Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Here are the test points from the service manual.

Should i use chassis for ground?

Thanks

Yes, just place the black probe on the back of the plasma panel, the wall mounts are a good location.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Yes, just place the black probe on the back of the plasma panel, the wall mounts are a good location.

I did first VSUS voltage test tonight.

Sevice manual says 193v plus or minus 2v for VSUS

VSUS voltage at the test point on the SC board is averaging 191.6v But i seen it drop as low as 190.8v and a max of 192v

When i turned tv off with DMM still connected it took about 4 min for voltage to drop to around 1v so i could disconnect meter(Im using grabber clips on my DMM)

Now voltage at VSUS test point on the SS board was strange,It was bouncing all over the place from 0v to a max of about 120v never settled on any one number,but when i turned off tv it went to around 180v and started a steady decline down to 0 as the capacitors discharged just like it did on the sc board.

Not sure if that is normal or not?

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I had a panasonic where the VAD had dropped to the low point of the protection cct cutoff and gave 7 blinks. i could sometimes get the set to fire for a short period and picture was a little dim and slight flicker.

Fixed with Sc replacement. Pot made no difference on that board and could not pin it to a single component. Bypassed the shutdown cct to get the set to fire just to confirm it was just the SC board.

I don't know what the limits are but you havethe manual so there should be enough info in there. I'd check the test points on the SC. The schematic shows all the voltages that are part of the SOS7.

Thank you for the information!

All i really know is VSUS is suppossed to be 193v plus or minus 2v.

Im new to working on tvs so i really have no idea what im doing,but im trying to learn with all the help from you all here on this site

My tv only shuts off occasionally,maybe around 1 time every 10 hours of operation

When you say, ''the VAD dropped to the low point of the protection circuit cutoff''
What is VAD and is it the same as the VSUS voltage?

Thank you

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

VAD is the horizontal address supply, it is different from the sustain voltage VSUS.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I did first VSUS voltage test tonight.

Sevice manual says 193v plus or minus 2v for VSUS

VSUS voltage at the test point on the SC board is averaging 191.6v But i seen it drop as low as 190.8v and a max of 192v

When i turned tv off with DMM still connected it took about 4 min for voltage to drop to around 1v so i could disconnect meter(Im using grabber clips on my DMM)

Now voltage at VSUS test point on the SS board was strange,It was bouncing all over the place from 0v to a max of about 120v never settled on any one number,but when i turned off tv it went to around 180v and started a steady decline down to 0 as the capacitors discharged just like it did on the sc board.

Not sure if that is normal or not?

Here is what i found for Vsus voltages,not sure if you seen it or not

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

My first voltage test on VSUS last night is reply #22 (just wanted to make sure you seen the results)

Tonight i borrowed some different DMM probes so that i could use my new/better Dmm with my grabber clips( grabber clips wouldnt fit on my new meters probes)

I also set up the DMM and tv so i could watch the tv and monitor the voltage tonight.

My new meter is giving slightly different voltage 192.7v ( as opossed to 191.6from last night with my cheap meter)

VSUS = 193v is what the sticker on the tv calls for.

I watched the tv and meter for 3,40 minute sessions and the VSUS voltage was pretty stable from a low of about 192.2v during bright white scenes to 192.8 for dark scenes. 192.7 average most of the time.

But 4th session i stayed on a channel that had a infomercial that was bright white, and yeah you where right Tom the voltage started to drop to as low as 175v with colored pixels on the screen (see pic)

For about 20 mins the voltage was unstable going anywhere from 175v to back up to 192.7 ,But the tv never shut down.

After about 20 min the voltage became stable again at 192.7 and tv is still going and has not shut off yet.

So yeah,Wild readings last night on the VSUS test point on the SS board,and tonights readings at the VSUS test point on SC board going as low as 175v.

What do you think is going on?

Have infomercials ruined this tv LOL! And sorry about the creepy pic LOL(its the only one i could get showing the image starting to act up)

Thanks!

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I have seen the same symptom before on a Pioneer plasma - picture started going wonky as the supply dropped out.

