[Hallicrafters] Cap replacement secret

[Craig Roberts]

Well, my SX-42 is playing away merrily. I completely re-tubed it, so am 
burning in the "valves" and new components before aligning the set 
tomorrow evening. (I suspect you're right, Jon, the model numbers of the 
SX-42 and parlor version SX-62 do seem to refer to the number of steps 
in the alignment procedure :-) ). I just hope my dottering old 
AN/URM-25D generator has enough life left in it to make it through.

Okay -- several guys have asked about the cap replacement secret, so 
here it is.  While this applies specifically to the two paper caps 
buried between sections 8 and 9 of the SX-42 bandswitch and the 
underside of the chassis, the method works in other awkward venues, too.

These particular SX-42 .05 MFD capacitors use braid, not wire,  leads 
(to supress oscillations). These special leads, employed in all but the 
earliest SX-42s, made the caps' replacement especially easy.

First, using desoldering braid, unsolder the ground end of each cap. 
These caps are grounded to very easily accessible brackets just under 
the receiver's left side panel (which should be removed to facilitate 
this recapping). Once those lead ends are free, GENTLY pull the paper 
caps up out of the bandswitch until their opposite, still-connected 
leads are exposed. I emphasize that this step must be done very gently 
to avoid breaking the still-connected leads. Then, free those leads by 
snipping off the old capacitors as close to the body as possible. The 
shellaced insulation tubing can now be slipped off the leads.

The replacement caps are plastic tubular, 630V devices (from IC, 
Mallory, etc.). These little yellow guys have a couple of advantages (in 
this circumstance) over the wildly popular Orange Drop types. The 
tubular caps are quite a bit smaller, making them a much easier fit into 
tight spaces, and their thinner wire leads are easier to maneuver, wrap 
and solder.

This cap swap also requires lengths of heat shrink tubing slightly 
larger in diameter than the replacement caps and as long as the 
still-connected leads.

Cut one lead of each cap to about a 1/4  of an inch or a little longer. 
Bury the shortened lead in the free braided lead and solder quickly. 
Then slip the heat shrink tubing over the new cap and down onto the 
still-connected lead as far as it will go. Again, working gently, push 
the new cap back down into the cavity between the switch and the chassis 
bottom. Bend the "top" lead of the cap 90 degrees at the cap body and 
solder it onto the grounding bracket.  That's it!  It takes about as 
long to do as to describe how to do it.

This same method can be used with wire leads on old caps, too, but the 
odds of stressing and breaking the old leads are increased.

This splicing method is contrary to my usual and purist-preferred "strip 
the old component out and down to the terminal" approach, but sometimes 
this is necessary to avoid possibly problematical and damaging 
disassembly of components. As one of you so wisely counseled, being as 
non-invasive as possible is best.

Tomorrow night, I'll let you know how the alignment went.

Thanks again for your help and encouragement.

73,
Craig
W3CRR