applying a signal that has sound and does the backlight power on?

FWIW I repaired ours by swapping out the LCD driver board. When it was bad I was able to turn it on, change channels and hear whatever was playing but no video. Backlight turned on though, so that left only the LCD driver to replace. Under $20 repair and it's been good ever since.

[porsche4life]

no backlight, and the display isn't showing the usual dialog in the corner that tells you what input you are on. This is a vizio, identical to the tv we use, just bigger.

[Scuba Steve]

Hmm, sounds like a problem upstream from the LCD controller since normally that's separate from the backlight board(s). No sound would confirm it though. It does not sound like a problem with the actual LCD panel since you would still have backlighting.

To me it sounds like a problem with your main board. It probably sends a signal back to the power supply to power up once it gets a signal from the remote or you push a button to power on. You don't hear any relays clicking when you hit power?

[porsche4life]

When I hit the power button I hear a click and I hear the speakers make a small noise. Let me grab a cable.

[porsche4life]

Just cycled through the hdmi inputs and got audio output from my iPad on one. Still nothing on screen

[porsche4life]

Any other ideas guy?

[LeeH]

Originally Posted by porsche4life

Any other ideas guy?

Try putting a very bright flashlight up against the screen while you're in a very dark room. Hold the flashlight at various angles. Could be that the screen is on but the backlight is out. May help to press the "menu" button.

[porsche4life]

Doesn't seem to be when I try that.

[stomachmonkey]

Originally Posted by porsche4life

Doesn't seem to be when I try that.

Were you passing it a signal?

Backlight flashlight test requires something on screen.

[Scuba Steve]

Ok so we have established that you have sound. That's good. I suspect the LCD controller board has issues.

If you turn the tv on when the room is dark you may see glow from the backlighting, indicating those board(s) are operational.

[porsche4life]

Just checked again. Video is there, just no backlight. So... Bad inverters?

[onewhippedpuppy]

My Visio backlight died after my son shot it with a Nerf gun. A friend of mine took it to a repair place and they said that typically any repair on a budget tv is more expensive than buying a new one.

[Eric Coffey]

If you have replaced the inverter board and still no joy, then you might tear into the light array itself and check the CCFLs for arcing (should be obvious, at either end of one or more tubes/sockets).

[porsche4life]

I didnt replace the inverter board. Just the caps on them. I'll open it up and see if I can see anything wrong with the backlighting, if not I'll order some new inverter boards. The people I got it from said it popped, stopped working and let the smoke out. I assumed that was the result of the severely damaged power supply board with 6 blown caps. I guess those could have been the result of a bigger issue though. Over load from a bad cold cathode tube?

[Scuba Steve]

Originally Posted by porsche4life

Just checked again. Video is there, just no backlight. So... Bad inverters?

Backlight problems that I'm familiar with are due to bad boards that operate the backlighting. On smaller TVs there are one, about 47" and up there are two. Replacements are usually inexpensive and easy to swap out, so I would try throwing one at it first.

[porsche4life]

I found a place to buy the boards with a friendly return policy if they don't work.

Here's a few pics of the power supply board damage.

[porsche4life]

[1990C4S]

I will be posting for help next.

I have an RCA LED TV that is locked on one channel and the volume, channel, and remote functions do nothing....one channel, one volume setting ....that's it.