Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Smartjohn. Give it a shot if all else fails and you remove the shorts from the ic's. it sounds like your path is a different one since you have fets shorted. I can tell you thou that with sc2 removed pin 11 of dc regulator was outputting 9v. That's low but pin 12 put out 25v

Tw2005 thank you for the advise. Guess I got lucky. After all the tnpa4844 is unobtainable and if it failed I would prob need an a board as well but, hell it worked.

probably not a great idea unless you know there's no shorts. You had other issues as well I think?

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

You'd get absolutely nothing on the panel with a Vsus of 30V...

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Except.............. a little dust

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

The panel Vsus interestingly is determined by the gas pressure.
http://ars.els-cdn.com/content/image...06835-gr14.gif
(The image shows Vs as Ve and Vf as Vs.)

Low Vsus is possible with a mid-point gas pressure. The gradual increase in Vsus over the years may be a clue that manufacturers are increasing gas pressure in the panel. (They can't practically reduce it -- this increases the dielectric constant, reducing efficiency.) I guess as manufacturing techniques improve, higher pressures are possible. Additionally, it shows the reason why Vs and Ve are always different: it's pretty hard to get an accurate panel pressure each time when it's dependent over orders of magnitude of pressure.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

I may try that freakaftr8, but I am too much of a purist to give into this ugly beast that easy and possibly blow my SC board. As you said these baby’s are hard (near impossible) to find anywhere.

So I’ve been shooting pretty much by the hip until now. I found IC564 but that was only by chance. Now it’s time to laser target my methods and focus one what we know for sure: SOS7.

So from 2009 Tech Guide:
“Unplugging any of the connectors SC41/SU41, SU11/SD11, and SC42/SD42, opens the interlocked connection between VF_GND and CHA on the SC board. This floats point “CHA” and Q16471 turns on. IC16561 outputs a high to pin 21 of connector SC20 triggering shutdown"

Also,

“The floating ground circuit monitors the scan circuit output, the 15V_F, the scan_pro, Vscan, and the physical connection between the SC board and the SU/SD board (CHA). If any abnormality occurs on any of these lines or Vsus is missing, the TV shuts down and the power LED blinks 7 times"

So, this circuit is Really the source signal for SOS7. It reads right to left, with MAIN_STOP_0 being the output that traces up to IC561. Anything that’s defective along the path, OR if one of the required inputs is not showing up, then SOS7 (7 blinks will happen) I know VSUS is working, but I can’t read where it’s detected clearly yet from this logic. I see inputs for scan_pro, 15V_F, CHA but still trying to sort out the others. Food for thought…..My scope is warming up and I plan to hang some test leads around this ckt to see what happens at power up.... By the way, all my FETs tested OK.

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Hey all sorry for the delay. Vsus and all other voltages are within 2 v of specified voltage. Oddly enough the set has been running strong and hard. For three days flawlessly and I have been monitoring
Voltages from time to time with no change. I have done some more "probing" of semis on the board especially in the failure prone areas smartjohn has issues with and all seem to be in spec from what I can tell.. Who knows why but with pin 21 disconnected and still getting a high on the pin its still running.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Hey all sorry for the delay. Vsus and all other voltages are within 2 v of specified voltage. Oddly enough the set has been running strong and hard. For three days flawlessly and I have been monitoring
Voltages from time to time with no change. I have done some more "probing" of semis on the board especially in the failure prone areas smartjohn has issues with and all seem to be in spec from what I can tell.. Who knows why but with pin 21 disconnected and still getting a high on the pin its still running.

So VAD and Vscn are on target? One could only assume the detection circuit is faulty.

I assume you mean pin 21 is isolated from the A board but is still a high at the SC side of things.

Would'nt it be ironic if the majority of of boards failed had been tossed purely on a false detection but operationallly ok.

My only concern would be when you have a genuine fault or short and no shutdown on SOS7 is that going to present a fire risk.

That would be tragic.

maybe a bad zener? 5.1,15,36V

Q876 I suspect will have marking C3 W, 2PD601ART

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

So VAD and Vscn are on target? One could only assume the detection circuit is faulty.

I assume you mean pin 21 is isolated from the A board but is still a high at the SC side of things.

Would'nt it be ironic if the majority of of boards failed had been tossed purely on a false detection but operationallly ok.

My only concern would be when you have a genuine fault or short and no shutdown on SOS7 is that going to present a fire risk.

That would be tragic.

