Before making such test, as you've just did, I would thoroughly check if you can turn this amp unloaded at all especially for the long time.
Some of amplifiers may go to the high level of oscillations when no load is present hence buzzing takes place originally at collector output circuits of power transformer which IS quite distructive!
You may use a dummy load resistors(I guess you should get 25...50W/10Ohms) I always conduct such tests of reserviced amplifiers and once-in-a-while I burn them literally seing some smoke comming up due to some mistakes taken place during circuit repair or re-mount.
For you I'd suggest connecting such dummy load resistor 50W in your case(available at partsexpress.com or percyaudio.com). Turn on your amp with resistors connected at both LCH, RCH terminals wait and listen what's goning on:
if you see smoke, than something is a-miss... if you se no smoke than try to touch resistor but first bring your fingers close enough to the resistor surface to make shure you're not feeling the high heat. If the resistor is quite warm or hot than you're probably having the case with oscillations that you'll need to take care off either yourself or with experienced tech.
The reasons could be various with no exempt to shipping damage(the solder joints may get loose because of age and stress.
Some of amplifiers may go to the high level of oscillations when no load is present hence buzzing takes place originally at collector output circuits of power transformer which IS quite distructive!
You may use a dummy load resistors(I guess you should get 25...50W/10Ohms) I always conduct such tests of reserviced amplifiers and once-in-a-while I burn them literally seing some smoke comming up due to some mistakes taken place during circuit repair or re-mount.
For you I'd suggest connecting such dummy load resistor 50W in your case(available at partsexpress.com or percyaudio.com). Turn on your amp with resistors connected at both LCH, RCH terminals wait and listen what's goning on:
if you see smoke, than something is a-miss... if you se no smoke than try to touch resistor but first bring your fingers close enough to the resistor surface to make shure you're not feeling the high heat. If the resistor is quite warm or hot than you're probably having the case with oscillations that you'll need to take care off either yourself or with experienced tech.
The reasons could be various with no exempt to shipping damage(the solder joints may get loose because of age and stress.