Out of rehab into recovery.
So the amp is working better than it ever has for us. It was gifted to my son 4 years ago but it had not seen much love in its life for quite some time before that, as it had been relegated to the garage, shed and who knows where else before we gave it a decent home.
Any how, this is what I did.
I could not measure any sensible continuity between the fuse posts so decided to replace them with some scrap I had kicking around. Not an ideal match but they work. As can be seen the corrosion was quite bad and I wonder how the thing actually work in the past months. With the fuses out I measured the no load idle current at 1.8A so something was up. I removed the cabling from the main TRs which all had ~0.4V forward drop across each junction which I guess is ok. The terminal post bolts were also replace due to corrosion while they were out.
On to replacing parts, I pulled all the electrolytics and tested them (get yourself one of the shown cheap testers if you don't have such a thing). Both the 10v 47uF caps were dead and the 6.8 didn't look too good, so I replaced them. The local electronics shop only had one 6.8. For the time being, the best of the two is back in for now (C6). I also pulled the 150pF which looked good showing 144pF on the tester so that's back in. The only real problem is that possibly due to its hard life in some cold dark damp place the tracks/pads easily lift from the PCB when soldering.
The amp is now playing very well and loud, with no heating while idle.
My question is how hot does the back panel get when playing at volume, I know this is a bit subjective with out a proper reading, but it was quite warm after being played hard on stage setting for 10 mins or so. I pulled it from the cabinet and the two TIP drivers where more than warm but not burning to the touch (not uncomfortable and no smell)
would this be acceptable ?
... Simon
So the amp is working better than it ever has for us. It was gifted to my son 4 years ago but it had not seen much love in its life for quite some time before that, as it had been relegated to the garage, shed and who knows where else before we gave it a decent home.
Any how, this is what I did.
I could not measure any sensible continuity between the fuse posts so decided to replace them with some scrap I had kicking around. Not an ideal match but they work. As can be seen the corrosion was quite bad and I wonder how the thing actually work in the past months. With the fuses out I measured the no load idle current at 1.8A so something was up. I removed the cabling from the main TRs which all had ~0.4V forward drop across each junction which I guess is ok. The terminal post bolts were also replace due to corrosion while they were out.
On to replacing parts, I pulled all the electrolytics and tested them (get yourself one of the shown cheap testers if you don't have such a thing). Both the 10v 47uF caps were dead and the 6.8 didn't look too good, so I replaced them. The local electronics shop only had one 6.8. For the time being, the best of the two is back in for now (C6). I also pulled the 150pF which looked good showing 144pF on the tester so that's back in. The only real problem is that possibly due to its hard life in some cold dark damp place the tracks/pads easily lift from the PCB when soldering.
The amp is now playing very well and loud, with no heating while idle.
My question is how hot does the back panel get when playing at volume, I know this is a bit subjective with out a proper reading, but it was quite warm after being played hard on stage setting for 10 mins or so. I pulled it from the cabinet and the two TIP drivers where more than warm but not burning to the touch (not uncomfortable and no smell)
would this be acceptable ?
... Simon