Panasonic TH-50PX80U SC board troubleshooting

[braxton]

Hi I have this Panasonic plasma TV that appears to have a bad SC board based on my troubleshooting (7 blinks). As it is an old TV, I was hoping I could repair the board (as opposed to trying to replace it and hope for the best).

Can anyone point me in the right direction as to which part(s) commonly fails on this particular board? The board is a TNPA4393.

Thanks for any insight...

[ReeceyBurger123]

Re: Panasonic TH-50PX80U SC board troubleshooting

Do you know how to check for S/C ?

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

Do you know how to check for S/C ?

Sorry I don't know what s/c is (unless you mean SC??
I have a digital multimeter and am OK with soldering but am not an electronic tech.

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

Do you know how to check for S/C ?

If you are referring to the SC board, I can give you what I have tried. First I picked up the set with 7 blinking lights and know nothing else about the history of the set. First, I removed the cables to the SU and SD boards and still had 7 flashing lights. Next I removed the cables from SC2 and SC20 connectors on the SC board and then the red light stayed solid -no more blinking (still blank screen). This would seem to suggest the SC board to me.

[tech2014]

Re: Panasonic TH-50PX80U SC board troubleshooting

S/C means short circuit

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

S/C means short circuit

Yes I can check for short circuit with my multimeter. So far I know that the 2 pins on SC2 are not shorted. What are other obvious short locations?

[Alastair E]

Re: Panasonic TH-50PX80U SC board troubleshooting

PX80 SC boards are extremely reliable.
As such, they tend to be very cheap--and as they are fairly old--Plentiful.

Might as well just buy another...

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

PX80 SC boards are extremely reliable.
As such, they tend to be very cheap--and as they are fairly old--Plentiful.

Might as well just buy another...

OK thanks for the input. Based on my troubleshooting described above, is the likely culprit an SC board or could it be something else - like the A board? Your reliability comment has me worried now.

I just hate to be throwing money into an old 720p tv- I would prefer to fix for under $20 if possible

[Alastair E]

Re: Panasonic TH-50PX80U SC board troubleshooting

fully disconnect and remove the buffers. you must remove all the large screws to the sc from buffers--best take 'em completely out of set.

with everything else connected, fire it up.

If it runs with no blink--the buffers are faulty.

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

fully disconnect and remove the buffers. you must remove all the large screws to the sc from buffers--best take 'em completely out of set.

with everything else connected, fire it up.

If it runs with no blink--the buffers are faulty.

With SU and SD removed I get 7 blinks

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

I know there is a common transistor/mosfet repair for the TH-42PZ77U SC board so I was hoping there was a common check and repair for the SC board from the TH-50PX80U series as well

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

PX80 SC boards are extremely reliable.
As such, they tend to be very cheap--and as they are fairly old--Plentiful.

Might as well just buy another...

I see shop jimmy has the SC board but I'm looking at >$80 Canadian which is more than I'd like to spend, especially since it might not fix the problem.

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

I found a guy locally that had a compatible used SC board but it displays exactly the same symptoms (7 blinks with buffer boards disconnected, solid red with SC disconnected). He mentioned it was pulled from a TV with bad buffer boards, so his was likely a bad SC board too I'm guessing.

Any suggestions as to where to start looking for shorts on my SC board?

[Alastair E]

Re: Panasonic TH-50PX80U SC board troubleshooting

Any/All the heatsink mounted parts and the larger SMD transistors/diodes on the board.

[tw2005]

Re: Panasonic TH-50PX80U SC board troubleshooting

I found a guy locally that had a compatible used SC board but it displays exactly the same symptoms (7 blinks with buffer boards disconnected, solid red with SC disconnected). He mentioned it was pulled from a TV with bad buffer boards, so his was likely a bad SC board too I'm guessing.

Any suggestions as to where to start looking for shorts on my SC board?

you can't run these with either sd/su removed or they 7 blink

Read this document as they have the correct procedure

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

you can't run these with either sd/su removed or they 7 blink

Read this document as they have the correct procedure

Thanks for this! I was unable to find the PX80U procedure so I used the closest troubleshooting guide I could find. Looks like I will need to re-test...

[braxton]

Re: Panasonic TH-50PX80U SC board troubleshooting

So now I added the jumper from buffer floating ground to SC L801 coil and I get the same result (7 flashing lights with only both buffers disconnected and jumper in place, bot solid red when SC 2 and SC20 cables disconnected.

Still points to a bad SC board, although the other board I tested may be OK as I didn't use the jumper when testing that one.