My son blew his Pioneer amp again a few months ago - it's driving big, inefficient HT speakers and once a few beers have flowed they hammer it. The power mosfets (IRF530 and IRF9530) in the right channel went short on both occasions.
I replaced them earlier, and then tried to set the idle current (see pic below for left channel - shows a bit more of the power rails). It has to be set to 10mA initially, and then 11mA after 5 mins. The left channel is fine, but I can get the right channel no higher than about 8.6mA at the full extent of the adjustment pot. When I replaced the mosfets, I did have this vague concern that they were failing for some reason further back in the circuit, so now I'm worried that there is another problem.
So I hauled out the circuit diagrams, but transistors aren't really my thing, and I'm not quite sure where to start. I would guess the right channel equivalents Q319/321? Could it just be that the new mosfets aren't too lekker? Any guidance will be gratefully received.
I replaced them earlier, and then tried to set the idle current (see pic below for left channel - shows a bit more of the power rails). It has to be set to 10mA initially, and then 11mA after 5 mins. The left channel is fine, but I can get the right channel no higher than about 8.6mA at the full extent of the adjustment pot. When I replaced the mosfets, I did have this vague concern that they were failing for some reason further back in the circuit, so now I'm worried that there is another problem.
So I hauled out the circuit diagrams, but transistors aren't really my thing, and I'm not quite sure where to start. I would guess the right channel equivalents Q319/321? Could it just be that the new mosfets aren't too lekker? Any guidance will be gratefully received.
