• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.



2010-11-04 9:10 pm
A former friend borrowed my hybrid integrated amp for the weekend (big mistake) and managed to damage it. Among other things he disconnected the speakers while the amp was on and the volume was high. He is unsure when the amp stopped working (it was a party he borrowed it for). Anyway, if the amp was damaged because of the no load issue, where would I look for damage? I tested all main transistors and a bulk of capacitors to no avail. There is power to the amp (LED's are on) and the two tubes in the preamp section are lit though they don't seem as bright as before.

Transistor outputs can normally cope with no load, but may be damaged by a short circuit. Valve outputs are opposite, short normally does no harm but no load causes excessive voltages which can damage the output valves or output transformer. Output valves can be easily replaced. Output transformers are expensive!

It might help if you tell us which amp you are talking about. We are clever, but mind reading from this distance is not too easy.