LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component values

[neex]

Hi everyone - I was hoping that someone with an LG 37" (or thereabouts) with a EAX31845201/13 (Rev 1.2) PS board could verify a few values. I have countless schematics and have searched many posts, etc. and can't seem to find the matching schematic precisely.

R102 (it looks like maybe a 1/4 - 1W and based on what I've read/learned it sounds like it would be in the 1M range) - Can anyone help here?

Excuse the terrible pics of the other side (missing pad, flux, bad lighting)... Does anyone have the R213 and R216 SMD values?

If you have the same board and follow from R202 straight down, you will see two SMD resistors in parallel (just below the +leg of C204). Those are the ones I need to verify if possible.

Thanks for any help and sorry for the crappy photos - camera isn't charged so I had to use my cell.

Thanks!

[Fisher77]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

What is the model number of the tv?
Can you read the numbers on the R213, and R216 resistors?

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

What is the model number of the tv?
Can you read the numbers on the R213, and R216 resistors?

The model number is 37LC5DC and no I can't read the numbers coded on the smd resistors. I even tried with my optical microscope. The board was victim to a lightning strike/bad power bad protection so the R216 was blown right in half (if you look closely) and the other side is charred too much to read. The board is actually is pretty good shape for the few kv that likely hit it.... I'll see if I can clean it with some iso and look through the scope again....

clear as day now... used some lesser-than-top-shelf vodka as the iso was in the shop....

R213 is a 2200 .... R216 is blown to bits...

is it as simple as this: 220Ohm(2200) I feel a little foolish.... as I never thought it would be so easily cleanable....



Thank you,

A.

[Fisher77]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

I managed to find the value for R216. It is a 4701 or 4.7k.

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

I managed to find the value for R216. It is a 4701 or 4.7k.

Thanks so much Fisher77! I really appreciate this!

Here's hoping someone can help with the component-side R102 now...



Thank again!

A.

[Moreno83]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

I don't hope so but with lightning going through a power supply...there probably is more damaged then just that resistor....

Hope you get it to work!

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

I'm thinking the same thing but it looks shockingly clean (pardon the pun)

[Fisher77]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

Did the R102 get blowed apart also? I cant see it in your picture.

[Fisher77]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

Did the R102 get blowed apart also? I cant see it in your picture.

Ok, I found it on a picture of another board on the net. It is going to need a 1 watt. It was hard to tell exactly what color the bands are on the resistor, so a pic if possible would be good.

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

pardon the lint/pet hair under the tape..

[saddle_au]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

2c worth, shouting from the bleachers (did I get the reference right?).

Be careful if you are just replacing these resistors. Make sure you power it up away from the main and tcon boards. Check the 5v standby and enable the supply to see what happens to the other voltages.

I don't have that board in front of me, but it looks like it's in the area of the standby 5v feedback opto-coupler. Usually this just feeds into the driver chip (used to pwm into the gate of a high voltage fet) as a high or low pull when 5volts is at the right level on the secondary side. Since these resistors have met their maker, I would be suss on the driver chip (FAN7530 or whatever) as there was more volts than expected in this spot, more like mains voltage than lightning here. The sequence we see is:

- lightning causes over voltage which kills the fet (shorts normally to all pins)
- the dead chopper fet feeds mains to the driver chip through the the gate resistor and diode, which go next
- the driver chip fails and feeds high volts to all of the parts around it. Zeners for it's power supply, zeners on the current limit circuit, the feedback opto and it's open collector.
- The high voltage current limit/fuse 20 ohm resistor burns out to protect the transformer.

While not plugged into mains, put a variable power supply on the secondary side and turn it up slowly to 5v while measuring the opto led voltage and the opto output collector resistance. This will make sure the TL431 (or whatever is used on the secondary in the feedback) is also still functioning. If it isn't, you could be feeding higher voltages to the main board, which even temporarily is not good.

We always try to soak test power supplies for a day or more after lightning to make sure if they are stable, because some parts may be severely damaged but just functional for a while. This just needs some load for the 5v, 12v and 24v outputs.

[Fisher77]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

R102 = 750K, 1 watt 5%

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

Thanks again for all the comments and help! I have a decent 3 channel power supply that will do nicely for this and also have a variac and a train controller that do in a pinch. I will update this thread as I make more discoveries.

Thank you,
A.

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

R102 = 750K, 1 watt 5%

Hello again Fisher77-
I don't suppose you have an accurate schematic for this SMPS? I have some nackered pads and was hoping run a jumper from C204. It looks like I can jump the leg from C204 neg to R216?? Apologies if this sounds disastrous....


Thank you,
A.

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

Just a quick update... I was able to get the SMPS back online and all voltages to my knowledge check out fine. The set comes on and I am unable to power it off with the power button.. volume control doesn't work and neither do source selections.... I only get fuzz and 'white noise' audio.

Here are my readings from P201 and P202

202
(1)19V - 20.6
(2)19V - 20.6
(3) GND
(4) GND
(5) 6V - 6.09
(7) GND
(8) 3.4V - 3.46
(9) GND
(10) 12V - 12.8
(11) GND

P201
(1) 3.4V (1.94 with connector unplugged and 3.46 with it plugged in)
(2) GND
(3) 6V - 5.96
(4) DIM -
(5) GND
(6) ST/5V - 4.97
(7) I.B. - 1.69
(8) ERR - .013
(9) IC - 4.8
(10) GND
(11) ST/5V - 4.96
(12) ON - 2.69
(13) ACD - 4.21

measuring from one side of the ground plane to the ground screws is pretty consistent at .036V...

Any ideas? I feel like I'm pretty close here....

Thank you,
A.

[neex]

Re: LG LCD 37" EAY3306450/EAX31845201/13 (Rev 1.2) - please verify a few component va

please ignore last request as I made another thread for the issue - apologies on that one mods....