P55VT30 connection test question.

[kdcfamily]

I am looking to find a person with a VT30 in working condition that does repairs and would be willing to check a connection for me on the SC board. I've just recently had repair work to the SC board and SU board. The SD board was ok he said.
I'm a person who checks work if the first try was a fail. He failed to check his work the first time and when I received it all of his work went to waste because there was still a short on the SC board.
Here lies my concern.

SD42 pin 9 is grounded/short with SU41 plugged into the SC board. When I unplug SU41 from the SC board, the SD42 pin9 no longer shows a short.
Only when the SU board is plugged into the SC board does SD42/SC42 show a short. I've checked all the pins on the SU board and they are all good when hooked up.
I am still concerned there is still a short in the SC board, but it won't burn everything up till 3 months later.. Guess I'm pessimistic.

[tw2005]

Re: P55VT30 connection test question.

I am looking to find a person with a VT30 in working condition that does repairs and would be willing to check a connection for me on the SC board. I've just recently had repair work to the SC board and SU board. The SD board was ok he said.
I'm a person who checks work if the first try was a fail. He failed to check his work the first time and when I received it all of his work went to waste because there was still a short on the SC board.
Here lies my concern.

SD42 pin 9 is grounded/short with SU41 plugged into the SC board. When I unplug SU41 from the SC board, the SD42 pin9 no longer shows a short.
Only when the SU board is plugged into the SC board does SD42/SC42 show a short. I've checked all the pins on the SU board and they are all good when hooked up.
I am still concerned there is still a short in the SC board, but it won't burn everything up till 3 months later.. Guess I'm pessimistic.

pin 9 goes to vfg when they are connected as far as i can see this is the detection for when either buffer board is disconnected and shuts the TV with 7 blink. It's the same as shorting the 2 pins at sc50 so looks normal to me.

Pins to check for short would be SU 2,6,8. SD 6,2,1 with respect to the grounding bolts that attach them to the Sc board

[kdcfamily]

Re: P55VT30 connection test question.

So I'm assuming you're saying with SU/SC41, SD/SC46, SD\SC42 all plugged in, the pin9 of SD/SC42 shows a ground when testing off of the floating ground? If so, that's good to know. I checked the pins 1, 3, 5 of SU/SC42 and they showed a ground if I remember right. I'm not at the TV right now so I can't verify.
It's the pin 9 that concerns me. I can't read the dang schematics even with a magnifying glass.. Guess my printer doesn't go small enough to print.

[tom66]

Re: P55VT30 connection test question.

I think it would also be a good idea to test from floating ground to all the buffer board output pins.

[kdcfamily]

Re: P55VT30 connection test question.

I checked all the output ribbon pins on the SU and SD boards from the floating ground without the SC board connected. All showed no ground. It's the SC board that has had input and output damage on it. He's done a good job of repairing the damages I suppose, but I'm always skeptical.
If it has a 90 day warranty... it breaks at 91.
When I verify everything is in working condition, it's use the new screws and Loctite Purple...

[kdcfamily]

Re: P55VT30 connection test question.

I'll connect the boards together through SU41, SD42, and SD46, and ribbon when I get a chance and retest all of the outputs on the buffer boards. He did repair on the SU board also since I forgot to mention that. The SD board a checked out fine.

[tw2005]

Re: P55VT30 connection test question.

The schematics are hopeless in these later manuals, however go to the block diagram and you will see the pins of significance. pg43. I can assure that pin 1 SU and pin 9 SD are tied to Vfg , have a look. If there is no short from the ground plates on the buffers to the output pins at the panel side then they are good. If you're worried about them being connected to the SC for a tes, you can leave them unplugged and not earthed(4 bolts removed) jumper the SC50 pins, and turn the TV on. If it stays on without a shutdown error blink then SC passed, only do it long enough to confirm. (30sec max)

I don't know how else you are going to check if the board has been repaired correctly or not unless you know how to fix them yourself.

Did you get new screws or the correct ones because part of the issue with these is the bolts used work loose and the board then has a bad earth and blows up.

[kdcfamily]

Re: P55VT30 connection test question.

He sent a new screw set. Whether they're the correct screws, I can only hope. They're gold in color like brass. I'm going to use Loctite Purple with them to ensure they don't back out unless I back them out. Purple is low set strength.
I have Loctite red and my wife asked why I don't use it instead. Had to explain to her I wasn't ready to torch it. Yet....

I'll look at 43 tonight.

[kdcfamily]

Re: P55VT30 connection test question.

Ok. All hooked up. All my buffer outputs check out with no short. SC/SD 42 has pin 9 short. SC/SU 41 pin 1 shows a short.
I'm not sure about testing the SC board through jumping the SC board through SC50 because with everything hooked up the SC50 shows to be a direct short like it's already jumped.
I've powered the TV on and it's working, but I have a feeling this is short lived.