Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

[imafan]

Hello,
I've always curious about component level troubleshooting and opportunity presented itself with this problem on my plasma TV. I would love your help in helping me diagnose and fix this. What I've observed so far:

Broken behavior:
- Everything connected, powering on produce a quick white noise and turn off immediately
- When i disconnect Y-sus, powering on has constant white noise but no picture. TV stays on
- When i disconnect just X-sus, powering has constant white noise and blotchy black and white on screen. TV stays on
- When i disconnect both, same behavior as disconnecting Y-sus

Observation
- All capacitors looks normal, no budging but i haven't test each one individually
- I tested the diodes on the powerboard and found one leaky one(multimeter show 4-7 both ways instead of normal 500-700 fluctuation, and 0 on reverse see pic).
- Tested the fuse and they seem to be ok

Question:
is it the y-sus or the power board with the malfunction diode?
Haven't taken the diode out yet, but where/which replacement should i get?
What else should i test for?

I'm new at component level testing so detail instruction/reference would be appreciated.
Thanks!
Billy

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

by x-sus i mean zsus(sticker on right board)

1. update* When i disconnect Y-sus (Zsus connected), powering on has constant white noise but no picture. TV stays on *for about 2 minutes then turn itself off again*

going through tutorial in https://www.badcaps.net/forum/showthread.php?t=18542&:

2. I checked the fuse (FS103) on zsus and it seems blown. touching the ends flash a random number on dmm and shows 1 leftside after. zsus FS104 is ok.

3. ysus fuses FS101,FS102, FS103, FS104 are ok (.5 values).
4. Vs and Va from power board is same as spec (Vs 203, Va 55)

Vsc and Vy- and Vzb, I have black probe touch metal plate and the red probe touch the +/- point where it says + Vxx -. Is this the right way to check voltage for these?
vsc and vy- seems low at these points
5. Vsc+(66), Vsc-(83)
6. Vy- (83) Vy+(96)

7. Vzb is 0!

So from finding #1,2, 7. is zSus the problem? solution: replace the fuse in #2 before trying to replace zsus?
What does #5 and #6 low Vsc,Vy mean?

Please advice before I proceed . Thanks!

[Hamie]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Disconnect the buffers,
And disconnect be z-sus,

Check the -vy by placing black probe on the - and red on the +

If vsc has similar test points do the same.

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

If disconnecting buffers, might be good to fully remove them just in case. Someone disconnected theirs on a PK series and sparks flew and damaged something. Not sure what went wrong there but there's a chance they needed to come out.

In the PK series guide it states to fully remove buffers if disconnected, not to run or it will cause damage.

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Vsc and vy- matches sticker. vzb, however, is 0. is it because of the blown fuse FS103?
* vsc =150
* vy- = -180

What do i look for after disconnect & remove the buffers?

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

ysus voltages retested ok via Hamie's instruction without disconnecting the buffers so i haven't disconnect them yet. anything else i should check?

[mmartell]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Probably blown igbt's on the zsus board. Replacing the fuse will just blow it again and possibly cause more damage. Use your meter to check for shorts on the devices attatched to the heatsinks.

[Shinju]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Check the solder points on the inductor coils on the Y-Z boards, these are known failures on this series of plasma panels.

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

took out the zsus board. found these two burned-looking small chips that's right under Q212 at the white right heatsink. What are they? replaceable or do i need a new zsus? Thanks!

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

took out the zsus board. found these two burned-looking small chips that's right under Q212 at the white right heatsink. What are they? replaceable or do i need a new zsus? How do i test these 3 prong components screwed into the heatsink? Thanks!

I'm going to suggest they were 2 x 10 ohm resistors, just probe all combinations of 2 legs in diode or continuity of that transistor and see if shorted. then do the same in resistance and post up the readings.

are the other 2 devices next to that transistor the same transitor type i.e the part number stamped on the case?

Do you have any scrap boards you could maybe pinch similar resistors from with 100 stamped on them?

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Actually I think I can just make out FGPF4533 x 3

http://au.mouser.com/ProductDetail/F...Qq3Co0Tw%3D%3D

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

those 3 will be working in parallel

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

part number on q212,q210,q208 is fgpf4633. diode mode all 3 chips beeps(shorted?) on various prong touches 004-018 range values. The other set on the same heatsink is silence.

on omh, values are about 9.6 when touching the legs

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

Do you have any scrap boards you could maybe pinch similar resistors from with 100 stamped on them?

i probably can find them on a motherboard. take these two out and solder two 100 in? they are very small, going to be tricky to take out/put in(never done before). any tips? do i need to replace the igbt as well?

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

i probably can find them on motherboard. take these two out and solder two 100 in?

I would not bother, they sound shorted. You could start with removing that transistor with the burnt resistors, then retest the other 2.

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

part number on q212,q210,q208 is fgpf4633. diode mode all 3 chips beeps(shorted?) on various prong touches 004-018 range values. The other set on the same heatsink is silence.

on omh, values are about 9.6 when touching the legs

I need you to be specific, are we talking the resistors or transistors? A 10 ohm resistor will beep and read close to 10 ohms, it's the "Q" device you need to check

[mmartell]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

...

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

I need you to be specific, are we talking the resistors or transistors? A 10 ohm resistor will beep and read close to 10 ohms, it's the "Q" device you need to check

reading is for the 3 legs Q transistors

[imafan]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

part number on q212,q210,q208 is fgpf4633. diode mode all 3 chips beeps(shorted?) on various prong touches 004-018 range values. The other set on the same heatsink is silence.

on omh, values are about 9.6 when touching the legs

I need you to be specific, are we talking the resistors or transistors? A 10 ohm resistor will beep and read close to 10 ohms, it's the "Q" device you need to check

These reading is for 3 leg Q transistors. Touched black on right leg, red on middle or left legs. all 3 Qs show similar values

[tw2005]

Re: Troubleshooting LG plasma TV 60PZ550 no picture, auto shutoff

These reading is for 3 leg Q transistors. Touched black on right leg, red on middle or left legs. all 3 Qs show similar values

ok, you'll need a new zsus or could see if you can get lucky with this one trying to repair it.

I'd remove that transistor that those burnt out reistors are andthe resistor too, then check the other 2 transistors again