I just finished repairing a RCA 42PA30RQ 42 inch plasma TV working and thought I would pass on what I found. It had the common problems of sound, no picture, and VS would not stay at 207V. I ended up repairing the Y Buffer board and the X Board.
The things I found while troubleshooting it are as follows:
- At least in this set, If the VS does not come on and stay on at 207 volts, there is a problem somewhere in one or more of the boards. You can disconnect both the Y and X boards and if the PS is good, VS will go to 207V and stay there.
- The X board gets its power from the Y Board. So if Vs comes up after removing the Y board, it does not mean the Y board is bad. It can be either the X or Y boards. You need to remove the X board first to see if Vs returns to 207V. If so, then the X board is bad and needs to be either fixed or replaced and the Y board is OK. Note, do not power up the set with a new or repaired X board until you get VS to stay at 207V without it. (Don't ask)
- So, if after removing the X board, Vs still does not come up, then the problem is either the Y board or the Y Buffer board. If VS stays at 207V after removing the Y Buffer, then the Y board is good and the Y Buffer board needs to be repaired or replaced. If not the Y board is bad and needs to be repaired or replaced. However, this does not mean the Y Buffer is good and it has to be tested. I wouldn't power up a good Y Board until I knew the Y Buffer was good.
Note: It appears that the Y Buffer can take out either or both the Y and X Boards. In my case it was the X Board. I haven't figured out why though.
The tests above only isolated a bad X Board or Y Buffer. Troubleshooting the X Board and Y Buffer board are as follows:
- The typical fault for the X Board appears to be that Q4001 & Q4007 (RJH30E2) are shorted. That's what my problem was. As noted before, if you power the board before you get VS to stay at 207V, you probably will end up with these two shorted again.
- There are many good instructions on this site to tell how to troubleshoot the Y Buffer Board for shorts. However, in my case, there were no shorts on the board, but it still caused Vs to go away. I noticed when I powered the set up, during the time when VS came up and then went away, there was an arc over on C5201 & C5402. So I decided to replace them. There was no markings on the Caps so it brought up the problem of what the values should be. Elsewhere on this site I found a picture of the board where the caps were replaced with a 0,2UFD 250V capacitor (like an Orange Drop). I don't know if that was an earlier or later version of the board. Anyway I replace the caps and VS came up to 207V. Replacing the transistors on the X board solved the rest.
- My Y Board was OK so I didn't have to fix it. But I would suspect that shorted output transistors would be a good guess.
The things I found while troubleshooting it are as follows:
- At least in this set, If the VS does not come on and stay on at 207 volts, there is a problem somewhere in one or more of the boards. You can disconnect both the Y and X boards and if the PS is good, VS will go to 207V and stay there.
- The X board gets its power from the Y Board. So if Vs comes up after removing the Y board, it does not mean the Y board is bad. It can be either the X or Y boards. You need to remove the X board first to see if Vs returns to 207V. If so, then the X board is bad and needs to be either fixed or replaced and the Y board is OK. Note, do not power up the set with a new or repaired X board until you get VS to stay at 207V without it. (Don't ask)
- So, if after removing the X board, Vs still does not come up, then the problem is either the Y board or the Y Buffer board. If VS stays at 207V after removing the Y Buffer, then the Y board is good and the Y Buffer board needs to be repaired or replaced. If not the Y board is bad and needs to be repaired or replaced. However, this does not mean the Y Buffer is good and it has to be tested. I wouldn't power up a good Y Board until I knew the Y Buffer was good.
Note: It appears that the Y Buffer can take out either or both the Y and X Boards. In my case it was the X Board. I haven't figured out why though.
The tests above only isolated a bad X Board or Y Buffer. Troubleshooting the X Board and Y Buffer board are as follows:
- The typical fault for the X Board appears to be that Q4001 & Q4007 (RJH30E2) are shorted. That's what my problem was. As noted before, if you power the board before you get VS to stay at 207V, you probably will end up with these two shorted again.
- There are many good instructions on this site to tell how to troubleshoot the Y Buffer Board for shorts. However, in my case, there were no shorts on the board, but it still caused Vs to go away. I noticed when I powered the set up, during the time when VS came up and then went away, there was an arc over on C5201 & C5402. So I decided to replace them. There was no markings on the Caps so it brought up the problem of what the values should be. Elsewhere on this site I found a picture of the board where the caps were replaced with a 0,2UFD 250V capacitor (like an Orange Drop). I don't know if that was an earlier or later version of the board. Anyway I replace the caps and VS came up to 207V. Replacing the transistors on the X board solved the rest.
- My Y Board was OK so I didn't have to fix it. But I would suspect that shorted output transistors would be a good guess.
