Well I'm finally back after a little hiatus. I updated the schematic back on page 4.
All of my parts came in last week. I fired up the iron this weekend and went after it. First thing I had to do was modify the 3PDT switches. I drilled and tapped new 4-40 threads into them to match up to the existing chassis holes. All of the tubular caps were replaced as well as some of the ceramic discs. I used the Orange Drops for most, but for my own amps I use Xicon, CDE or Nichoson. I found the OD to be fairly large compared to the others so I most likely won't be using them by choice next time.
The first capacitor on the input power supply was a 50uF, which I found out after pulling it. When I was reading the original schematics, I thought it was a 30, so I bought a 33uF to go there. I've ordered a 47uF to replace it, and that should be here by week's end.
I replaced the power cord with a 3 prong one that I had extra. Snipped the end of it and soldered it in. When I first plugged the amp's power cord in, I noticed the power on light was lit. Figured out that the original switch I replaced operated its contacts opposite of the new switch. A quick swap of the throws fixed that.
I changed the rear jacks to be speaker out jacks per the amp owner's request. I actually like that much better.
There was a bit of hum when I first powered it up. Tweaking the hum balance pot eliminated it. Probing the tube sockets revealed a bad solder joint and stray wires for V3-6. The OT leads were also touching pin 5 occasionally, especially when I probed it. Wasn't a pretty sight or sound. Fixed that and no more issues there.
The volume pot works fine on the low end, produces some very nasty distortion in the middle, and has some creamy overdrive at the high end. I cleaned all the pots, but this pot just doesn't seem to want to clean up. Now I need to find a replacement that has a switch on it. Any recommendations? The value I measured across the leads was 85k audio taper, so I'm assuming it was/is an A100k pot, yes? Bass pot worked ok, measured A1M. Treble pot worked ok, measured A3.8M.
Trem circuit didn't work at first. Turns out the 3PDT switch has one of the throws not working. When I grounded the Trem speed pot, the tremolo worked nice. It has some decent speed adjustment, but it doesn't get as slow as I would like. Slowest is around 1/2 second, maybe a little longer than that. That pot measured A2.3M. Depth worked good. No thumping out of it until the last 10% of turn. Then I could only hear it when I didn't play anything. Otherwise, it was unnoticeable while playing.
So, later this week, I'll replace the trem on/off switch and install the 47uF cap on the first filter stage. Any ideas what the nominal values of pots should be? I may replace all of them, but I at least want to get the schematic correct. Got a lead on where to find the correct volume pot?
Thanks!
Here are a couple quick pix of the amp.