A guide to fixing/troubleshooting some common plasma TV problems

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Hi,
Tom said "post a thread - the problem is more complex" so here goes...

- LG 42PX5D
- exact history detail unknown as its a donation to me
- powers on ok
- image shows as lilac (purple,reddish) just as described in first post of this thread about z-sustain failure
- fuses on z-sus are ok
- power supply voltages all appear in spec
- issues is hard regardless of input or settings

Suggestions?
Thanks
M

Z-sustain ER-IPM failure or Vzbias failure. Replace Z-sustain, or replace IPM.

[DFM379]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Yes, that IC is definitely very bad.

The drive board (when it fails) usually kills either: all the ICs, or the top/bottom most IC. It's very rare for one in the middle of the pack to fail. And as far as I am aware, like most well designed TVs, a failure in the drive board on a Pioneer does not damage the buffer ICs.

You should only need to change the lower board... however, if you've got both, swap both for longevity.

I hope the panel is OK, because I know some Panasonic panel failures can damage the buffers. But I thought it only happened to certain older series. Don't have much info on Pioneer unfortunately.

Last question - If I swap the Y drive with a used Y drive from another monitor will I need to perform any adjustments? The set was ISF calibrated and I am hoping that will be retained.

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Last question - If I swap the Y drive with a used Y drive from another monitor will I need to perform any adjustments? The set was ISF calibrated and I am hoping that will be retained.

It would need to be adjusted to the voltages specified on the plasma panel, which can be done using the service guide. PSU produces Vsus and Vdat (for horizontal and vertical electrodes), then the Y-drive usually produces the scanning, erase and reset voltages. So there's at least five you need to check and set to factory settings (using a calibrated +/-1% DMM.)

You would need to verify the calibration again though, if that mattered to you, as each board has slight variations. I'm not a videophile, so I don't know to what degree it matters if the calibration is a few percent different. I've never calibrated a set myself.

[m4malious]

Re: A guide to fixing/troubleshooting some common plasma TV problems

...Some more info on this one...

- the Vz-bias is ok at 100v

- the Vsc and -Vy are completely down - and jumping around the 5-60v
range. The meter shows they change approx ever 1/3 second.

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Can I see a picture of the defective picture?

[m4malious]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Tom,

Looks exactly like the images at
http://www.austech.info/electronics/...e-problem.html

- no signal input
- on power on the screen populates image from RHS slowly filling over to LHS
with noise from zero input
- takes about 3 minutes for whole screen to show constant image
- pink (purple, lilac) all the time
- image dim (max. contrast,colour, brightness are set via OSD)

Thanks!

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Definitely z-sustain then.

[DFM379]

Re: A guide to fixing/troubleshooting some common plasma TV problems

It would need to be adjusted to the voltages specified on the plasma panel, which can be done using the service guide. PSU produces Vsus and Vdat (for horizontal and vertical electrodes), then the Y-drive usually produces the scanning, erase and reset voltages. So there's at least five you need to check and set to factory settings (using a calibrated +/-1% DMM.)

You would need to verify the calibration again though, if that mattered to you, as each board has slight variations. I'm not a videophile, so I don't know to what degree it matters if the calibration is a few percent different. I've never calibrated a set myself.

Hmmmm - but if it came from the same model (Elite FHD1) shouldn't the voltages be within the specification?

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Every plasma panel is slightly different and the settings are different for each.

[m4malious]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Y-sus power generation issues - advice needed;

LG 42PX5D-AB

- unit powers on and will stay on
- image is dim and pinkish
- no signal input image is snow and populates screen from Right to Left slowly
- after about 5 minutes, whole screen is showing a pink, snowy pattern
- reception seems poor (might be antennae) - with metal back off, picture and sound come and go

Whats been done;
- cables reseated on power and all boards - no change
- power supply voltages measured - in spec
- zsus fuses measured - ok
- zbias voltage measured - in spec
- ysus fuses measured - ok
- yvsc measured - low, cycling around 2,10,60v, every 1/3 second
- -vy measured - low
- y-buffer board removed - y-sus voltages still low

- other comments say "z-sus suspect" but the y-sus has the obvious fault
- not interested in board swap - capable at component replacement so want to do that

Anyone got any advice in terms of likely components to check?

Thanks
M

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

The Z-sus IPM can fail without shorting.

You should check the voltage across the ERC caps. If you need help locating these post a picture.

