LG 42LC2D Power Supply Issue

[slidr]

Does anyone have the schematic for PSU: 6709900017A (YP4201 06.02.15 Rev. 1.3)?

I replaced 4 10V 2200MF capacitors, and now when plugged in, it clicks once while illuminating the green LED on the front of the TV, then immediately clicking again, turning the LED off. I then have to leave the TV unplugged for at least 5-10 mins before I plug it in, in order for it to do it again. If I plug it back in right away, nothing happens...no green LED, no click.

While plugged in, I get the following readings...

At P201

• AC pin = 2.25v
• POW pin = .01v
• 5V pin = 5v
• ERR pin = 4.98v
• 5V pin = 5v
• DIM pin = 4.98v
• 6V pin = .01v
• 3.4 O/F pin = 0.14v

At P202

• 19V pin = 19.28v (and drops at rate of 0.01v/sec)
• 19V pin = 19.24v (and drops at rate of 0.01v/sec)
• 6V pin = 0v
• 3.4V pin = 0v
• 12V pin = .37v (and drops at a rate of 0.02v/sec)

I'm assuming that I'm not a candidate for the AC Detect optocoupler fix since I see the 5v?

Thanks.

[joeytino]

Re: LG 42LC2D Power Supply Issue

I saw your post and wondered if you ever found a schematic. I have the same TV, but in my case I have nothing on the 3.4 volt outputs. It seems these boards have a pretty high failure rate and you would think there would be more info on them out there.

Best regards.

[saddle_au]

Re: LG 42LC2D Power Supply Issue

I have had the same problem in the 32 inch version and it turned out to be the cable between the power supply and the motherboard. The connections were bad/intermittent.

[dick_barton]

Re: LG 42LC2D Power Supply Issue

I saw your post and wondered if you ever found a schematic. I have the same TV, but in my case I have nothing on the 3.4 volt outputs. It seems these boards have a pretty high failure rate and you would think there would be more info on them out there.

Best regards.

Service manual may help you.
http://www.umlib.com/brand/LG/catego...ocument/683229

[joeytino]

Re: LG 42LC2D Power Supply Issue

Service manual may help you.
http://www.umlib.com/brand/LG/catego...ocument/683229

Thanks for the link, but...

You would think that would be the go to place but LG frustratingly left the schematic for the power supply out of the service manual and simply tells you to replace it. Understandable for in the field service, but when you are able to fix it, that is not much help.

[NJ1Q]

Re: LG 42LC2D Power Supply Issue

Hi all,

I had a similar issue. A number of the p/s caps were "pregnant." I replaced them with higher voltage values, and the TV has worked fine for years. But, it started acting up again. A couple of clicks after power up, and then nothing. None of the caps look bad.

Now, I do not have the STBY 5 volts present. There was mention of the AC optocoupler issue and the (lack) of 5 volts. I cannot find that issue mentioned anywhere else. Nor can I find a schematic for the p/s.

Could someone enlighten me on the issue? I see there are at least four (4) optocouplers. But, I cannot make out the part numbers very well.

Thanks!


Rather frsutrating!

[budm]

Re: LG 42LC2D Power Supply Issue

Lets see good clear straight shot pictures of the whole top and bottom side of YOUR power supply board.

[NJ1Q]

Re: LG 42LC2D Power Supply Issue

Sorry about that. Same P/S, but for a LG 42LB1DRA.

No 5 V with AC power. But, when first applying AC power, there is 5 V on P201 but for just a split second. Nothing afterwards.

Thanks.

[budm]

Re: LG 42LC2D Power Supply Issue

So do you get the Voltages if you power the board by itself without other boards connected?

[NJ1Q]

Re: LG 42LC2D Power Supply Issue

That I didn't as yet try. But I can do that.

[NJ1Q]

Re: LG 42LC2D Power Supply Issue

I disconnected all the connections from the power supply board. Oddly enough, the only voltage present when AC power is supplied is the 5 V. There are no other voltages present.

[BMARo]

Re: LG 42LC2D Power Supply Issue

I have this LG TV. The PSU is fine, but because HDMI port is not functional, I want to use another universal motherboard for this TV, using this PSU for display lamps. Can somebody tell me what pins I need to connect to power On this PSU ?
The PSU have this pins on connector P201:
1. AC
2. POW
3. 5V
4. GND
5. INV
6. ERR
7. Bri
8. 5V
9. GND
10. DIM
11. 6V
12. GND
13. 3.4 O/F

Thankyou!

[dskall]

Re: LG 42LC2D Power Supply Issue

I would say pow to ground or around 3v depending on what state it is in plugged in.

[BMARo]

Re: LG 42LC2D Power Supply Issue

I would say pow to ground or around 3v depending on what state it is in plugged in.

Thanks, but INV ? It not necessary ?

[nomoresonys]

Re: LG 42LC2D Power Supply Issue

It is not clear what you are trying to do, can you go into detail?

[BMARo]

Re: LG 42LC2D Power Supply Issue

It is not clear what you are trying to do, can you go into detail?

Yes.
I want to remove the original motherboard, and replace it with this universal one. https://*******/3s8Pvxl
But because its power source cannot power the CCFL lamps, I want to keep the original power source board to power the display, and start this power source board through a relay controlled by the universal board. Or two relays if necessary. Basically those relays should open/close the contact between POW with GND or 3V and between INV with GND or 3V. But I don't know what contacts the relay should make for the power source to start and the display to work. That is my question. What contacts should I make on this source for it to start and operate normally without the original TV motherboard?
Thankyou

[nomoresonys]

Re: LG 42LC2D Power Supply Issue

Ok I see, maybe this will help, there's quite a few videos about the subject on youtube: https://www.youtube.com/watch?v=QzXpp6DyimA