Dynaco ST-150: can't adjust bias
After running about an hour, I get a random loud pop every few minutes, and soft "rustling" noises (both channels). Adjusting bias, one channel will only drop to about 400ma (should be around 75) and the DC null adjustment at the speaker output will only get down to about 400mv (should be near zero, less than 25mv). The other channel is OK. With the noise in both channels, maybe the bias is unrelated? The affected channel runs hotter.
Maybe in a 40 year old amp, I should just replace all the electrolytic caps for starters, then the transistors?