TH-P50G15A - 6 Blinks- Bad TNPA4782

[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

[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?

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

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

[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.

[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

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

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

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.

[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

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

Forgot to mention I also replaced IC773, 464, and 465 to be safe. For D806 i have 0.758 and OL in diode mode, 9.75k resistance in both directions

interesting, I may have an issue there. i get the resistance but in diode 1.69 and 1.67. Do you remember waht yours was reading before you replaced it?

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Forgot to mention I also replaced IC773, 464, and 465 to be safe. For D806 i have 0.758 and OL in diode mode, 9.75k resistance in both directions

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

With that zener D608 what do you get in diode mode both directions and what resistance both directions?

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Pins 3-5 resistance on any of these IC773,464,465. What resistance do you have?

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Q701,702,818 no shorts but I'm replacing .

I'm getting similar on those resistors. I may remove from cct and check since 1 is burnt at the solder.

Well with mine at this stage I'm thinking

Q601,661,441,451, 701,702,818,551
D618,
IC771,773,464,465(all of the Vcc lines are tied so I do not trust these inverters)
IC521

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

my Q451 measures 0.674 and OL on G-E on diode mode. both my R869 and R613 slowly raises in resistance until around 42.8k ohms.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

So far I also replaced Q818 2sk3018 and only IC771 78L05, IC724 and IC725 seem good. I checked about every large smd diode I can find and nothing seem shorted. Q441 was 45G127 (the one on the right heatsink). that one didn't have a diode in front of it. measuring the TO-220 diodes I'm getting 0.287 and OL.

yep got mixed up with other 45g127, both mine are dead

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Ok, well i'm only just starting on this but is your Q451 shorted G-E ? I'm finding you have to be 100% thorough nearly skipped over that one.

For transistors so far, Q661,601,441,451,D618,

Also, can you look at R869, R613 47K near D618. 613 is burnt and I can't get a stable reading suggesting these may have an issue but have not looked at the schematic yet

[Glitcher]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

So far I also replaced Q818 2sk3018 and only IC771 78L05, IC724 and IC725 seem good. I checked about every large smd diode I can find and nothing seem shorted. Q441 was 45G127 (the one on the right heatsink). that one didn't have a diode in front of it. measuring the TO-220 diodes I'm getting 0.287 and OL.

[tw2005]

Re: TH-P50G15A - 6 Blinks- Bad TNPA4782

Have you rechecked the buffers yet? I'd check Vfo at the connector to Vfg resistance