Zenith Wax-Paper Capacitor Restuffing
antique radio restoration logs
Here is my process for restuffing Zenith and other wax-sealed paper capacitors in order to
maintain the original under chassis appearance of the radio. In cases where an original Zenith capacitor
has been replaced during servicing, I try to find a suitable original dud in my parts bin and restuffed that
capacitor. I collect branded capacitors (Zenith, Philco, and others) just
for this purpose. I have been able to purchase Zenith and other branded
duds from collectors who do not restuff capacitors on Antique
Radio Forums and on eBay. In most cases I found a dud with the part number listed in SAMS or Riders/Nostalgiaair.org.
If I do not have the exact part, I substituted a capacitor with a similar
Zenith part number having the same capacity and voltage rating. My re-stuffing process is as follows:
- The original capacitor is removed from the radio, and the required lead
length and any spaghetti sleeving use and its length noted. I also
document which capacitor lead (outside foil) goes to which terminal.
- The low melting point wax from each end is melted and removed using an old
25 watt soldering iron.
- The original wire leads are removed, as well as any remaining wax.
The leads are normally attached to the foil roll using a low melting point
metal or solder. The heat of the soldering iron used to remove the wax
will normally release the leads also.
- While the wax is still molten, a small screwdriver is used to push out the
original paper-foil roll. In some cases, the contents comes out when the leads
are pulled out.
- The original cases are then cleaned out, and any wax and dirt on the
outside removed by gently heating the body over a small alcohol lamp and
wiping with a paper towel while still molten. At this point, the cases
look like this:
- If the required lead length is longer than that of the replacement
capacitor, a piece of bus wire is attached before re-stuffing (the splice
being hidden inside the case).
- The replacement capacitor is wrapped in a narrow strip of
paper towel in order to keep the new capacitor centered and to keep it from falling out. Here
are the finished capacitors from another Zenith before sealing the ends.
- The finished capacitor is then sealed with melted rosin (salvaged from
early RCA Superhet catacombs, and donated by or purchased from members on Antique
Radio Forums). I do NOT recoat the outside of the rebuilt
capacitors with wax (I'm not sure what was originally used - probably