Hey, BigThinker, good to meet you!
Have the amps been used recently, or have the been out of service for months so the power-supply capacitors may need to be reformed?
Also: DBerning wrote in the
Project Discussion: My Dead Dynaco ST-70 thread:
Quote:
A good cheap tool useful for testing amps where a power problem may exist is to make up a fixture that has a light bulb such that the amp can be powered up with the light bulb in series with the power. A lamp with one of the power conductors is cut and a male AC connector bridges the two ends of the cut wire serves as the socket to plug the amp under test into. This is also useful for reforming capacitors in amps that have not been powered up in a long time. IF the lamp comes on very bright there is a short in the amp's power supply or transformer. If the lamp dims shortly after turning on, this usually indicates that things are OK to remove the lamp and plug the amp directly into the wall outlet. Do NOT do this with switching power supplies. Typically I use a 100-watt lamp.