View Full Version : What kind of caps...


zacster
04-01-2005, 07:47 PM
should I use to replace the paper ones in the set? Should I just use the Rat Shack equivalents? Or is there a specific type that works better, such as orange drops? Or should the physical size determine it? I've tried replacing caps in my Bottlehead and Dynaco gear, but had a bit of trouble with physical size. I would guess that audiophile grade caps are NOT necessary.

I'm going to replace the papers and the electrolytics, slowly and carefully, replace the power cord and put a fuse in, and then try turning it on using the light buld method. Then I'll cross my fingers that the picture tube gives a flicker. What size fuse should I use? I would imagine this thing draws a lot of current.

(See my Dumont thread below for more info.)

Eric H
04-01-2005, 08:30 PM
Orange drops are great but expensive, also they can be hard to fit in tight spots.

AES http://www.tubesandmore.com/ sells some nice yellow Polyester or Polypropylene caps that work great and are easy to work with. They also have Orange Drops and Electrolytics.

Justradios sells basically the same caps as AES but cheaper: http://www.justradios.com/

For the paper caps you can use the 630 volt caps to replace anything 630 volts or less. The new 630 volt caps will be smaller than the old 200 volt caps of the same value.

For the electrolytics use only equal or slightly higher voltage replacements.

zacster
04-01-2005, 09:11 PM
Thanks, Eric.

One more question. Do any of you replace tube sockets? I had problems with my Dynaco that new tube sockets fixed. With 25 tubes in the Dumont, that's a lot of sockets.

wa2ise
04-01-2005, 10:12 PM
Thanks, Eric.

One more question. Do any of you replace tube sockets? I had problems with my Dynaco that new tube sockets fixed. With 25 tubes in the Dumont, that's a lot of sockets.

Not usually. Only if a socket is found to be bad. Those cheap wafer sockets are actually pretty good. You can tighten the contacts if need be. Take out the tube, squeeze the contacts a little and reinsert the tube. Tube sockets usually didn't see all that many inserts/removal cycles and the springiness of the contacts should still be as new.

When recapping, I don't try to remove all of the old cap's leads from tube socket terminals. I just clip it off at the terminal and solder the new one atop. Terminals are fairly fragile and not designed to take the stresses of lead removal.

zacster
04-02-2005, 08:01 PM
I finally opened up the chassis to see what was inside and it was a mess. All of the paper caps that I saw were leaking, and 50 years of dust covered everything. I couldn't identify all of the caps in the picture from the Sams folder, but I'll double check the schematic when I get to them. I also uncovered a tag on the high voltage lead warning about the 13000 volts, as if the 600 volts wouldn't kill you as well! I'll stay away from that one.

I guess after working on this, the 300B amp with 16 parts will seem like a piece of cake.