Panasonic TC-P50U50 Powers Off - 8 blinks

[nomoresonys]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

Seems to be a tough little problem, maybe send it to one of those trusted fixers on ebay.

[nomoresonys]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

One there but they may be thinking it's the same usual 4 part repair, if I were going to let them try to fix it, I would contact them and tell them I already tried replacing those 4 parts and see what they have to say: https://www.ebay.com/sch/i.html?_fro...acat=0&_sop=15

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

Check for continuity
between pins 1 and 2 of connectors
SS52 ~SS57on the SS board. Do not
plug in the TV.

Yup, already did that as part of Panasonic's troubleshooting guide. Does not appear to be any issues as I got the following values (roughly):

SS57 - 1.3 ohm
SS54 - 1.7 ohm
SS55 - 1.4 ohm
SS57 - 1.8 ohm

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

If continuity is ok in all the connectors, problem is prolly in the ss board, if thats ok could be panel problem. Where did you get the replacement parts?

Aliexpress. Only note is that the only part I did NOT replace were the 2x 5.6 ohm resistors because I tested them and they were fine. Did not want to replace these because of how difficult it would be to solder them.

I guess my last resort if we can't try anything else would be to replace these, but I can't imagine them to be a problem if they test properly.

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

One there but they may be thinking it's the same usual 4 part repair, if I were going to let them try to fix it, I would contact them and tell them I already tried replacing those 4 parts and see what they have to say: https://www.ebay.com/sch/i.html?_fro...acat=0&_sop=15

Thanks for that suggestion. For $70, it's probably not worth it on this Tv at that point and I'd probably give away the TV to let someone else try. Was hoping to be able to get this unit working from a hobbyist perspective. Hate seeing stuff go to waste!

[nomoresonys]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

I hear you, I don't think I would either, the test in post #16 with tv staying on narrows the problem to SS board or panel, I am not sure how to determine which one, maybe another member knows if it's possible.

[nicholas1110]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

It is very important to replace those 5.6ohm resistors. If the transistor was shorted the resistors were damaged even if they read close to the correct resistance. I have seen many of them black and burnt and still read correct resistance.

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

It is very important to replace those 5.6ohm resistors. If the transistor was shorted the resistors were damaged even if they read close to the correct resistance. I have seen many of them black and burnt and still read correct resistance.

Dang ok, I'll go replace them later and report back. They're surrounded by other stuff and looks like a pain in the butt to get off!

[Biruslapio]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

Resistors either resist or resist a lot(open circuit after failure).

The thing to do is desolder ALL the big transistors and diodes related to power and switching for the plasma panel, measure them off circuit and check for a partially bad one, that is leaking current in reverse polarization or even has too low forward resistance.

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

Resistors either resist or resist a lot(open circuit after failure).

The thing to do is desolder ALL the big transistors and diodes related to power and switching for the plasma panel, measure them off circuit and check for a partially bad one, that is leaking current in reverse polarization or even has too low forward resistance.

That's a good point. However in my case I'd probably like to avoid doing so. I can feel the traces buggering up on the transistors/diodes that I replaced. So I'd like to really avoid any more stresses to the circuit board if I don't have to!

[Biruslapio]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

The replacement you did was not necessary since that is for when the DG302 blows up and burn the resistor + their gate driver and the RF diode next to it.

There may be fake DG302 in the market as for every common IGBT used in plasmas (most famous fake parts are toshiba, fairchild and renesas).

I circled on the SS board image points of interest, all the important diodes and transistors, plus TPVe testpoint (voltage generated by SS board), it must match the service manual specified voltage, and those capacitors + the big inductor can develop bad soldering joints as aging occours.

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

The replacement you did was not necessary since that is for when the DG302 blows up and burn the resistor + their gate driver and the RF diode next to it.

There may be fake DG302 in the market as for every common IGBT used in plasmas (most famous fake parts are toshiba, fairchild and renesas).

I circled on the SS board image points of interest, all the important diodes and transistors, plus TPVe testpoint (voltage generated by SS board), it must match the service manual specified voltage, and those capacitors + the big inductor can develop bad soldering joints as aging occours.

I have replacement 5.6 ohm SMD resistors (R041 and R051), but then I just noticed the ones I bought are physically too small! I could probably be creative in using a blob of solder to jumper it together. A little tough getting the right size because I got these off Aliexpress and seemingly none of the sellers list out the dimensions!

In the meantime, I powered on the TV with SS33 disconnected and TPVe tested 170V as per the service manual. Those other transistors I tested in-situ and they don't seem to have any abnormal shorts. I also attempted to do the typical gate/drain/source test using the diode function but it doesn't seem to work on ANY of them. I'm guessing it may be the way it's mounted to the board and/or being interfered with other components? Not sure if I'm doing something wrong but it's fishy that I was not able to test ANY of them properly. I've done the transistor test a dozen times before and I also made sure to look at the pinout from the appropriate datasheets.

[nobbnobb1]

Re: Panasonic TC-P50U50 Powers Off - 8 blinks

Just replaced the 5.6 ohm resistors. No luck, still the same problem. Pretty darn close to just giving up on this SS board now.