[Milsurplus] PCB'S??

[WA5CAB at cs.com]

Comments below are my opinion, based upon some recent research and half a 
century of experience.

They may be (PCB containing).  Transformer oil containing PCB's first 
appeared in the 1930's.  Don't dispose of the oil by dumping it in your back yard 
(don't do that with used engine oil, either - it'll kill the grass).  Don't 
clean your hands with your tongue.  I would suggest wearing disposable 
nytril gloves AKA surgical gloves (they are dirt cheap) while opening the cans.  
But I'd do that even if I knew that the oil was straight mineral oil.  Use 
a plastic or metal pan to catch the oil.  Whether the oil contains PCB's or 
not, it won't do your workbench any good to get soaked with it.  For one 
thing, manuals or papers stacked on it later will get oil soaked.  Don't 
deliberately breath the smoke or fumes you may get when desoldering or soldering 
(applies equally well to any soldering operations).  If you don't normally 
wear glasses, wear safety glasses, but don't wear a face shield.  It may trap 
fumes.

In brief, treat it the same as you should if you knew it did not contain 
PCB's.  The specific dangers pertaining to PCB's have to do with the tens of 
millions of gallons of the stuff produced over roughly half a century.  Not 
to the few fluid ounces contained in the capacitors of one or a few vintage 
radios.

As a practical matter, if the rubber seals have gone sticky and gooey, the 
capacitors will probably start leaking oil as the interior of the radio gets 
hot from operation and the residual air in the cans heats up and expands.  
Which will make a mess, PCB's or no.  So if the seals are bad, you need to 
drain the oil at least.  Considering that you will probably have to remove 
all the cans in order to do that, it would probably be wise to go ahead and 
rebuild them (replace the original capacitors in the cans with new ones).  My 
preference for this are metalized polyester axial lead tubular capacitors.  
I stock only the 630 volt rated ones, having found that they will fit 
physically in place of the oiled paper originals in virtually all of the oil 
filled canned capacitors in the WW-II and Korean War vintage gear up to 600 volt 
rated.



In a message dated 10/3/2009 9:22:27 PM Central Daylight Time, 
bavarianradio at comcast.net writes: 
> Hello all, I'm beginning a restoration of an RBA-3 WWII receiver. It 
> appears that ALL of the rubber grommets on the oil filled bathtub capacitors 
> have failed. They appear red in color and are sticky and gooey.  I have been 
> careful not to touch these (too much anyway) and I wash thouroughly after 
> working on this radio.  The question is....  are these caps filled with 
> PCB's?  and if so what precautions should I be taking?  On a different note, 
> remarkably the radio was working before I took it apart. I was going to clean 
> all the switches and pots and touch up the alignment, with recapping 
> occurring after a performance evaluation. When I saw the condition of the seals, 
> I thought I had better recap first.  I have a RBM-5 set here also that 
> plays with the original caps and performs nicely! ( I don't leave the room 
> with it on, however)  The caps in the RBM look like new compared to these.  
> Any thoughts?? 73's Ross

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480