Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

[jhbox]

Got the TV from a friend, 14 blinks normally, 8 with the SN board unplugged at SN2/P2.

I've done a good bit of research on here and have determined that the SN board has a short somewhere, but am unsure exactly what. I have checked the ICs, all of which seem to check out when I test resistance to TPVFG.

What is the most common component on these SN boards to go bad? I'm pretty good with soldering, most of my experience is actually with control units from old motorcycles but it translates well.

Any help is greatly appreciated.

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

I just realized that I am also showing resistance/continuity between the Vsus at SS11/P11.

[tw2005]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

start with surface transistors 30f131, don't why you are testing ic relative to floating ground, resistance across sn2 also a good place to check

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

I tested the ICs as it was a suggestion by a user here: https://www.badcaps.net/forum/showth...old#post626878
Also I didn't test against ground, it was the test point at TPVFG, pardon me.

Now just to verify, to test my transistors I will :
-check resistance between the emitter/gate, ensuring continuity only one way
-check resistance between the collector/gate, ensuring continuity only one way
-check resistance between the emitter/collector, ensuring no continuity either way

[tw2005]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

I tested the ICs as it was a suggestion by a user here: https://www.badcaps.net/forum/showth...old#post626878
Also I didn't test against ground, it was the test point at TPVFG, pardon me.

Now just to verify, to test my transistors I will :
-check resistance between the emitter/gate, ensuring continuity only one way
-check resistance between the collector/gate, ensuring continuity only one way
-check resistance between the emitter/collector, ensuring no continuity either way

Ah ok. Understand know buffer ic yes floating ground and output. Yeah justprobe across the transistors legs and tab. They would norHi Gary. Would the tv still be available and could I collect it later today? I'm at enogerra not sure what time I finish this afternoon. Cheersmally fail dead short. I think there's 2 pair of 30f131 that go on a sn

[tvtimmy]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Are you having auto-correct problems Tw?

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

not sure what you are trying to say there tw2005... thanks I guess?

[tvtimmy]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

If your meter has the continuity beep feature, use it. Test the all the 3 legged parts for shorts. Now some the parts that have the letter D in front of the number will read short untill you lift the legs off the board. Then the diodes will read ok. Also checking parts in diode mode can prove helpfull.

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

So I just tested all of the 30f131 transistors, 4 of the 6 had continuity between all legs and two had continuity with high resistance (not enough for my multimeter to berp). Which of these are good?

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

I'm not sure I'm doing this right, please forgive my noobishness. I have the pinout here: http://www.datasheetcafe.com/30f131-datasheet-pdf/

1 gate
2 collector
3 emitter

Now correct me if I'm wrong for an operational pnp transistor
Pos-gate neg-emitter = no continuity
Pos-gate neg-collector =no comtinuity
Pos-emitter neg-gate = continuity
Pos-collector neg-gate = continuity
Pos-emitter neg-collector = no continuity
Pos-collector neg-emitter = no continuity

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Wait, do I need to remove these from the board to test them? Because 4 of the 6 are getting continuity across all three legs and that seems odd

[tvtimmy]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

The row you are checking has 4 30f131s and two diodes in between. Diodes will read good when you remove the 4 bad 30f131s.

[tw2005]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Wait, do I need to remove these from the board to test them? Because 4 of the 6 are getting continuity across all three legs and that seems odd

Congrats you found them

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Congrats you found them

Well I guess I'll start by replacing those 4.

[tw2005]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Watch out for fake 30f131. They're out of production as are most of these parts.

[jhbox]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

I finally got this done (I accidentally knocked a resistor off and had to wait for replacements to arrive), and now am receiving 8 blinks. See the attached error.

Looking at the SS board, there looks to be some arc marks on one of the grounds, are there any common failure point on these SS boards?

[freakaftr8]

Re: Panasonic P42S30 14 Blinks, need help diagnosing SN board issue

Yes. Along with more shorted mosfets if you have arc traces on screw lugs. Every time I repair a Panasonic a usually take the boards off in reflow clean solder underneath the lug connections and screw down the boards tight