[MRCA] Capacitor issues

[Ray Fantini]

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
scottjohnson1 at cox.net<mailto:scottjohnson1 at cox.net>
scott.johnson at ieee.org<mailto: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<mailto:milsurplus at mailman.qth.net>>; mrca at mailman.qth.net<mailto: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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