FlaCharlie
Super Member
Finished restoring the Fisher 100T Pre/Tuner and the SA-16 amp. These were pulled from a console that I found on CL several years ago. Here are a few before and after pics.
As you can see the SA-16 had two dead output tubes that had to be removed in pieces. One was caused by a leaky coupling cap. Not sure what happened to the other. Unfortunately, most of the tubes were long past being useful. You can also see that the resistors in the heater circuit had gotten a little . . . uh . . . toasty. I'm guessing that the failed output tubes might have shorted their heaters and burned them up.
I decided to replace only the first PS cap since it deals with most all the current. I went with a 35uF Panasonic 500v poly. The other sections measured fine with ESR that was just as low as the new caps I would have used to replace them. So I decided to just leave them in, for now anyway. Replaced the .022 ceramic coupling caps with some nice .033 PIOs. I added a CL-80 thermistor and replaced the 100 ohm 10w PS resistor with a 150 ohm 20w to bring down the B+ a bit. The voltages before this were actually very close to those on the schematics but at those voltages the output tubes were being run at more than their 12 watt dissipation spec. Now they're just under the spec. Added some 10 ohm resistors to the cathodes and was able to identify four matched quads of NOS outputs.
The 100T was in better shape. Mostly I just made some changes to bring the voltages down to spec and replaced all the lytics. A few tubes were replaced. Despite not having the knowledge or equipment to align tuners, the FM sounds great and I didn't notice any problems when I A-Bed the new tubes with the old ones. I don't listen to radio much anyway. It's mono, of course, since it isn't equipped with the multiplex. I have a Sherwood S-3000 mono tuner too so I'm used to mono. The phono section sounds really nice too, although I don't have much recent experience with vinyl either.
As you can see the SA-16 had two dead output tubes that had to be removed in pieces. One was caused by a leaky coupling cap. Not sure what happened to the other. Unfortunately, most of the tubes were long past being useful. You can also see that the resistors in the heater circuit had gotten a little . . . uh . . . toasty. I'm guessing that the failed output tubes might have shorted their heaters and burned them up.
I decided to replace only the first PS cap since it deals with most all the current. I went with a 35uF Panasonic 500v poly. The other sections measured fine with ESR that was just as low as the new caps I would have used to replace them. So I decided to just leave them in, for now anyway. Replaced the .022 ceramic coupling caps with some nice .033 PIOs. I added a CL-80 thermistor and replaced the 100 ohm 10w PS resistor with a 150 ohm 20w to bring down the B+ a bit. The voltages before this were actually very close to those on the schematics but at those voltages the output tubes were being run at more than their 12 watt dissipation spec. Now they're just under the spec. Added some 10 ohm resistors to the cathodes and was able to identify four matched quads of NOS outputs.
The 100T was in better shape. Mostly I just made some changes to bring the voltages down to spec and replaced all the lytics. A few tubes were replaced. Despite not having the knowledge or equipment to align tuners, the FM sounds great and I didn't notice any problems when I A-Bed the new tubes with the old ones. I don't listen to radio much anyway. It's mono, of course, since it isn't equipped with the multiplex. I have a Sherwood S-3000 mono tuner too so I'm used to mono. The phono section sounds really nice too, although I don't have much recent experience with vinyl either.