[MRCA] Capacitor issues

Thu Jun 2 10:37:44 EDT 2016

Neither Scott of I suggested draining the rest of the oil. Just seal it up
properly. I am 71 now and when I was a kid I used to take caps apart for
fun. Used to swim in PCBs. Who needed gloves. Had asbestos lined bench also.
Same where I worked as a tech in the late 50's and 60's. Still here, HI. 73
- Mike 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell, NJ, 07731

732-886-5960 

From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Ray Fantini
Sent: Thursday, June 02, 2016 9:31 AM
To: Mike Feher; 'Scott Johnson'; 'mrca'
Subject: Re: [MRCA] Capacitor issues

Think if I tried to drain remaining oil it will never all drain and always
have something that's a lot like a cross between motor oil and tar that will
be leaking out so if anything am inclined to do complete replacement of
innards with the option of cleaning out shell. The amount that has leaked is
only a small fraction of a once but a little bit of that crap goes a long
way. The thing about cleaning and sealing is the capacitor is eighty years
old and in addition to the small amount of leakage is it possible that some
moisture has entered over the last eighty years and contaminated the
capacitor? I may try connecting one up to two or three hundred volts and
seeing if it develops more leakage or internal heat. Don't think this radio
has had any voltage applied to it in decades. The capacitors like everything
else in the receiver or RCA manufacture so what the status of PCB use was in
1936 is a good question. Years ago had to do PCB removal on broadcast
transmitter and that was a big deal where you received a five gallon can
along with apron and gloves and deposited the offending capacitors into the
can then also the protective clothing and everything else into the can and
sealed it and sent it off for proper disposal, and that was for capacitors
that were not leaking. Between radium paint and PCB oil wonder how many of
us are running potential toxic superfund sites?

Ray F/KA3EKH

From: Mike Feher [mailto:n4fs at eozinc.com] 
Sent: Thursday, June 02, 2016 10:20 AM
To: 'Scott Johnson'; Ray Fantini; 'mrca'
Subject: RE: [MRCA] Capacitor issues

That was going to be my answer as soon as your post came up, but, I figured
you were going to be saturated with replies, so decided not to bother. 73 -
Mike 

Mike B. Feher, N4FS

89 Arnold Blvd.

Howell, NJ, 07731

732-886-5960 

From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of Scott Johnson
Sent: Thursday, June 02, 2016 9:16 AM
To: 'Ray Fantini'; 'mrca'
Subject: Re: [MRCA] Capacitor issues

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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