Try taking some contact cleaner and spraying it in the VSUS adjustment pot. Turn the pot back and forward a few times to make sure all of it gets in there. Then re-run the test.

[tw2005]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Bottom half looks good, top half not good. My first guess would be the SU board. 7 blinks covers SC,SD,SU boards.

Maybe this what is shutting it down. probably starting to fail and loading up the SC board taking the voltages down with it.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I have seen the same symptom before on a Pioneer plasma - picture started going wonky as the supply dropped out.

Try taking some contact cleaner and spraying it in the VSUS adjustment pot. Turn the pot back and forward a few times to make sure all of it gets in there. Then re-run the test.

Would that be the VSUS adjust pot on the power supply board?

Should i make a mark on the pot so after i cycle it i can put it back in its original spot?

Will i need to reset the VSUS voltage after cycling the pot( im inexperianced of how sensitive that pot is ,can i do damage by the voltage being too high or low?

I have CAIG DEOXIT contact cleaner ,that should work right?

Thanks Tom

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

You can do it with the TV plugged in. Turn it in the direction that goes down (try both ways.) Picture may go funky this is OK. Then, turn the TV off (unplug it.) Spray the cleaner in there; turn it back and forwards a few times, repeat this spray and turn cycle a few times. Allow the cleaner to evaporate for 5 minutes. Plug TV back in and check voltage, adjust it to the sticker when the screen is displaying ordinary program content.

Take note about the upper portion, as tw2005 mentioned. It does look like it could be a fault with the upper buffer, maybe an intermittent fault. Are there any missing lines on the screen at all?

If that cleaner is safe on plastics, it should be fine.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Turn it in the direction that goes down (try both ways.)

So I should back it down a bit then do the cycling,staying down lower than the original position? Or should i cycle the full range of the pot?

Take note about the upper portion, as tw2005 mentioned. It does look like it could be a fault with the upper buffer, maybe an intermittent fault. Are there any missing lines on the screen at all?

No there are no missing lines, picture is perfect.

I was able to catch it tonight turn off watching the DMM, it went down to 150v and the screen was almost completly dark ,then it shut off.

The screen does get funky first at the top ,but it soon drops to the bottom of the screen then the whole screen starts to go dark evenly,

I caught a pic just before it turned off ,not a great pic but should give you an idea

Thanks

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

So I should back it down a bit then do the cycling,staying down lower than the original position? Or should i cycle the full range of the pot?

Return the pot to the original 193V setting once you have done the cleaning.

It definitely looks like insufficient Vs problems. The Pioneer I serviced though
would still have some visible discharge at as low as 130V, but obviously, very poor image.

[tw2005]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I believe on these earlier models you can isolate either buffer board and fire it up and get half a picture.

If the VSUS fault finding shows nothing concrete maybe try the set with just the lower and see how stable it is. Then try just the top and see if the fault replicates itself.

You just have to love intermittent faults.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Earlier today i cleaned and cycled the pot with deoxit (sprayed it in the hole with a straw where the screwdriver goes and the spray came out the back of the pot, so i think i got it in there good)

Sprayed and cycled 3 times, and reset the VSUS voltage back to 193v,And did 3, one hour long tests with no problems,but on 4th test she shut off ( another one of those infomercials with lots of white background)

But this time when it shut off the screen did not get funky or dim it just shut off ( of course i didnt get to see the voltage on the meter as it has a auto off function,and my meter had just shut off not more than 30 seconds before the tv shut off ,figures LOL)

You all think i should try unplugging the SU then the SD board one at a time, as TW2005 suggests and see how that goes?( I not sure of the procedure on unplugging them,and which plugs to unplug)

SU and SD boards at shopjimmy are only 30 bucks each,and i think the sc board is only 50,do you think i should look into that or do the unplug tests first?

Only thing that worries me is that in the googling i have done about plasma tv's that have a fault in one of the buffer boards is that the panel is bad and taking out the buffers,Do you think thats a possibility here with mine?

Thanks all i appreciate your time!

[tom66]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

I doubt it's the panel, you'd have no picture. I think the problem with trying with just one buffer is it will draw half the power, so might not shut off quick enough.

