LG 32LX1D will not turn on

[chicagodiyer]

Hi Folks, Ive gotten a used LG 32LX1D it will not turned on, only the little red light is on (not blinking, just on, from what I read its suppose to turn green when the tv is on).

I took out the back cover and plugged it in and a high pitch noise is coming out of the PSU, the noise sounds like this video but at about less than half the volume.

None of the capacitor in the PSU is bulged and i've tested the white fuse and it worked fine. I dont have an esr meter to test the capacitor to see if they are really good. this is the service manual of the tv. anyone has got any suggestion? PIctures of PSU

I dont have much background in electronics, but im good with a soldering iron, i've replaced quite a few bad caps in other tvs, even soldered quite a bit of smd led on some other project.

thanks

[momaka]

Re: LG 32LX1D will not turn on

Check all of the standby voltage outputs (if more than one). If not sure, post a picture of labels on the output connector. Also check to see if there are any bad capacitors on the main board. It will also be helpful if you posted some pictures here and not off-site (many members here prefer that for security and convenience reasons).

[MdPhoenix]

Re: LG 32LX1D will not turn on

I'll continue where this guy thoughtfully left off with no other comments.

I just obtained the same TV. Pretty wild inside. Has a PowerPC CPU and a SATA cable connecting the card reader. It has the potential for some awesome hacks.

Anyway, blinking red light, too. Gonna go through the service manual and check standby voltages as suggested. Anyone else have experience with this TV?

[MdPhoenix]

Re: LG 32LX1D will not turn on

Argh. Scribd requires membership to see the whole manual. I had no idea. Sigh.

[MdPhoenix]

Re: LG 32LX1D will not turn on

Checked all standby voltages. All testpoints on the flowchart failed. Not sure where to go from here. Start pulling caps and testing them? I'm clueless at this point.

[tom66]

Re: LG 32LX1D will not turn on

Argh. Scribd requires membership to see the whole manual. I had no idea. Sigh.

Just upload any manual to get free access. Welcome to upload any of the ones below in my signature...

[MdPhoenix]

Re: LG 32LX1D will not turn on

Wow. I had no idea. I already bought it, then downloaded a bunch of stuff I needed. Thank you though! Very nice of ya! Would uploading the manual here help you all to help me troubleshoot?

[tom66]

Re: LG 32LX1D will not turn on

Wow. I had no idea. I already bought it, then downloaded a bunch of stuff I needed. Thank you though! Very nice of ya! Would uploading the manual here help you all to help me troubleshoot?

Definitely. I'll upload it to my site as well.

[MdPhoenix]

Re: LG 32LX1D will not turn on

Here ya go! Thanks!

[MdPhoenix]

Re: LG 32LX1D will not turn on

Bump?

[manstoblame]

Re: LG 32LX1D will not turn on

Checked all standby voltages. All testpoints on the flowchart failed. Not sure where to go from here. Start pulling caps and testing them? I'm clueless at this point.

Dude I'm having problems with a Westinghouse LCDTV that wont power up but has a standby voltage of 3.3v and when turned on measures 4.3 at the PS_ON pin of its connector I'm not good at this either and really haven't gotten any response to my post but hey maybe it was because my image files sucked or what I think I think is I had the answer in the question. What I did was take out the N channel FET regulators and did an ohms test and have found two of the three I have on my SMPS are not measuring correctly. Now don't get it twisted I can't help you with how to go about all the processes to take to fix your set but you can find how to do via this forum source or Google I'm going to see if the bad FET voltage regulators solve my problems I've read they control the power breakdown and conversion. Hope there was something in this you can use and hey its always good to post Great images if you can good luck Oh I have no Idea what that noise could be unless its some resonance frequency due to open circuitry overload of current more than the device can handle and it vibrates creating harmonics and that's just smoke cause I really don't no what I'm talking about good luck though

BE CAREFULLLLLLLLLL
*Check the fuse if you get no power to the set I'd take it out to test

[MdPhoenix]

Re: LG 32LX1D will not turn on

Thanks bud. No noise here. I'll post pics of the board.

[MdPhoenix]

Re: LG 32LX1D will not turn on

Pics!!!!

