Learning to troubleshoot buffer boards (LJ41-09470A)

[Pioneerx01]

I am new to TV diagnostics, but I am learning. Currently I am trying to get handle on diagnosing Y buffer boards. I am looking at LJ41-09470A, see attached picture for details. When the board was in the TV none of the pins in the three white connectors showed as shorted to chassis ground.

I have since taken the buffer board out. None of the IC show visible signs of malfunction (blown, melted, pinholes,...) Now is where the uncertainty comes in. When I test for shorts on the pins alone, I put one probe on the first pin (black dot) and I see most of the other pins are shorted (red dots). I also see short in one of the ribbon connectors.

Am I going about this the right way? Is this buffer bad? Can you point me to good resource where I can learn more about diagnosing other parts as well?

Thanks
Peter

[newtothis]

Re: Learning to troubleshoot buffer boards (LJ41-09470A)

DMM to continuity/diode mode.

Black to pad around screw hole
Red down the pins on the ribbon connector

[budm]

Re: Learning to troubleshoot buffer boards (LJ41-09470A)

If you look at the pins of the connector and how they are soldered to the copper traces, you can see that lots of them are solder to the same copper plane so it will show as shorted circuit. You really need he diagram of the board or at least the labels for each pin.
May be trying to get the service manual for the set to see what the pins are for.

[Pioneerx01]

Re: Learning to troubleshoot buffer boards (LJ41-09470A)

DMM to continuity/diode mode. Black to pad around screw hole Red down the pins on the ribbon connector

There are two screw holes with copper ring around them, but they are isolated from the board and each other. I cannot get continuity between them, so I am not sure they will be good for testing. Should I put the board back, connect it to Y-SUS and test for shorts between chassis ground and ribbon connectors? However, none of the three white connectors shown a short when it was all hooked to the TV, so I am not sure how the ribbons would show short either in this set-up.

If you look at the pins of the connector and how they are soldered to the copper traces, you can see that lots of them are solder to the same copper plane so it will show as shorted circuit. You really need he diagram of the board or at least the labels for each pin.
May be trying to get the service manual for the set to see what the pins are for.

You are correct, they are. I do not have the diagram, and pins are not labeled anywhere on the board.