Y-SUS repair (EAX64282201) (LG Plasma)

[tofik]

Hi,

I believe many people here have an experience with a broken YSUS module so I decided to create a new thread.

I got a LG plasma which is dead after a power spike, mainboard and logic has been already replaced, PSU is fine.

Now I am (at least) trying to fix Y-SUS which is EAX64282201.

What I already found:
- two traces were damaged like on the picture below, I already fixed them,
- diode D562 is damaged (resistance 0 ohm),
- visibly nothing else looks bad on the pcb,


I tested all transistors for shorts to gnd and also between drain/gate/source. Resistors, diodes and capacitors also has been tested for shorts.

- diode D256 is 3 ohm (test on the pcb so far), probably also damaged,
- transistor Q509 - all legs shorted, took it off from the pcb, tested again, confirmed > all legs shorted,
- also found a short on Q401 + Q402 + D401 - desoldered them all, tested and Q401 + Q402 are definitely damaged (short between legs number 2 to 3), D401 seems to be fine.

The rest of the transistors seems to be okay, no shorts to gnd and no between their legs.

Did not test the smd resistors linked to IGBTs yet.
About switching optocouplers (TLP105) - what's the easiest way for testing them?

Any suggestions what to check now? I don't have any obvious shorts on this PCB now but feel there will be something else damaged, what do you think?

Q401 and Q402 are both RJP63K2, Q509 is: K8A60DA.
Any chance to test PDP without them?

some photos:

[SluggerB]

Re: Y-SUS repair (EAX64282201) (LG Plasma)

I am working on an LG plasma, and found this PDF to be invaluable

https://www.badcaps.net/forum/attach...3&d=1517627618

In my case I found a total of 8 IGBT's that tested bad. I have replacements on order, don't know i that is the issue or not

[tofik]

Re: Y-SUS repair (EAX64282201) (LG Plasma)

Thanks for your message and pdf, definitely will have a look.

So in your case 8 igbts were damaged and what else?

[SluggerB]

Re: Y-SUS repair (EAX64282201) (LG Plasma)

Thanks for your message and pdf, definitely will have a look.

So in your case 8 igbts were damaged and what else?

That's all I have found so far. All voltages coming from the power board are correct, but the control board dies not turn on. The control board gets it's power from the Y board, and when I found bad igbts there, that was the first thing I ordered up.

The main board could be bad, and I am going to reflow both boards even though under my microscope all the joints look good some people have had luck refloeinng boards with no visible bad joints