We had a short between VS and ground on the Y-sustain.
We replaced the board with a known good one we had from another tv we had fixed with a different issue. So we know for sure that the issue is isolated to this board.
We took out some of the IGBT transistors and found shorts on them. Went ahead and replaced them without success, they blew immediately again. We went and performed the same repair again and replaced one additional transistor that ended up failing after the first replacement attempt. We now get good steady voltages from the power supply, and none of the components are blowing anymore, however we only get 115V for the VSCan when it should be 193 and only get 27 volts for the vsch when it should be 45 or so.
Now here is the odd thing, those voltages do appear correctly for about 5 seconds and we do indeed get 193 volts on the VSCAN and 45 or so on the VSC test point as well, however this only occurs after you press the power button to turn it back off. Once you try to turn it back off, the voltages go to the correct amount and then after 5 seconds start going down to 0v
We then replaced U5000 and U5013 from the shop jimmy kit and still same symptoms.
We checked all of the IC chips on the buffer board portion of the set and found no shorts or could not see any visual defects on any of the chips.
Has anyone seen this problem before or would know where to go from here? I am thinking we may not be checking the IC chips properly or something else is going on that we just don't understand.
Thank you
-Nick
We replaced the board with a known good one we had from another tv we had fixed with a different issue. So we know for sure that the issue is isolated to this board.
We took out some of the IGBT transistors and found shorts on them. Went ahead and replaced them without success, they blew immediately again. We went and performed the same repair again and replaced one additional transistor that ended up failing after the first replacement attempt. We now get good steady voltages from the power supply, and none of the components are blowing anymore, however we only get 115V for the VSCan when it should be 193 and only get 27 volts for the vsch when it should be 45 or so.
Now here is the odd thing, those voltages do appear correctly for about 5 seconds and we do indeed get 193 volts on the VSCAN and 45 or so on the VSC test point as well, however this only occurs after you press the power button to turn it back off. Once you try to turn it back off, the voltages go to the correct amount and then after 5 seconds start going down to 0v
We then replaced U5000 and U5013 from the shop jimmy kit and still same symptoms.
We checked all of the IC chips on the buffer board portion of the set and found no shorts or could not see any visual defects on any of the chips.
Has anyone seen this problem before or would know where to go from here? I am thinking we may not be checking the IC chips properly or something else is going on that we just don't understand.
Thank you
-Nick
Comment