[MdPhoenix]

Re: LG 32LX1D will not turn on

Any help?

[ben7]

Re: LG 32LX1D will not turn on

What is the standby voltage that you are getting?

When you try to power on the TV, test the voltage on the big filter capacitor. It will probably be somewhere around 400 volts if the PFC is working.

[momaka]

Re: LG 32LX1D will not turn on

First check ST5.0V (the 5V standby supply). Most likely it's there and fine, otherwise you wouldn't get any blinking codes or even be able to turn the TV on.

Next, disconnect power going to the inverter board and try turning the TV on again. I am assuming those red connectors on the top of the power supply board (can be seen in the first picture you uploaded) is what goes to the inverter. If the TV powers on and stays on, then the problem is on the inverter board. If not, check the voltage at those red connectors. Should be 24V or thereabouts. There is also a small white connector that has a pin labeled "24V_det". Not sure if this should be high or low (couldn't find the PSU schematic in the service manual), but when you try to power on the TV, it should change states.

If none of the voltages are coming on when you try to turn on the TV, disconnect all PSU connectors and try to turn it on manually. Connector CN802 has a pin labeled "PWR_CTRL1". Again, not sure if this should be high (5V) or low (0V) to turn on the PSU, but either grounding it or jumping it high (use a 100 Ohm resistor or thereabouts to be safe) should turn on the PSU and all of the voltages on the connectors should be present. Measure them all and make sure none of them are oscillating or going up and down. If they are, this could be a bad cap issue.

[MdPhoenix]

Re: LG 32LX1D will not turn on

Nice. Thanks all! I'll check these out tonight!

[MdPhoenix]

Re: LG 32LX1D will not turn on

The 5V standby is fluctuating between about 2.69vdc and 2.84 vdc with nothing connected to the PSU.
And I get nothing when I try to pull the PWR_CTRL1 high or low. Of course, I'm not sure where to get 5V to pull it high. I tried using the 2.8 from the standby. Silly? Probably. Wasn't sure what else to do.

I don't know if this helps, but I poked around a bit. Trying to see what voltages I could get. I get either 68 or 75 VDC on the high voltage side of PC102, PC103, and PC104. I'll keep checking things and try not to kill myself.

[momaka]

Re: LG 32LX1D will not turn on

The 5V standby is fluctuating between about 2.69vdc and 2.84 vdc with nothing connected to the PSU.

Okay, that right there indicates a problem with the standby. Before I jump to any conclusions, though, I ask that you double-check your multimeter by measuring the voltage of some AA or 9V batteries. If it it's not fluctuating, then the 5VSB of the power supply indeed has a problem.

And I get nothing when I try to pull the PWR_CTRL1 high or low.

Yes, when the 5V standby supply is not working, you won't be able to turn on the rest of the power supply either. The standby supply provides power to most (if not all) the logic chips on the power supply.

I don't know if this helps, but I poked around a bit. Trying to see what voltages I could get. I get either 68 or 75 VDC on the high voltage side of PC102, PC103, and PC104. I'll keep checking things and try not to kill myself.

Okay, let's take this step by step so you don't kill the PSU... or worse: start a fire or possibly shock yourself.

The first thing I'll have you do is check the resistance with your multimeter on the ST5.0V rail. You do this with the power completely disconnected from the power supply. When you do this, post what resistance you get. I assume you know how to measure resistance with your multimeter. If not, it's okay to ask.

Next, measure the voltage on that big SAMWHA capacitor on the primary side. Depending on PSU design, there should be either about 160V across it or 350 to 380V across it. Either way, the voltage should NOT oscillate across it.
But... BEWARE! This is the primary side and most components will be live - that means don't touch anything with your fingers. Also, because this is the primary side, you can't measure voltages with respect to normal ground. So to measure the voltage on that big SAMWHA capacitor, you will likely have to put the power supply on an insulated surface and have it flipped upside down so you can measure the voltage directly across its two leads. After you do this, post what voltages you get across that capacitor.

Most likely either the APFC is not working properly or the 5VSB start-up capacitor is bad. But we will see when you post results for the above items I asked.

[budm]

Re: LG 32LX1D will not turn on

Check or replace the 5VSTBY start up cap.