[tw2005]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

My theory behind the buffer board is if the set does not turn off purely on either then we should be able to assume the buffers are good and concentrate on either the PSU as you've suggested or the SC board.

I think the other thing here is what was said about the infomercials, mainly white.

The PSU,SC,SD & SU boards would be working hardest on a full white display. I know they state to set the TV to white for the adjustments.

Maybe it might be a good idea to go into the service menu and set the test pattern to white or maybe there is a white wash feature. It would be interesting to see how long the TV runs if at all under full load.

It may help speed up the fault finding. Certainly an intersting fault, so many variables.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Out of the half dozen times ive actually "seen'' it shut off ,It seems it can do 3 different things, 1 it can shut off pretty much all of a sudden, 2 the screen will start to get funky and dim then shut off,and 3 i saw its voltage start dropping ,the screen gets funky,but then pulls out of it and the voltage goes back to normal without shutting off.

But yeah it does seem to not like a lot off white,the voltage usually drops about .5v on bright scenes when its acting correctly.

The service manual does says to ''input'' a white scene when setting VSUS,dont know if there is a whitewash feature,I been trying to think of a dvd that would have a lot of white going on to watch to test with,but cant think of anything besides hooking up my laptop through svideo and putting a white background up.

If i was to get a new sc board,would it have to be calibrated with a Oscope?
Or would it be plug and play?

[tw2005]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Out of the half dozen times ive actually "seen'' it shut off ,It seems it can do 3 different things, 1 it can shut off pretty much all of a sudden, 2 the screen will start to get funky and dim then shut off,and 3 i saw its voltage start dropping ,the screen gets funky,but then pulls out of it and the voltage goes back to normal without shutting off.

But yeah it does seem to not like a lot off white,the voltage usually drops about .5v on bright scenes when its acting correctly.

The service manual does says to ''input'' a white scene when setting VSUS,dont know if there is a whitewash feature,I been trying to think of a dvd that would have a lot of white going on to watch to test with,but cant think of anything besides hooking up my laptop through svideo and putting a white background up.

If i was to get a new sc board,would it have to be calibrated with a Oscope?
Or would it be plug and play?

Unless it has been fiddled with you would not need a scope but in the manual it does tell you what adjustments need to be set if any depending what boards are replaced. Any voltages reglated by the SC board should be checked and I believe thats after the correct voltages supplied to it from the psu are set correctly first.
Section 10.3 in the manual.
SC Board adjustment after exchange Vad TPVAD (SC) -105V ± 1V VR6600 (SC).

When I did my SC on the Panasonic it was bang on, no adjustment but that was from Shopjimmy and out of a new TV with damaged screen so wouldhave been already adjusted for voltage.

It's a tough one to give good advice on. For all we know it may be the PSU or bad solder joints. It's strange how it drops but then somehow recovers itself.

[allsmith]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Unless it has been fiddled with you would not need a scope but in the manual it does tell you what adjustments need to be set if any depending what boards are replaced. Any voltages reglated by the SC board should be checked and I believe thats after the correct voltages supplied to it from the psu are set correctly first.
Section 10.3 in the manual.
SC Board adjustment after exchange Vad TPVAD (SC) -105V ± 1V VR6600 (SC).

When I did my SC on the Panasonic it was bang on, no adjustment but that was from Shopjimmy and out of a new TV with damaged screen so wouldhave been already adjusted for voltage.

It's a tough one to give good advice on. For all we know it may be the PSU or bad solder joints. It's strange how it drops but then somehow recovers itself.

If i order any boards they will be from shopjimmy.

I have not had any boards out of this tv yet,think i should pull the PSU and look for cold joints maybe?

[tw2005]

Re: Panasonic TH-42PX60U Plasma Turning Off Occasionally 7 Blinks

Try service mode, sect 9.3.1. I think in option,aging you can go full white,red,green, blue,black. You may be able to set the pattern to white in there. On mine in automatically changes through the different ones automatically every3 secs but I just tried it out quickly without my manual . Mine is a 2009 model.