12-21-2015, 01:13 AM
I'm working on a Fisher 700-T, and I found this site via Ron's excellent restoration thread here. I have two questions:
1) This is my first restoration, and I've read plenty about replacing the electrolytics. I've never seen a bad cap before, but I'm guessing this one is no good:
[Image: https://lh3.googleusercontent.com/-wDL03...520Cap.JPG]
Yes? It's C20 on the schematic (Serial 10001):
[Image: https://lh3.googleusercontent.com/-ayvuo...2520PS.JPG]
It appears to be smoothing after the diode bridge. I had done a visual inspection before powering on, but missed this one. There are smoothing caps before it (for the +63V supply) and a fuse and other smoothing caps after it (for the +15V, +24V and +30V supplies), so I think I just lucked out.
2) Everything seems to work great, except the "Selector" switch. It appears to be stuck on "FM AUTO". It seems the aluminum selector shaft is frozen in a collar that is secured to the mounting bracket.
I thought, "Great! I can handle mechanical issues." Then I started looking closer... it looks like the stack of sections have dozens of soldered connections to various parts of its surroundings. And I don't think I can slide the shaft in or out of the mounting. One end of the shaft has a retaining ring (arrows):
[Image: https://lh3.googleusercontent.com/-Adp6j...20Ring.JPG]
The other end, which runs through the selector disks, has a crimped-on spring (1), which presses a ball bearing (2) in a captive ring (3), and rolls in crimped detents (red highlights) of a plate (4). A large nut grabs the mounting bracket; a small nut on the other side backs it up (previous pic):
[Image: https://lh3.googleusercontent.com/-Ylf27...etents.JPG]
So.
Does anybody have some magic incantation that's useful here? I used a toothpick to wick a little WD-40 in, at the retaining ring and the plate, but it's not any better. I can grab the D-shaped shaft end and turn it gradually, while bracing the bracket. The ball bearing and spring appear to move properly, riding across the detents, but golly it's difficult! The collar and shaft look clean, and the grease (lithium?) at the detents is still goopy.
I have verified that the phenolic disks and rings, and the wipers and contacts are all free. They need cleaning, but they're free to move.
Suggestions?
Thanks,
Devin
1) This is my first restoration, and I've read plenty about replacing the electrolytics. I've never seen a bad cap before, but I'm guessing this one is no good:
[Image: https://lh3.googleusercontent.com/-wDL03...520Cap.JPG]
Yes? It's C20 on the schematic (Serial 10001):
[Image: https://lh3.googleusercontent.com/-ayvuo...2520PS.JPG]
It appears to be smoothing after the diode bridge. I had done a visual inspection before powering on, but missed this one. There are smoothing caps before it (for the +63V supply) and a fuse and other smoothing caps after it (for the +15V, +24V and +30V supplies), so I think I just lucked out.
2) Everything seems to work great, except the "Selector" switch. It appears to be stuck on "FM AUTO". It seems the aluminum selector shaft is frozen in a collar that is secured to the mounting bracket.
I thought, "Great! I can handle mechanical issues." Then I started looking closer... it looks like the stack of sections have dozens of soldered connections to various parts of its surroundings. And I don't think I can slide the shaft in or out of the mounting. One end of the shaft has a retaining ring (arrows):
[Image: https://lh3.googleusercontent.com/-Adp6j...20Ring.JPG]
The other end, which runs through the selector disks, has a crimped-on spring (1), which presses a ball bearing (2) in a captive ring (3), and rolls in crimped detents (red highlights) of a plate (4). A large nut grabs the mounting bracket; a small nut on the other side backs it up (previous pic):
[Image: https://lh3.googleusercontent.com/-Ylf27...etents.JPG]
So.
Does anybody have some magic incantation that's useful here? I used a toothpick to wick a little WD-40 in, at the retaining ring and the plate, but it's not any better. I can grab the D-shaped shaft end and turn it gradually, while bracing the bracket. The ball bearing and spring appear to move properly, riding across the detents, but golly it's difficult! The collar and shaft look clean, and the grease (lithium?) at the detents is still goopy.
I have verified that the phenolic disks and rings, and the wipers and contacts are all free. They need cleaning, but they're free to move.
Suggestions?
Thanks,
Devin
