LG 42PC3D-UD plasma

[PlainBill]

This is another Craigslist bargain. The original owner indicated it was working perfectly, then one day it would not turn on. He loaded it up and took it to a shop where for $50 they told him it needed a Y-Sus and the Y buffer. Total cost to repair was unreasonable, so he put it up on Craigslist.

A quick check shows this is one of the models with the infamous Y-Sus failures. Remembering Wizards recent posts, I opened the set up and checked the fuses on both the Y-Sus and Z-Sus boards; both are good. Then I checked the power at both boards (AFTER the fuses) and I see both voltages as specified on the sticker. 5Volts also checks out.

The only other item of note is a red haze or sparkles on the right side of the screen. It's only visible in low light conditions, and even then doesn't show up too well in the picture I attached. (Ignore the guy reflected in the screen, he's just an old coot who lives here).

Is this a sustain or buffer problem, or is it a panel failure? I do have a scope available, but the awful Korean / English training manuals give me a headache.

PlainBill

[Wizard]

Re: LG 42PC3D-UD plasma

That where you need scope. Scope the TP test points on the Y buffer for good pulses (notchy with ramps that goes 45 degrees up and 45 degrees down).

Sometimes this fails without blowing the fuse. Scope will confirm. Also scope the LVDS that you are getting signal to the logic board.

training book on LG but not like your but it applies to yours. The panel is samsung in fact.

http://www.scribd.com/doc/7580885/LG...raining-Manual

Cheers, WIzard

[PlainBill]

Re: LG 42PC3D-UD plasma

Well, a little (darn little) progress has been made. A bunch of brain cells got together and stirred up the idea of our Super Nintendo to the AV1 input. As you can see, a badly distorted image is visible.

The pictures in order are:
1. Screen shot
2. Back of the set with cover off (Yes, it's unplugged).
3. Labels on panel
4. More labels on panel
5. The Y-Sustain board and the Y-buffer (driver?) board
6. The upper portion of the Y-Sustain board and a portion of the buffer. (Wizard, is the 'Waveform' test point significant?)
7. The lower portion of the Y-Sustain board and a portion of the buffer. Note a bunch of pots I did NOT touch.
8. Detail of the lower portion of the Y-sustain. Note label indication test points for VY and pins carrying Vsc to the buffer.

I've gone over the training manual you referenced, Wizard, but while I've gleaned a few bits of information, I'm nearly clueless about what I am seeing. The two things that come to mind is this is probably not a problem in the main board or the panel control board. The video is being passed to the display. The second is this seems to correspond to page 33 of the Training Manual. Should I be measuring Vscan? Checking the Waveform test point with my scope? I do have it at hand, but I would rather not subject it (or myself) to 200 volts.

PlainBill

[PlainBill]

Re: LG 42PC3D-UD plasma

I'm shooting in the dark here (literally, the lights in the room were off when I took the following pictures to reduce screen glare). The waveforms were taken at the point on the buffer board labeled 'Waveform'. The scope settings are noted on the pictures, as well as the approximate 0 Volts point. The TV was showing the opening screen of the Super Nintendo game 'The Lion King'. (And I've got the theme engraved in my mind - HELP!!!)

The ideal waveform is also included. The obvious difference is the plateaus shown in the ideal waveform are not present on the actual waveforms. I'm not sure if this indicates a problem in the buffer (driver) board, a problem on the Y-Sustain board, using an incorrect input signal, or other user error.

Vsc measured 124 Volts and -Vy was -199 Volts.

PlainBill

[Wizard]

Re: LG 42PC3D-UD plasma

I think this is taken with white field or black field on the screen. Does not look quite right.

Move around probe test points till you find one that look right. Usually on the Y-buffer board.

Cheers, Wizard

[PlainBill]

Re: LG 42PC3D-UD plasma

I think this is taken with white field or black field on the screen. Does not look quite right.

Move around probe test points till you find one that look right. Usually on the Y-buffer board.

Cheers, Wizard

Thanks, Wizard. The set is buttoned up right now. I'm waiting for delivery (due today!) of a LJ41-04220A for another TV, and that takes priority.

One thing that is frustrating me is that the only manuals I've found to explain what is happening on plasma panels are those from LG. And they look like they were written as a handout for a class; not as something to be used for self-education.

PlainBill

[cadiman]

Re: LG 42PC3D-UD plasma

All of these boards look the same as mine vizio/lg. y and z, also power board looks the same. I couldn`t see your pictures before ( was not a member at the time). scope pattern looks better than mine. I will look at said manual for more info. Iknow this is on your back burner for now, but it`s nice to see the same tv I have on here! I am not a parts hanger, but I think I will be replacing more boards than I want to. I will get my camera soon on here.

