Panasonic TH-42PZ800 8-blink error mystery

[nervx]

Years ago my tv gave a 7 blink code which turned into 8 during diagnosis. I had ordered a replacement ss board but somehow the tv started working again and i never used the board. Now a week ago my tv flickered and shut off at random and gave the 8 blink error code. The same issue it had all those years ago. The only difference this time is that over the last few months there has been some purple and green tinge that comes and goes in more solid colors such as white.

Anyway i checked all the screws and replaced the ss board with a known good one and still got 8 blinks. I saw a post where people were discussing the purple/green color issue which usually comes with a 7 blink error. So i pulled the sc/su/sd boards. The little ones look fine. The SC there's some brown spots and one mounting screw the metal is sort of chipped a bit but im not sure if this would cause such an issue. After cleaning and putting the tv together i ended up with the same 8 blink error. Tried turning the tv on a few more times with the same result and then one last time and its been on for 3 hours running fine. The purple and green tinge hasn't shown up yet either.

I attached pictures to give an idea of what im seeing and what the sc board looks like. Who knows if it will stay working tomorrow but any idea what could be causing the problem? And a side question, when replacing the ss board you shouldn't have to touch the pot adjustment correct?

Any help is greatly appreciated.

What the flicker looks like
https://youtu.be/_i4_IYRCfvc

[anmol]

Re: Panasonic TH-42PZ800 8-blink error mystery

Years ago my tv gave a 7 blink code which turned into 8 during diagnosis. I had ordered a replacement ss board but somehow the tv started working again and i never used the board. Now a week ago my tv flickered and shut off at random and gave the 8 blink error code. The same issue it had all those years ago. The only difference this time is that over the last few months there has been some purple and green tinge that comes and goes in more solid colors such as white.

Anyway i checked all the screws and replaced the ss board with a known good one and still got 8 blinks. I saw a post where people were discussing the purple/green color issue which usually comes with a 7 blink error. So i pulled the sc/su/sd boards. The little ones look fine. The SC there's some brown spots and one mounting screw the metal is sort of chipped a bit but im not sure if this would cause such an issue. After cleaning and putting the tv together i ended up with the same 8 blink error. Tried turning the tv on a few more times with the same result and then one last time and its been on for 3 hours running fine. The purple and green tinge hasn't shown up yet either.

I attached pictures to give an idea of what im seeing and what the sc board looks like. Who knows if it will stay working tomorrow but any idea what could be causing the problem? And a side question, when replacing the ss board you shouldn't have to touch the pot adjustment correct?

Any help is greatly appreciated.

What the flicker looks like
https://youtu.be/_i4_IYRCfvc

check page 13

[nervx]

Re: Panasonic TH-42PZ800 8-blink error mystery

Thanks but that manual doesn't really give me any information that i didn't already know.

[nervx]

Re: Panasonic TH-42PZ800 8-blink error mystery

Sadly I've been unable to solve the 8 blink issue but i did notice something odd.

If the tv is acting up it usually wont stay on very long.
If I unplug the ss33 connector on the ss board as per service manual, it will power on and stay on but with no display as expected.
If i let it run like that for a few minutes then shut down to reconnect the ss33 connector the tv works fine the next time it's powered on for a random amount of time. Usually a few hours.

I get the same result with original and replacement ss boards.

This little trick isn't a feasible solution so does anyone have any clue what might be going on?

[nomoresonys]

Re: Panasonic TH-42PZ800 8-blink error mystery

not sure but with any tv that old, the first thing I suspect is capacitors.

[R_J]

Re: Panasonic TH-42PZ800 8-blink error mystery

Have you checked the connections on the C2 board, plug C21 and C23? The problem may be on the D board, ic9003 monitors the SOS8_SS line and there are a few components on that line, D9028, R9159 and C9157. maybe try some freeze spray on those components? It may be the detection line that is causing a false trigger.

[nervx]

Re: Panasonic TH-42PZ800 8-blink error mystery

not sure but with any tv that old, the first thing I suspect is capacitors.

That and burn marks were the first thing i checked. I've pulled every board but the c1/c2 boards to check for damage and reseat cables but no luck. The SS board was also replaced.

Have you checked the connections on the C2 board, plug C21 and C23? The problem may be on the D board, ic9003 monitors the SOS8_SS line and there are a few components on that line, D9028, R9159 and C9157. maybe try some freeze spray on those components? It may be the detection line that is causing a false trigger.

The c1/c2 boards were the only ones i didn't remove due to all the panel heatsinks and stuff attached to them. Visually they show no signs of damage. Pretty much everything in the tv has been thoroughly cleaned.

D board looked good showing zero signs of damage.

C23 has been played with a fair bit and disconnected on both ends while changing boards. I could take another peak at it but its a pretty simple connector and seems fine.

C21 i unplugged from the d board side when inspecting that board. I did not disconnect from other side due to restricted access. I will have to check this as i noticed the 3 flex cables from the d board to c boards do bulge a bit so maybe the connection is slightly loose.