spaghetti
Active Member
I bought recently this amplifier sold as not working, but with clicking relay according to the seller. I did not test it. Right when it arrived I removed the precious VFET transistors, checked them and they're all still OK, so I put them aside.
I started replacing the killer diodes, then while I was at it I recapped the unit (expect for the 2 main big filter caps... there's some small ripple current but I think it's not an urgent issue) and replaced the trimpots with new ones.
Now I am testing the amp (no VFET installed yet) injecting the usual 1Khz sine wave and checking the results at the speakers terminal. with the scope. I see that the signal looks good as long as the volume is quite low, let's say up to 2 of 10, then it clips quickly and I get a distorted signal also on the other channel.
I checked all the transistors, diodes and resistors on both boards, replaced a few resistors that were out of spec, but found nothing serious.
I was wondering if it makes sense testing the amp without the VFET installed, or if the strange behavior is caused by their absence... but of course I don't feel like testing it with the VFET installed unless I'm confident that everything is OK.
Any suggestion/help is highly appreciated, thanks
Andrea
I started replacing the killer diodes, then while I was at it I recapped the unit (expect for the 2 main big filter caps... there's some small ripple current but I think it's not an urgent issue) and replaced the trimpots with new ones.
Now I am testing the amp (no VFET installed yet) injecting the usual 1Khz sine wave and checking the results at the speakers terminal. with the scope. I see that the signal looks good as long as the volume is quite low, let's say up to 2 of 10, then it clips quickly and I get a distorted signal also on the other channel.
I checked all the transistors, diodes and resistors on both boards, replaced a few resistors that were out of spec, but found nothing serious.
I was wondering if it makes sense testing the amp without the VFET installed, or if the strange behavior is caused by their absence... but of course I don't feel like testing it with the VFET installed unless I'm confident that everything is OK.
Any suggestion/help is highly appreciated, thanks
Andrea