[PlainBill]

Re: LG 42PC3D-UD plasma

All of these boards look the same as mine vizio/lg. y and z, also power board looks the same. I couldn`t see your pictures before ( was not a member at the time). scope pattern looks better than mine. I will look at said manual for more info. Iknow this is on your back burner for now, but it`s nice to see the same tv I have on here! I am not a parts hanger, but I think I will be replacing more boards than I want to. I will get my camera soon on here.

I've got some more information on this project. I was able to pick up the 'big brother' to this one, a 42PC1DA which had a shorted Z-Sus board. I discovered I could buy a new Z-sus cheaper than than having the old one repaired. Right now I'm waiting on delivery of that module.

While digging for information on it, I came across this document: Lg Plasma - Quick Reference Alignment Hand Book, item # 19532668 on Scribd. It contains a wealth of information on setting up the set. Scribd also has a number of training manuals for other LG panels. Unfortunately, I still have not been able to locate the training manual for this particular panel. However, with one TV working I hope to be able to troubleshoot and locate the defective module - and maybe even fix it!.

PlainBill

[PlainBill]

Re: LG 42PC3D-UD plasma

Well, we are making progress. I was able to purchase a pair of NEW Z-sus boards for a company in Miami at a ridiculously low price. I now have a pair of working 42" LG plasma TVs. I was thrilled to discover that the 42PC1DA had less than 700 hours on it, and a fantastic picture.

The 42PC3D-UD didn't turn out quite so well. It has over 9000 hours on it. While it will blow away a CRT TV, there is a slight pink tint to the screen, especially noticeable when I set it to display a white screen. The service manual does give instructions on adjusting this. The first paragraph begins

7-1. Required Equipment
(1) Color analyzer (CA-100 or similar product)
(2) Automatic adjustor (with automatic adjustment hour
necessity and the RS-232C communication being possible)
(3) Pattern Generator(MSPG-925FA): DVI Output

Wizard, is there any safe way to tweak the setting manually?

PlainBill

[Wizard]

Re: LG 42PC3D-UD plasma

Use grey scale bars and adjust for white and untinted grey. That is done with rgb drive and low light rgb adjustment in the service menu.

Pink is worn out panel 9,000 hours is what does it especially on torch mode.

60% of people don't care and watch it regardless. :P

Cheers, Wizard

[kolodza]

Re: LG 42PC3D-UD plasma

plainbill,
i think im having about the same problem with my lg plasma 42pc3d.
can you tell me more about the sweet zsus boards you snagged up?
how hard is it to switch one of those out? i have no training, just desperate.
i have a post here with a pic of my tv if your curious
thanks

[PlainBill]

Re: LG 42PC3D-UD plasma

plainbill,
i think im having about the same problem with my lg plasma 42pc3d.
can you tell me more about the sweet zsus boards you snagged up?
how hard is it to switch one of those out? i have no training, just desperate.
i have a post here with a pic of my tv if your curious
thanks

How skilled are you? The biggest problem with swapping a z-sus is getting the back off - LOTS of screws. There is one voltage that has to be adjusted on the new one, but all that requires is a DMM and a small insulated screwdriver.

That deal is no more. Someone was dumping a log of new old stock. They are gone now and the buyers are marking them up 50%.

PlainBill

[kolodza]

Re: LG 42PC3D-UD plasma

im not sure how skilled i am but i did take the back off and thats when i decided that changing out a board didnt look that bad,
now i cant tell you which is the zsus or the ysus but im thinking the ysus is the board thats connected to the buffers...
but i may be totally wrong,
im working on getting some pics on here of the opened back,
but my card reader is acting up, so i cant upload the pics
i will follow up with pics when i can,,,
this is how bad i am,, whats a dmm??
the zsus boards i looked at were 137$,, is that a good price?
thanks,,,,,,,

ps, i just looked back up at your pics and my tv is identical to the one you posted,, even has the electrical tape in the same places!, ha!
im gonna use it as ref in my other post, if thats ok till i get mine uploaded

[cats]

Re: LG 42PC3D-UD plasma

guys, nice tread! im having a simular problem. wile looking at tv heard a pop discovered a fuse in the ysus chanced the fuse and it keeps popping,the tv would not come on just a click. i decided to changed the ysus now ths set is coming on but no picture and no sound the screen will light up a little kinda looks like a backlight is on. please help......

[retiredcaps]

Re: LG 42PC3D-UD plasma

please help......

Multiple posts are frowned upon here because it creates confusion and extra work for everyone.