FeedbackLoop | #106 - QSC USA 850 power amplifier repair @feedback-loop | Uploaded 3 years ago | Updated 4 days ago
The amp had output stages in both channels shorted. It turned out that 5 out of 16 power transistors failed. Driver transistors on the negative side in each channel failed as well and killed a couple of 6.8 Ohm resistors around them. After unsuccessful attempt to get cheap transistors from China on eBay, the amp was tested with 8 out of 16 output transistors in the output stages. This configuration worked fine, and now the question is about money: if we tolerate mixing old and new transistors, 5 replacement transistors from DigiKey will cost about $40. Replacing all 16 will be (almost) beyond economical repair. Let me know what you think. Thanks.
The amp had output stages in both channels shorted. It turned out that 5 out of 16 power transistors failed. Driver transistors on the negative side in each channel failed as well and killed a couple of 6.8 Ohm resistors around them. After unsuccessful attempt to get cheap transistors from China on eBay, the amp was tested with 8 out of 16 output transistors in the output stages. This configuration worked fine, and now the question is about money: if we tolerate mixing old and new transistors, 5 replacement transistors from DigiKey will cost about $40. Replacing all 16 will be (almost) beyond economical repair. Let me know what you think. Thanks.
