LG 42 Plasma TV 42PC3D No picture Yes sound

[8cuda]

My first attempt at a Plasma TV with issues.
No picture
Yes sound

one cap look to be bulged on the power supply
voltages check out at the connectors on each of the YSUS and ZSUS boards
voltages at the fuses check out on the YSUS board
voltage at one of the fuse on the ZSUS board
no voltage at one end of the fuse on the ZSUS board

should the IPM on the ZSUS board changed?
or
should the ZSUS board be changed?

Which caps should be replaced on the power supply?

[8cuda]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Replaced the bulged cap on the power supply board
Replaced the z sus board with used board from ebay

The plasma TV now shows picture, but it has the red speckle issue.
Possible Firmware issue.

[drpj23]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Make sure the voltages are in spec to the sticker and that may get rid of a good deal of them.
tom66 may know how to also alter the voltages to get the best pic.
But, yes firmware is probably an issue.

[jamesharris]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Replaced the bulged cap on the power supply board
Replaced the z sus board with used board from ebay

The plasma TV now shows picture, but it has the red speckle issue.
Possible Firmware issue.

Red speckles can be an aging panel. Do they disappear as the set warms up? First thing to do is adjust one of three pots on Y SUS board. Can't remember which one. One is called setup and there are two others nearby. Slowly turn each one until you see them (speckles) reduce. I think a side effect of this is a reduction of resolution so it's a bit of a compromise depending on the age of your set.

[tom66]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Setup/Setdn and Ramp are the appropriate controls.

It doesn't reduce resolution, maybe can cause some lag on frame changes but that's usually rare.

[jamesharris]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Setup/Setdn and Ramp are the appropriate controls.

It doesn't reduce resolution, maybe can cause some lag on frame changes but that's usually rare.

I've seen it operate like a focus pot where there is a noticeable change in image sharpness but may have been an aging panel issue as previously mentioned.

[tom66]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

That sounds more like a CRT than a plasma display. A plasma display has fixed pixels, and hence a fixed resolution. No contamination can occur between pixels, as far as I am aware.

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Setup/Setdn and Ramp are the appropriate controls.

It doesn't reduce resolution, maybe can cause some lag on frame changes but that's usually rare.

How much am I allowed to turn those? I get a slightly better picture when turning setup and setdn to the end. How do I completely get rid of this red noise?

[Alastair E]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Red-spots means that the Firmware on the Control-Board needs updating.

Adjusting SET_Up/SET_Dn and Loweing the Vs by 5V can help but wont completely remove the spots in most cases. Altering these pots will have Zero effect on resolution.--apart from the reduction in spotting (Mal-Discharge = correct name) the only other visible effect is a difference in peak black-level.

A L.G. Jig is needed to load the new firmware version direct into the Control-Board

Depending on where you are, 'Capkid' in the USA can do it, and I in the UK can do it as we both have the required equipment.

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

What does the new firmware do?

[Alastair E]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

New F/W alters the timing and duration of the set/reset pulse to accomodate for panel age.

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Ok so the real cause is panel aging. The firmware does the same thing as the two pots setup/setdn but outside the boundaries of these two pots?

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Can't the thing the software does not be done via a hardware mod?

[Alastair E]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Ok so the real cause is panel aging. The firmware does the same thing as the two pots setup/setdn but outside the boundaries of these two pots?

No--The Pots merely control voltage levels of the waveform and have no effect on timing and duration.

On the X3 chassis (like this one) I compared the waveform of un-modded and the new modded firmware.
On the rising ramp, there's a negative spike approx halfway up. This is modified to make it a much wider step, and in a slightly different position, before the ramp then continues to rise.

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

No--The Pots merely control voltage levels of the waveform and have no effect on timing and duration.

On the X3 chassis (like this one) I compared the waveform of un-modded and the new modded firmware.
On the rising ramp, there's a negative spike approx halfway up. This is modified to make it a much wider step, and in a slightly different position, before the ramp then continues to rise.

I assume you didn't save the scope screenshots anywhere? :-)

Would be awesome if there was a way to do it other than by means of a firmware change. On the other hand these panels are so "old", it's hardly worth it.

[Alastair E]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

No--Didnt save any pictures--didnt take any! I have a 'Proper' scope, not a PC base one....

IF there was another simpler--adjustment based/change/add/delete component--method of fixing the issue--I'm sure LG would have gone that route rather than have to develop and distribute two types of rather specific jig and firmware files to sort the issue permanently....

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

No--Didnt save any pictures--didnt take any! I have a 'Proper' scope, not a PC base one....

IF there was another simpler--adjustment based/change/add/delete component--method of fixing the issue--I'm sure LG would have gone that route rather than have to develop and distribute two types of rather specific jig and firmware files to sort the issue permanently....

Ok, thanks,

these jigs, how complex are they? Is that something we HAVE to buy or is it something only authorized service centers have access to?

Just guessing here but isn't it just a simple programming adapter?

Can you share what you have (including firmware) or is that not allowed?

EDIT: I see a jig costs around 200 US. Double the price the TV is worth...

It certainly does not make sense to pay someone here in Canada to do this. Here everything is either expensive or imported or not available or all of it. :-D

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Anyway, I found a pic of the jig, looks complex enough. :-/

http://www.brelect.fr/index.php?page...20MALDISCHARGE

In theory, if it's only a certain memory chip on the control board, it should be possible to remove that chip and use another flashing tool. In theory at least. IF one has the correct firmware.

[Alastair E]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Well--Sure, I can send you the F/W files--no problem, the files I have cover a fair number of sets.
(Unfortunately--NOT a file I need for a more recent set though!)

The kit you linked to is what I have,--Although, that supplier doesn't show any CD-Rom containing the Software (For the PC) and the F/W files needed.
Somewhere on web--in that stupid 'Scribd' thing there's a copy of the procedure/instructions for use of that jig, but you have to pay for the complete version on there.
--The PC S/W and Jig will ONLY Operate on a 32 bit PC system with USB.....

I can send what S/W etc I have though, including that....

I'm not connected to LG--or any other makers--and have aquired the complete kit from a guy who was once a dealer....

[paulstef]

Re: LG 42 Plasma TV 42PC3D No picture Yes sound

Well--Sure, I can send you the F/W files--no problem, the files I have cover a fair number of sets.
(Unfortunately--NOT a file I need for a more recent set though!)

The kit you linked to is what I have,--Although, that supplier doesn't show any CD-Rom containing the Software (For the PC) and the F/W files needed.
Somewhere on web--in that stupid 'Scribd' thing there's a copy of the procedure/instructions for use of that jig, but you have to pay for the complete version on there.
--The PC S/W and Jig will ONLY Operate on a 32 bit PC system with USB.....

I can send what S/W etc I have though, including that....

I'm not connected to LG--or any other makers--and have aquired the complete kit from a guy who was once a dealer....

That sounds great , I'll have a look what board exactly it is, panel number etc and PM you. Thanks