[MRCA] Capacitor issues

[Scott Johnson]

I would not replace it, most of those old oil caps leak their mineral oil,
but as long as the capacitor roll is still saturated, they should be fine.
I have this same rig, in its entirety, and I cleaned up the leaking oil,
plugged the leaks around the terminals with varnish , and it plays fine.
These caps don't see much stress in this application.  The mineral oil is a
sticky mess, but not dangerous. If you have a case leak, a little JB weld or
solder will fix it after removing all traces of the mineral oil.

Welcome to the very small fraternity of people that own one of these gems.
(BTW, it is a motor lifeboat radio).  It has two 12V dynamotors in the
waterproof case, and the TX sits above the RX.  The cover fit over the front
and is dogged down like a hatch on a ship.  It is intended to be remotely
operated with a handset.

 

Regards,

 

Scott V. Johnson W7SVJ

5111 E. Sharon Dr.

Scottsdale, AZ 85254-3636

H (602) 953-5779

C (480) 550-2358

 <mailto:scottjohnson1 at cox.net> scottjohnson1 at cox.net

 <mailto:scott.johnson at ieee.org> scott.johnson at ieee.org

 

From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Ray Fantini
Sent: Thursday, June 2, 2016 5:55 AM
To: milsurplus <milsurplus at mailman.qth.net>; mrca at mailman.qth.net
Subject: [MRCA] Capacitor issues

 

So a 1936 USCG R-104 receiver followed me home from Dayton, it's very clean
and in no way modified and the intent is to build an external power supply
and case and have it working. One of the problems is that it uses two huge
square 4 mfd @400 volt capacitors in its power supply input along with a
filter choke and both of the capacitors have leaked a lot of oil out of the
can and all over the chassis. In the picture you can see one of the
offending capacitors that's been removed and cleaned up but I don't want to
put it back in being it will just leak more oil over time.  It still checks
good with only a small amount of leakage but would not trust it anyway. So
the big question is what's the best way to open this up and remove the guts
and substitute the innards with a modern capacitor? It appears that the
original can is soldered all around but I would prefer to keep the original
external appearance and finish being everything in the radio matches so
heating this up with a torch would be issues also don't know if the oil is
flammable. Maybe the answer is cutting around the base of the can but at
this point have no idea on how? maybe a dermal tool with a cutting wheel? Is
it possible that if the base of the can is heated with a torch that the
entire contents can be dropped out? Another option may be to solder up the
small hole on the outside of the capacitors can and install it back and keep
it original? Have lots of questions but no answers at this point. In the
past I would have just replaced the offending parts with modern ones but in
this case wanted to keep the receiver looking the same so that's the source
of the dilemma.

 

Ray F/KA3EKH

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