View Single Post
  #1   Report Post  
Old November 3rd 09, 02:33 AM posted to rec.radio.amateur.boatanchors
Engineer[_2_] Engineer[_2_] is offline
external usenet poster
 
First recorded activity by RadioBanter: Jul 2007
Posts: 41
Default Capacitor failure report

Hi, Vacuumlanders (boat division :-) )
I don't spend much of my time on boatanchors but this may be of
interest.
While restoring a Bendix RA 10DB receiver as part of a CASM, Toronto,
Lancaster bomber restoration project, see:
http://casmuseum.org/avro_683_lancaster_x.shtml
one of the decoupling caps failed spectacularly. It was C54. First
there was a smell as plate decoupling resistor R15 (1000 ohms)
overheated, then smoke (I think from from R15 paint), then C54 got
very hot and oozed a white bubbling substance... B+ had dropped from
221 VDC to 183 VDC... hit the off-switch fast! Fortunately, no
dynamotor damage. This unissued, NOS Bendix radio had earlier been
powered for about a hour or so in several check-out sessions without
any trouble.
The cap is one of several marked "Solar TYPE [blank] MADE IN USA .1
MFD 400 VOLTS DC GRD (at one end)" It has a rectangular brown
plastic case (bakelite?), about 1 3/8 x 5/8 x 5/16 inches in size.
There are several of these in the set, some but not all are under B+.
I'll be watching them. I presume this is a mica cap but others may
know better.
Just one small event in a myriad of restoration experiences, but
factual data... not just an anecdote!
Cheers,
Roger