[DFM379]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Well I received and installed the lower scan board today and everything looks perfect. Instead of the Y drive I was sent the x Drive by mistake so I guess I got lucky.

Ran through the Digital Video Essentials DVD and it seems everything is still calibrated correctly.

Thanks for your support!

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Glad to hear everything is working nice. I'm just getting used to the black level on a Panasonic TH-46PZ80. It looks nice (wayyyy better than any LCD/LED, and most other plasmas I've seen), but I'm sure it's nothing compared to the Kuro. Enjoy the TV.

[m4malious]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Hi Tom,
I do really appreciate the responses - can you add on the following comments;

>The Z-sus IPM can fail without shorting.

I plan to replace the IPM on the Z-sus and retest, as first component replacement.

>You should check the voltage across the ERC caps. If you need help locating >these post a picture.

ERC? Not familiar with that term.
You mean on the Y-sus where the Vsc and -Vy are low?
Meauring across caps on that looks tough, given its mounted and always so behind the control board chassis.

Thanks
M

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Sorry, energy recovery caps. On an LG they are usually the long row of red ones... sometimes there are two, one for ERC and one for VSUS.

[DFM379]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I never quite understood why Pioneer decided to discontinue making Plasma TV's. I bought mine 7 years ago when they were the top rated manufacturer. I can honestly say its twice as good as any of the other sets I have purchased or seen since.

I'm thrilled I was able to get this issue resolved.

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

I never quite understood why Pioneer decided to discontinue making Plasma TV's. I bought mine 7 years ago when they were the top rated manufacturer. I can honestly say its twice as good as any of the other sets I have purchased or seen since.

I blame it on LED TVs. They're technically inferior but everyone thinks they are the "next best thing".

My brother has a 46" Samsung LED TV, top of the range smart TV.

The picture is worse than my dad's 6 year old NEC 50" plasma that I fixed for him. Pioneer bought NEC's plasma division to spin it into their own so it's using pre-Pioneer tech. And it looks very nice indeed despite its age. Only major loss is it's only 720p, but it still looks nice on HD.

Plus the market for Pioneer plasmas was high end. They needed to market some "not so good but better than the competition" plasmas, yet they failed to recognise the demand.

OLED is the only thing that'll beat plasma (or FED/SED, if they ever come to fruition), but they are a long way away. Once affordable OLED is reached, I predict that they'll be another technology stagnation much like there was with the good old CRT. Infinite contrast, microsecond response time, high brightness, high fidelity, low power, ultra thin... where do you go from there?

[m4malious]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Gosh...here's a noob question;

What are the small drop-like, orange coloured components, labelled with "B"
on these boards? Look like small tantalums, but legs are arranged at right angles and the ball of the component is to one side of the legs.

Am down to circuit troubleshooting 101 I figure...

[tom66]

Re: A guide to fixing/troubleshooting some common plasma TV problems

They are ferrite beads. Basically they filter some of the higher frequencies created when sustaining the plasma panel.

[kkanc]

Re: A guide to fixing/troubleshooting some common plasma TV problems

Hi Tom. Your guide on the troubleshooting of plasma tv's is great. I've learned alot so far but have a great deal more to learn before I'm really up to troubleshooting. At this point I'm probably doing something wrong with the guide. I'm new to this and don't have a great deal of experience troubleshooting boards. I'm more into mechanical. I have a vizio plasma JV50P HDTD10A serial PHLANAH1801xxx The original problem from reading was the sound would go on and then off with a loud noise. Then off and on with the tv. Then would work normal. Did this a few weeks. Now tv would not even turn on. Yellow vizio label would not turn white, no click, no sound. Took off back of tv, read many items on internet, wish I would have found badcaps first. I did see caps on power board were leaking bad. Replaced that board. Was able to then get tv to turn on, yellow vizio turn white and you can hear a click. Still no sound or picture. From what I had read elsewhere, I replaced the main board. I still have no sound or picture. You can hear a slight crackle from speaker when turned on but that's it. I found this website and tried your troubleshooting guide but didn't seem to help pinpoint anything else wrong. I know I must be doing something wrong. I have noticed that I believe there use to be a small red light that could be seen when using the remote, that is no longer doing that. Batteries have been changed and does turn tv on and off, but I have been using side controls of tv during testing. Any other possible tests or retests that I could try. I did check the few fuses that I could find (regular fuses). As I say, I'm not really into board troubleshooting but learning from the posts on badcaps. Thanks, Ken