TH-P50G15A - 6 Blinks- Bad TNPA4782

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

I thought I also had this but nope. Found two resistors R521 and R522 open circuit near IC521. I initially had IC521 shorted which was replaced. replaced the resistors but still getting a short flash and then 6 blinks.

yep, these look toast to me. can't see mark and looks open

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Ok, the jury has come back with not guilty. Just fixed my second 4782 first go.

Here's my list, some of which again maybe overkill but I'm sticking to this until i know more.

Q601, RJK6026 shorted_ used STP10NK60ZFP 600V 10A N FET
Q661, RJP6065, shorted_ used RJP63F3A
Q441, 45G127 _ shorted_used 45G128
Q451, 45G127 _ shorted_used 45G128
Q701, MMBTA92
Q702, 2PD601
Q818, 2SK3018 _ used 2N7002
Q551 CPH5524_ shorted
D608, MA8120M, MAZ81200ML 12V 150mW zener(DIODE ZENER 12V 150MW SMINI2) _ open cct_ I had to improvise here and used 1N4742 12V 1W axial lead
D618 RF101L4S 400V 1A shorted
R613 47K was open cct, can not tell in cct if good

IC771,724,725 78L05 _ seemed ok

IC773(bad),564, 464,465 _ TC7SH14F

IC521 M81707FP _ used M81737FP

R521,522 100ohm 5% metal _ burnt out open cct

NOTE: These are AA_CSL, AA_CML & they originate from IC562. If those resistors are blown then that high voltage has been feed back to the octal buffer ICs at SC20.
Both mine IC561,562 were shot showing a P5V in resistance of about 500ohms

Once removed that cleared. IC563 is also on the same Vcc but seems to have survived.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

There is one glitch I've found and not sure what to think or whether it's a characteristic or not.

When in serv tool, if you hold return it will shutdown and reboot the TV. With the original board i fixed with no vset cct it does this.

with this board which has vset, it 7 blinks. turn it off/on and back to normal. Can be repeated so unsure if there's some tiny part I've missed or what.

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Maybe worth trying on some test patterns - could be some patterns such as full white or all black will trigger a shutdown.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Maybe worth trying on some test patterns - could be some patterns such as full white or all black will trigger a shutdown.

Ran full white for half an hour, certainly heats that SC up. No, I was thinking there's some residual voltage as when you force it to recycle it tries to fire the panel up pretty quick.

with the remote you can't forec it to recycle immediately, there's a period where the main board will not recognise the on command, like a lock out until it's ready or a set period.

Not overly concerned but i hate the unexplained. never seen a 7 blink using return to cycle on any Panasonic before so would not surprise me something minor is wrong with the detect cct.

[tom66]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Try setting it to dynamic pic mode and try turning it to all black then after 5mins press MENU or something to light up the screen does that trigger an error?

A lot of these older Pannys will essentially turn the panel off on all black, the panel still is primed but the priming is reduced to the minimum level and sustaining is eliminated for all but the first subfield. Lets them claim 5,000,000:1 dynamic contrast. As soon as an image needs to be displayed, priming glow will return almost immediately.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Try setting it to dynamic pic mode and try turning it to all black then after 5mins press MENU or something to light up the screen does that trigger an error?

A lot of these older Pannys will essentially turn the panel off on all black, the panel still is primed but the priming is reduced to the minimum level and sustaining is eliminated for all but the first subfield. Lets them claim 5,000,000:1 dynamic contrast. As soon as an image needs to be displayed, priming glow will return almost immediately.

Out of time I'm afraid. Heading home TV remains. Not bad though, fixed 50u20(card swap A board), 50St30A 7 transistors, P50G15 including two 4782 SC rebuilds.

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

How did you figure out if IC563 was good or bad? Where is the P5V.

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Well just tried replacing IC561,562, and 563 and still no avail. What measurement did you get on diode mode for D608?

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

How did you figure out if IC563 was good or bad? Where is the P5V.

Well I've seen something similar on the one and only 5081 board which also had burnt out 100 ohm resistors on those lines to IC521.
It stands to reason that those resistors can't burn out fromthe buffer IC only from high voltage from the FET driver. They're on the input side so internally that chip would have to short internally for this to happen.

Just ohm out pins 10-20 on those or 7-14 on that inverter IC. that's on the P5v or 5V that enters from the A board at SC20

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Well just tried replacing IC561,562, and 563 and still no avail. What measurement did you get on diode mode for D608?

answered in post #40 but now with this huge 1watt zener 0.663 & 1.7.

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Hmm well they ohm out fine now that I replaced them. I was wondering what measurements do you get from Q604? the SMD mosfet next to D806, im having some suspicion on that one.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Hmm well they ohm out fine now that I replaced them. I was wondering what measurements do you get from Q604? the SMD mosfet next to D806, im having some suspicion on that one.

blk lead on D, I get is 9.36k G-S, ol on any other
red lead on D, 2.26Meg D-G, 2.31Meg D-S

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

did you isolate r613 to confirm? also watch out for burn out tracks could be open ccts

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Looks like I found the problem, I desoldered it and I'm not getting any readings at all from it seems like it blew. It seems to be a P-Channel 250V 3A Mosfet vg = 30v. Now If I could find a suitable replacement from some of my salvaged Panasonic boards.

I isolated both R613 and R869 and they measured good.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Looks like I found the problem, I desoldered it and I'm not getting any readings at all from it seems like it blew. It seems to be a P-Channel 250V 3A Mosfet vg = 30v. Now If I could find a suitable replacement from some of my salvaged Panasonic boards.

I isolated both R613 and R869 and they measured good.

so what are you saying , you can't replicate in cct my readings in diode mode?

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Yep, I was also getting OL in cct. This would explain the different readings I got for D806 which is connected to the gate and source of that FET.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

have you looked at the pictures I posted of that part of the cct being deleted? I have two AF boards , one with, one without that Vset cct, so clearly it's possible for it to be removed and the Tv to work.

I suppose I could remove mine and check that P fet. i always thought they'd blow short and FETs need to be switched on to check. I think very early on I did not know this and had a FEt show open but I was testing wrong. Don't kow much about P fets but that one is unique, I tried looking for a sub a while back for a post and never had any luck. Also unique I think for these models.

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Did you remove both of those ICs to get the tv to work?

My D806 was completely blown in half so I had some suspicion the damage could go to that FET. I could be wrong though. I have seen and had some FETs that have completely blown which went open cct but the damage is usually obvious.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Did you remove both of those ICs to get the tv to work?

My D806 was completely blown in half so I had some suspicion the damage could go to that FET. I could be wrong though. I have seen and had some FETs that have completely blown which went open cct but the damage is usually obvious.

No, that's how that board is from manufacture which is my point. panasonic decided to delete it somewhere along the line. None of the photos at SJ show it deleted but i have one and if you go through Hombre's post he has a 46" board also with no vset cct.

I have 2 rev AF but hey are not the same. I don't have the other board in front of me just the one with the same setup as yours.

I'll remove my FEt and see what it does out

Any chance we can start referring to D806 as d608, i keep looking for a diode that does not exist