LG 60PB5600 no video issue

[fconsela]

Hi all - my LG died while watching the other day. Ive searched the forum and found multiple threads with similar issues but cant seem to find one that is like what I am experiencing.

Here is where Im at:
1) PS voltages all look ok (VS, VA, etc...)
2) Zsus 18v reading 3.6v (my Ysus is cabled top the Zsus - not from PS board - still 3.6v with cable disconnected between Z & Y sus's)
3) Noticed that the green light on Tcon is not on
4) removed LVDS and tried to put into test mode using EXT-AUT-GEN jumped - no display.
5) looked very closely at all boards for blown caps - my aging eyes could not see anything blown or cracked.

Now I have read about Y-SUS can cause Zsus 18v to look bad, but the fact the that Tcon board green light never comes on has mew puzzled as to whether Im really looking at a Tcon issue or a Ysus issue (or Zsus...).

Cannot find any service diagrams or manuals for this model LG.

Hoping all you badcappers can provide some assistance.

[fconsela]

Re: LG 60PB5600 no video issue

Here is all the relevant info on my set:

Ysus: EBR77185601
Y-Buffer Upper: EBR77186101
Y-Buffer Lower: EBR186102
Zsus: EBR77185901
Tcon: EBR186601
Logic: EBT62854110

[dick_barton]

Re: LG 60PB5600 no video issue

Try the following website for the service manual.

Is the 18V supplied by the power supply or created on the Zsus board?

[fconsela]

Re: LG 60PB5600 no video issue

Thanks for the website will look for it today.

18v is created on the Zsus board ( I expect off the VA input).

[fconsela]

Re: LG 60PB5600 no video issue

Downloaded the service manual, however it contains no info (that I can tell) on Y & Z Sus's.....

Would first like to see why the Tcon green light isn't lit when turned on - any suggestions?

[dick_barton]

Re: LG 60PB5600 no video issue

Plasma sets are not my area of expertise but I would think you need to find out why the 18V is low. Use your meter and check the components attached to the 18V line to see if you can find what's pulling it down.
It may well be with that voltage being low, that the set is in fault mode and is why the logic board led is not flashing.

[fconsela]

Re: LG 60PB5600 no video issue

Any idea where I can find the schematic for the Zsus board? Not sure Im getting a good sense of how the 18v is created from just looking at the traces.

[dick_barton]

Re: LG 60PB5600 no video issue

Power supply and occasional main board schematics become available searching the web but rarely anything else. Generally repair by the skin of your teeth.

Using you multimeter start checking all the diodes, mosfets, resistors and 0 ohm resistors and see what you find.

[fconsela]

Re: LG 60PB5600 no video issue

SO I think I found the culprit pulling down the 18v on the Zsus. After reading many more threads on LG plasmas, I disconnected the Upper Y Buffer. Lower half of screen has flashing video and the 18v is present on the Zsus.

For fun I then reversed the situation and disconnected only the lower Y buffer (reattached the upper). Big bang and flash out of the upper Y buffer - smd cap blown off!

My excitement was short lived as I thought that I now created more damage so I disconnected the Ysus and checked all voltages on the PS board - all looked ok.

At this point I figure its best to just replace the whole Y board family (Upper and Lower buffer as well as Ysus). Does this sound like the right way yo go? Is it possible to just replace the Y buffers or does it have to be a package deal?

Also - shopjimmy is the only retailer that I can find that affordable with these parts, but they are out of stock. Any other place Im finding looks like the 3 boards will run me about $300 total and at that price I may opt for a new TCL. Any other affordable source for these boards out there?

As always - all comments appreciated.

[dick_barton]

Re: LG 60PB5600 no video issue

If when the Ybuffers only are disconnected and you have all the voltages are correct then I would be looking at replacing only the upper and lower buffers. Unless that is, someone with more experience can offer further advice.

[Mojobaggins]

Re: LG 60PB5600 no video issue

I believe my YSUS board is bad too on my LG Plasma. I found this service that will repair YSUS and buffers boards on eBay. It may be cheaper than trying to buy new ones.

https://www.ebay.com/itm/REPAIR-SERV...0/110535815308

[fconsela]

Re: LG 60PB5600 no video issue

Need some more advice - would a bad Y buffer and/or Y Sus cause my TCON board led no to light up? Would hate to spend any money on Y boards if there is a more pressing issue with the TCON light not illuminating.

[fconsela]

Re: LG 60PB5600 no video issue

Can anyone offer any insight?