Panasonic TH-42PZ77U SC board repair 7 blinks

[johnboy1313]

Using the thread below and the attached .pdf for troubleshooting 7 blinks, I've determined that it appears that I need to either repair or replace my SC board. I would like to try to repair this board if possible.

https://www.badcaps.net/forum/showthread.php?t=21700

With everything connected, the screen flashes briefly at startup and then the LED blinks 7 times. With the SU and SD disconnected, the LED blinks 6 times once, then 7 times over and over. With the SU connected and the SD disconnected, the top of the screen flashes and the LED blinks 6 times once, then 7 times over and over. With the SD connected and the SU disconnected, the bottom of the screen flashes and the LED blinks 6 times once, then 7 times over and over. With SC2 and SC20 disconnected the unit powers on and off with the remote. According to the attached .pdf file, this means the SC board is at fault.

What do I do now?

[DavidOH]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

I would say unless you can find an obvious problem on the board your looking at replacing it. After a quick search it looks like about $100. I did see one on sale for $65.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

I see repair services being offered on eBay. I figured I would check here and see if anyone knew anything about it.

[drpj23]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Is there a short between the two prongs on the SC board?

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

7 blinks is caused, sometimes, by chassis detect failure. Is there a connector SC50 on the SC anywhere? If so, connect the two pins. This should disable the chassis detect and run the PDP.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

7 blinks is caused, sometimes, by chassis detect failure. Is there a connector SC50 on the SC anywhere? If so, connect the two pins. This should disable the chassis detect and run the PDP.

I'll get back to you tonight.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

I searched the board and don't see an SC50 connector.

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

How about a picture?

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yeah, after all this time, you'd think I woulda snapped a picture by now. I'll get one this afternoon.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

This will have to do until I can get home.

http://www.shopjimmy.com/panasonic-t...u-sc-board.htm

[rayrod81]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

The common failure on this board is one or more of the FETs in one of the two long rows of FETs. I will have to look up the part number. Keep in mind that after you do the repair there is a firmware upgrade that needs to be applied to keep this problem from recurring.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Firmware, ugh!! I have no idea about upgrading the firmware on these sets. The only one I ever did was on a Samsung with a USB port, super easy. I don't suppose this is as easy, or is it the kind where you have to have a jig?

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

On Pannys, it is usually possible via the SD card slot.
I forgot I have repaired the TH-42PZ70BA which had a shorted fet on the SC. I never applied the firmware update though...

[rayrod81]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

The part number is B1DFKM000002 or 5N2307. Here is thread from AVS Forum with some info for you. http://www.avsforum.com/t/1001318/ma...#post_17876879

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Yes, mine was the same fet.

I miss this very over-engineered chassis. The newer ones aren't as nice.

And on mine, the left hand one was also bad like on the AVS Forum thread. Wonder if it's just a coincidence or if that one fails the most. If the gate drive is closest to that one (I believe the gate drives are all common), it will turn on first slightly, so briefly have to take all the load, leading to higher power dissipation.

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

BTW, you can briefly run the TV with that fet disconnected, just cut both of the visible leads. There are 6 in parallel so running with 5 briefly is OK. You need to replace the part, but it will verify if there are any other problems with the rest of the TV.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

BTW, you can briefly run the TV with that fet disconnected, just cut both of the visible leads. There are 6 in parallel so running with 5 briefly is OK. You need to replace the part, but it will verify if there are any other problems with the rest of the TV.

Great, thank you guys. I'll report back.

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

The part number is B1DFKM000002 or 5N2307. Here is thread from AVS Forum with some info for you. http://www.avsforum.com/t/1001318/ma...#post_17876879

rayrod, thanks for that link. In the post the OP mentions pulling a leg of each transistor to detect a short. I've never actully used the diode test on my meter. What exactly am I looking for when testing a transistor for a short?

[tom66]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Zero or very close to zero (<20)

[johnboy1313]

Re: Panasonic TH-42PZ77U SC board repair 7 blinks

Following the directions on the link provided by rayrod, I pulled one leg of each transistor in the first group. I didn't find any shorts, but I did find evidence that something might not be right. I apologize for the following. My kids are using the computer and for some reason I can only attach one pic to a reply at a time

With the DMM set to diode, I put the red on the lifted leg and the black on the other leg. If I switched it, I got an open circuit. Testing all seven (all of which are the same part number) like this I got
1 = 1427
2 = 1427
3 = 640
4 = 1427
5 = 1427
6 = open
7 = open