Hi everyone. I am struggling to understand the bias adjustment on this amp its affecting both channels and has duel power supply. The bottom line is its too high on the lowest possible setting with the bias pot it hovers around 35-40mV (should be 18mV) and takes about 10 mins to get there just creeping up at 0.1mv per second on the meter.
just mentioning the one channel, I've replaced the two driver transistors Q2,Q4 with the exact ones listed on the schematic and replaced the bias diode with a SV-04 which is a good replacement for a STV-04h which made hardy no difference and plus the voltages all seem correct.
Apart from the bias issue the amp runs very well and doesn't get that warm and sound great with loads of horse power.
So any help would be very welcome as I'm puzzled with it.
just mentioning the one channel, I've replaced the two driver transistors Q2,Q4 with the exact ones listed on the schematic and replaced the bias diode with a SV-04 which is a good replacement for a STV-04h which made hardy no difference and plus the voltages all seem correct.
Apart from the bias issue the amp runs very well and doesn't get that warm and sound great with loads of horse power.
So any help would be very welcome as I'm puzzled with it.
Thanks uchu007 for your reply. I have the service manual already thanks. This morning i set the preamp off set to zero it was slightly out but has made no difference to the bias at all, the output offset was adjusted sometime ago i forgot to mention that before.
There is four small transistors arranged in two pairs between the driver transistors Q10, Q12 - Q6, Q8 and on the schematic and has the word ASO above do you know what these do and what the word refers too?
There is four small transistors arranged in two pairs between the driver transistors Q10, Q12 - Q6, Q8 and on the schematic and has the word ASO above do you know what these do and what the word refers too?
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