Panasonic TC-P42S1 Plasma "A" board issue

[Dhamlin]

Hey guys, thanks in advance for your help!! I have gotten some great info and help from U guys!!

Ok, so, this tv has the 9 blinks error. " No communication between Sys MPU and Panel MPU"
Both these chips are located on the "a" board. Sys MPU is IC1100/ Panel MPU is IC9003. I am no electronics tech but I am super cheap and I deal with low voltage controls every day. I did some basic checking and I found that the STD_3.3VDC is comming from the "K" board (I think). The 3.3vdc is just fine comming in on the connector. When I check the 3.3vdc on the Panel MPU it comes on with startup but then goes off after error. That voltage comes on and goes to 2.49VDC before it shuts down. There is enough time for it to settle out before it shuts off.

I know from my own experience that devices shouldn't tolerate 10% higher or lower than design voltage. So, I was hoping to make a jumper to power up that chip in stead of finding the bad component in the switched circuit. I know this is not sound troubleshooting or repair. Was thinking of cutting the trace that supplies that area vith the 3.3vdc, make the jumper and see what happens....
Am I nuts? Worth a shot?
Better Ideas?
Its a very nice tv...They want $155 for a used "A" board on ebay....

[Dhamlin]

Re: Panasonic TC-P42S1 Plasma "A" board issue

Also wanted to say thanks to Tom66 for the schematics!!!!!

[tw2005]

Re: Panasonic TC-P42S1 Plasma "A" board issue

http://www.ebay.com/itm/151560282881...881%26_rdc%3D1

[Neelix]

Re: Panasonic TC-P42S1 Plasma "A" board issue

Had a quick peek at the service manual and STB_3.3V which supplies the Panel MPU actually comes from the DC-DC converter inside IC9004 and the converter is turned on or off by the System MPU. You should not jump parts because you can cause more damage that way. STB3.3V is dropping because STB_5V is dropping or because it's being pulled down or because the System MPU detected a error and then turned the converter off

[Dhamlin]

Re: Panasonic TC-P42S1 Plasma "A" board issue

well luckily my "better judgement" got thr best of me
I looked at both dc-dc converters and saw steady 5vdc comming in and 3.3vdc comming out(before power supply shut down. I am still hunting and pecking to find some kind of issue.
BTW, thanks for taking the time to look! I know it took me 15 min just to find the components I was looking for in there!!

[tw2005]

Re: Panasonic TC-P42S1 Plasma "A" board issue

A corrupt eeprom or flash IC can cause 1 blink so it's not necessarily going to be obvious what is causing it.

[Dhamlin]

Re: Panasonic TC-P42S1 Plasma "A" board issue

Thanks TW but its 9Blinks.
I am aware that there could be corrupt or damage IC's....I am really hoping to find a repairable component ...

[tw2005]

Re: Panasonic TC-P42S1 Plasma "A" board issue

Thanks TW but its 9Blinks.
I am aware that there could be corrupt or damage IC's....I am really hoping to find a repairable component ...

Ah, yes, I'm 8 blinks shy. I did manage to get a board to 9 once swapping that 48 pin flash ic and accidentally creating a short on one of the paths to that chip.

[Dhamlin]

Re: Panasonic TC-P42S1 Plasma "A" board issue

Yep I've done a couple of those. Almost feels like ur eyes are playin tricks on you when ur lookin at them later....Everything looks like a possible bridge