Yes that is a possibility. But a while ago I got a panny th-50pz85u going that was having an SOS shutdown for panel failure. Don't quite remember the code. But after extensive research and board swapping between like sets it appears the only last resort was to clip the SOS pin going to c1 c2 c3 and it powered up with a faint vertical bar to the left. Faintly blue in color. Comes and goes. It's a fault in a cof film ic. Unrepairable. But it now works and beautiful picture.

Back to this tv. Yes The sc board is outputting a high but isolated that circuit from the a board. If there comes a short it will damage the ps most likely.

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Actually I take that back. Vad is 5v low

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Actually I take that back. Vad is 5v low

5V low with respect to 175V or below the lower threshold where SOS7 triggers?

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Ok sorry again. I was misreading a value. Vad is supposed to be 175v I have 174.2v. My dvm batteries were low.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Ok sorry again. I was misreading a value. Vad is supposed to be 175v I have 174.2v. My dvm batteries were low.

For me the important thing is to establish that all the voltages produced by the SC are good.

So it sounds like they are which surely could only mean false detect. It'd be really interesting to locate the issue, may help others but i could understand if you just packed it up and used as is.

just as interesting when I dicovered the onboard LED open cct on one of mine which triggered SOS6 but perfect board otherwise. Replaced the LED and it's been running sweet about 7-8 months now.

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Finally success! Sorry freakaftr8, it looks like my cruise has ended.. After I zeroed in on the circuit in post #65, I decided to re-check IC724 / IC725 (right next to SC42 connector). IC724 was only giving me 48 ohms from pin 2 (common) to pin 1 (output). I remember getting this before (#13) but passed it off because during the current test (#26 & #29) neither of these got very warm. I already had these L78L05A 5v regulators so I just decided to replace them. Sure enough, when I checked IC724 out of circuit, 1 to 2 was still 48 Ohms. Checking the new ones in circuit, I was getting between 2K to 4.8K depending on polarity and after the caps settled. Remember, anything bad in the circuit in #65 will possibly result in SOS7.

So I fired the set up in isolation mode (no SU/SD connected, SC50 jumpered) and Bingo, the fans came on, no relay cut out!! Then shut it off in less than 15 seconds. I had checked my old SU / SD boards. Pin 2 on the old SU board was 20 ohms to the ground plate. New board measured over 5Meg ohms. So I popped in both new buffer boards. Bingo it fired up and I got the setup menu! I had to reseat all the SU / SD board ribbon cables as I was getting some blank spots on the horizontal trace. Didn’t really need the scope but it looks cool in the picture anyway! Ha ha..

So just to summarize my repair:

SC board: IC564, IC724, IC725 (but was probably ok)

New SU board

If anybody else has some dead TNPA4844 SC boards, PM me and I may be up for buying a few.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Nice one. Nice cheap repair too! I think the more people that have a go at this level the better. Could help out quite a few.

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

You guys are tempting me into repairing one of these. Damn good TVs.

[tw2005]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

You guys are tempting me into repairing one of these. Damn good TVs.

There's nothing like the thrill of component level. Very satisfying. I honesty rated my chances as marginal, but having a go and winning, makes you want more of these to fix.

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Alright smartjohn! Way to go! So to recap, to think a failed upper buffer caused this board to short out the ic724/25?

[tom66]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

For anyone interested:
http://www.ebay.co.uk/itm/Panasonic-...item3cd022b99a

[smartjohn]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Alright smartjohn! Way to go! So to recap, to think a failed upper buffer caused this board to short out the ic724/25?

I would say that was the original failure. As to what killed ic724, it may have been my hair brained assumption in #1 - #3 where I replaced the IGBT with an NPN bipolar... The Lord was looking out for me there, and I didn't blow more junk in the process! It's possible that the regulator blew earlier. Not sure what blew the inverter IC564 but it had a Vcc to GND dead short.

Anyhow, I give all the credit to Someone greater than me!! I need to sell this one as I am currently looking for work (who else has 40+hrs to fix something like this!) I plan to eventually fix and donate most of them to others in more need. Hey freakaftr8, PM me with your address. If your IC724/725 is bad I can help you out. I ordered 32 of them by mistake, but it was only 4 bucks total!! too funny...good luck to all...

PS: Tom66 wonder what the VAT (ok I checked, 19%) on 1 Euro and shipping would be to US?

[freakaftr8]

Re: Panasonic TC-P42G10 Plasma - Seven red blinks Dead No power

Thats very kind of you and also to donate some TV's as well. I pick up TV's broken and some I sell and some I donate as well. As to the regulators I might take you up on That but I have some dead panasonic ysus boards with a bunch of failed fets that I would have rebuilt but it was cheaper just to buy a working board and have a bunch of these regulators already. A bunch of my sets end up in group homes and the such.