hi guys , new-ish member here with a recently purchased HH IC100 amp circa 74 -75.
Amp has been working fine for long periods and is out of the shell just now for a clean and visual inspection.
The power amp board is AO3103/7 variant with two [driver i think?] heatsinked transistors numbered BD711 [ uppermost] and BD712.
Earlier on i tried a treble booster through the amp at low volume and saw smoke from the power board and amp stopped working.
Fuses all ok but noticed R26 [ 10 k ] and R10 [ 100r ] looking burnt so replaced them and amp is now working again.
However , the transistor near these resistors numbered BD711 is getting really hot even after just a short time of playing.........it's lower twin BD712 is very cool in comparison.
Can anyone with experience of these amps advise what the problem may be ?
many thanks !
Amp has been working fine for long periods and is out of the shell just now for a clean and visual inspection.
The power amp board is AO3103/7 variant with two [driver i think?] heatsinked transistors numbered BD711 [ uppermost] and BD712.
Earlier on i tried a treble booster through the amp at low volume and saw smoke from the power board and amp stopped working.
Fuses all ok but noticed R26 [ 10 k ] and R10 [ 100r ] looking burnt so replaced them and amp is now working again.
However , the transistor near these resistors numbered BD711 is getting really hot even after just a short time of playing.........it's lower twin BD712 is very cool in comparison.
Can anyone with experience of these amps advise what the problem may be ?
many thanks !