TC-P55GT30 Made a pop and now dead

[Budsdad]

I bought this TC-P55GT30 new in 2011. It made a pop sound and now is dead. It makes no clicks and no led. I am a retired auto/truck tech. I have a fluke DVOM. I will attach the circuit board picture. I am hoping for guidance on where to start checking voltages etc. I have looked over the caps etc and don't see anything obvious. Only odd thing I see is one of the fans is missing a mounting screw and standoff. I didn't find them under the back cover anywhere. Wife says to just replace it but I enjoyed the picture quality and have a bunch of 3D pictures and movies. Thanks

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

No idea why the image posted upside down. Not sure how to fix it. The original image is not.

[dskall]

Re: TC-P55GT30 Made a pop and now dead

Need good pictures of power board in center of picture.

[tw2005]

Re: TC-P55GT30 Made a pop and now dead

Try checking the SC2 pins and see if they're shorted or the 30F131, RJP30H2 transistors on the SC. Don't usually loose the front LED with the SC , 7 blinks normally.

I have had a bad Pboard with a very small smd FET fail on it and that caused no stdby LED but it was not mine so not sure if any noise was associated with that.

SC failure very common.

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

To check the SC2 pins I disconnect the connector first? Then check between the pins on the SC board for continuity to a ground screw on the board? Just trying to be careful. Thanks. Here is a better picture of the board.

[tw2005]

Re: TC-P55GT30 Made a pop and now dead

Simply probe across the terminals. Same as the transistors they have 3 points of contact pick 2. Unpowered just checking for low resistance or dead short.

[tw2005]

Re: TC-P55GT30 Made a pop and now dead

If it's a shorted board stopping it you could isolate it and see if symptoms change.

[tvtimmy]

Re: TC-P55GT30 Made a pop and now dead

That board is the power supply or "p" board. Disconnect sc2 at the other end, that is the sc board. Put a probe one one pin and one on the other. If you hear a beep for more than 3 seconds you have a short on the board. Check the parts marked 30f131 by testing leg to leg and leg to tab for continuity. Any beep is bad.

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

I checked across the 2 pins at SC2 and they show full continuity(shorted). My old Fluke 73 doesn't have beep. I checked the 3 30f131s closest to the SC2 and they all showed continuity leg to leg and leg to tab. Surprised with the results I rechecked then with an analog VOM with the same results. Is unusual for them all to be shorted all ways? Are there more I should check or can we assume the SC board needs repair?
I had seen in another thread here (the same TV and same no LED/pop symptoms) that you should check for 5vdc on pin 6 of P6. I had only 1.9 vdc and when I checked it sounded like a relay on P2 clicked sometimes. In that thread they replaced P1 then P2. Unlike mine their SC was OK. Seems as though most SC failures have the 7 blink LED. Concerned that I have no LED, relay click etc.

[tvtimmy]

Re: TC-P55GT30 Made a pop and now dead

Watch this video. It shows how to repair a similar board. I just use a 45 watt soldering iron and no bottom heat. The diodes will read bad untill you lift all the bad parts that have a Q in front of the number.

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

I don't think I will be repairing the board. I hate to admit I am not as steady and don't see as well as I once did. My comp engineering student son works on PCBs in the summer, wife won't wait that long. I will have to send the board for repairs. Is there a way I can tell if other boards etc are damaged before I spend the money on the SC board? Recommendation on where to send the board? Thanks

[tvtimmy]

Re: TC-P55GT30 Made a pop and now dead

Yes. You have to check the buffer boards, SU & SD. There are 4 screws that attach the buffers to the SC board. They are the floating variable grounds. Two on top two on bottom. Take them out and remove the 3 white connectors to the SC. Put a probe on one of the 2 screws on the top board and flip up the latchs on that board that go to the golden ribbon cables. If your meter has no beep function I think you can use ohm scale to find shorts. Take other probe and rake across the pins of the connectors. Repete on the bottom one. This model is known for one buffer going bad.

[tw2005]

Re: TC-P55GT30 Made a pop and now dead

Check the ss there is a fet could be q101 smd transistor I have had several

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

Yes. You have to check the buffer boards, SU & SD. There are 4 screws that attach the buffers to the SC board. They are the floating variable grounds. Two on top two on bottom. Take them out and remove the 3 white connectors to the SC. Put a probe on one of the 2 screws on the top board and flip up the latchs on that board that go to the golden ribbon cables. If your meter has no beep function I think you can use ohm scale to find shorts. Take other probe and rake across the pins of the connectors. Repete on the bottom one. This model is known for one buffer going bad.

Rack it down the pins of the unlatched ribbon connectors? Ribbons can stay in place? Thanks

[tw2005]

Re: TC-P55GT30 Made a pop and now dead

Check the ss there is a fet could be q101 smd transistor I have had several

short and go out in sympathy

[tvtimmy]

Re: TC-P55GT30 Made a pop and now dead

Yes leave ribbons in place. Make sure you dont hit the holes on the very ends of them, they are grounds and will make your meter beep and give you a false reading. Check the SS fet that TW2005 is referring to also.

[RJARRRPCGP]

Re: TC-P55GT30 Made a pop and now dead

I hope the PDP per-se didn't take a shit!

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

Yes leave ribbons in place. Make sure you dont hit the holes on the very ends of them, they are grounds and will make your meter beep and give you a false reading. Check the SS fet that TW2005 is referring to also.

I removed the screws to the SC board and checked for continuity between the ribbon connectors and a mounting screw (chassis ground) and found none. I checked twice slowly and found none. I didn't see any holes at the end though. I don't see the fet on the SS board so here is a picture. Thanks

[Budsdad]

Re: TC-P55GT30 Made a pop and now dead

I hope the PDP per-se didn't take a shit!

Me too! I had to google PDP LOL

[tvtimmy]

Re: TC-P55GT30 Made a pop and now dead

In the red.