Just purchased this amp through a trade in BT. It is all original but has had the amp section serviced in years past. The issue is with the pre-amp section; Flipping the tone switch on causes a loud pop and the tone switches (bass & treble) are not functional. I just started looking at this but I would assume I have a faulty transistor. The pre-amp is also a bit noisy. I separated the unit to confirm this.
pre-amp board AWG-018 already has 2SC2240 transistors subbed in, pulled one and tested good. The rest look to be original on that board. Maybe one of the EQ/tone boards?
I have a caps list ordered and I see there's already some reputable parts lists made for this unit. I have many of the equivalent transistors on hand. Not going to go off subbing transistors for no reason but I might as well sub the 2sc1345 with ksc1845 on the filter board (they all tested good), maybe it will help the noise. This should be a pretty simple fix if I can narrow it down a bit.
pre-amp board AWG-018 already has 2SC2240 transistors subbed in, pulled one and tested good. The rest look to be original on that board. Maybe one of the EQ/tone boards?
I have a caps list ordered and I see there's already some reputable parts lists made for this unit. I have many of the equivalent transistors on hand. Not going to go off subbing transistors for no reason but I might as well sub the 2sc1345 with ksc1845 on the filter board (they all tested good), maybe it will help the noise. This should be a pretty simple fix if I can narrow it down a bit.