Phystudent
New Member
I am working on a MA 5100 with the 2.5A slow blow fuse burning out. Serial number 29H36. Transformer labeled with the initials CSL on may 30th 1980.
Three of the four output transistors were leaking so I replaced them. However, when using a dim bulb tester there still seems to be an issue. With the dim bulb tester it shows I am getting approx 4 vDC at the speaker terminals with 6.75 vAC powering the transformer.
There is alot of black gunk/residue covering the wires leading out of the transformer(159-069), and the two channel power output boards(128-042) have some blackening near the resistor end of the boards. The 6 remaining transistors near the output boards are not leaking/test normally.
I have been working with two schematics that are far apart 22H and 30H, so that has been troublesome, but I am managing.
I am looking for advice on my next steps. I am leaning towards reworking the output boards or rebuilding the multicaps. Should I be pulling/testing diodes, resistors, and smaller caps first? Any direction from here would be greatly appreciated.
Three of the four output transistors were leaking so I replaced them. However, when using a dim bulb tester there still seems to be an issue. With the dim bulb tester it shows I am getting approx 4 vDC at the speaker terminals with 6.75 vAC powering the transformer.
There is alot of black gunk/residue covering the wires leading out of the transformer(159-069), and the two channel power output boards(128-042) have some blackening near the resistor end of the boards. The 6 remaining transistors near the output boards are not leaking/test normally.
I have been working with two schematics that are far apart 22H and 30H, so that has been troublesome, but I am managing.
I am looking for advice on my next steps. I am leaning towards reworking the output boards or rebuilding the multicaps. Should I be pulling/testing diodes, resistors, and smaller caps first? Any direction from here would be greatly appreciated.