Post by r2digital on Mar 30, 2024 9:19:01 GMT -5
i everyone, i’m hoping some one has the patience to point me in the right direction to repairing this fairly expensive boston acoustic msub
At first the off/on/auto switch was busted so i forced it into auto mode by bridging a connection on the main board and now the blue light comes on but i don't get any audio output. Does anyone one have any experience repairing this amplifier? I looked it over, checked some the of output transistors, some of the power resistors and cleaned that nasty conductive epoxy glue stuff off but not having much luck in the trouble shooting department. I did however find a part of the PCB that was discolored from heat that may be an area of interest. It consists of two transistors which you can see in the short videos i attached along with some pictures to my google drive. In the picture that has an area circled in red it is because sometimes after a little while that area would emit a high pitched whine for 15-20 seconds and then disappear
Looking for any help or guidance in how to repair this plate amp
Things i have done so far
Rail voltage +/-15V and VCC +/- 77.8
Replaced almost all electrolytics on preamp board
Replaced 2 caps on limiter
Replaced 2 filter caps on power supply
Replaced SMD caps on power supply (pre amp section near q01/q02
drive.google.com/drive/folders/1fx9ICpo1UH4mJoX8_hJFEv-s0_tVUBKF
drive.google.com/file/d/17QxlW7d4WM4KrGct4m44bL1P8yAKl4fM/view?usp=drivesdk <<<< Direct link to Schematic
At first the off/on/auto switch was busted so i forced it into auto mode by bridging a connection on the main board and now the blue light comes on but i don't get any audio output. Does anyone one have any experience repairing this amplifier? I looked it over, checked some the of output transistors, some of the power resistors and cleaned that nasty conductive epoxy glue stuff off but not having much luck in the trouble shooting department. I did however find a part of the PCB that was discolored from heat that may be an area of interest. It consists of two transistors which you can see in the short videos i attached along with some pictures to my google drive. In the picture that has an area circled in red it is because sometimes after a little while that area would emit a high pitched whine for 15-20 seconds and then disappear
Looking for any help or guidance in how to repair this plate amp
Things i have done so far
Rail voltage +/-15V and VCC +/- 77.8
Replaced almost all electrolytics on preamp board
Replaced 2 caps on limiter
Replaced 2 filter caps on power supply
Replaced SMD caps on power supply (pre amp section near q01/q02
drive.google.com/drive/folders/1fx9ICpo1UH4mJoX8_hJFEv-s0_tVUBKF
drive.google.com/file/d/17QxlW7d4WM4KrGct4m44bL1P8yAKl4fM/view?usp=drivesdk <<<< Direct link to Schematic
