[Milsurplus] Navy REP Morale Receiver Repair

[David Stinson]

(Permission granted to republish or otherwise use the
  text and photos in this posting with proper attribution.)

Recently set to work on a Navy REP Morale receiver
and thought I'd pass along some tips.

The set already had some "fiddling" done; the multi-section filter
cap is missing as well as one "SPARE" tube socket.
Some dingbat drilled two small holes in the front for phone jacks-
think I'll make a "Buy More Bonds!" sticker to hide them ;-)
It had a thick layer of smoke residue- so bad the thing was
uniformly brown.  Must have started life in a bar.
The audio output transformer and the speaker were both bad.

First tackled the smoke film. Mild soap and water did not touch it.
I removed the front panel, dial lens, speaker covers and nomen plates.
Used this "foaming cleanser" product to cut the nasty stuff:
http://c1.soap.com/images/products/p/hdl/hdl-023_1z.jpg
followed by extended rinsing.
Be careful around the silk-screened lettering on the panel.
They held-up OK under this product for a short time,
but leaving it on for too long will erase them.  I used a toothbrush
to scrub the panel and GENTLY around the letter, rinsing it
right off as soon as the lettering area was acceptable.
Never use such stuff without removing screws, plates etc. first
and rinsing well, unless you'll like green corrosion in a few years.
While the finish still has some scuffs and stains,
it's much better than "smoke brown:"
http://home.netcom.com/~arc5/REP/REPfront.jpg
http://home.netcom.com/~arc5/REP/REPnomen.jpg
http://home.netcom.com/~arc5/REP/REPrearplt.jpg

A cleaning caution:  Inside the big cover there are three paper labels-
schematic/parts list/alignment procedure, above-chassis parts placement
and below-chassis parts placement.  These appear to be glued and
shiny-coated, so one would think they'd be safe if gotten a little wet.
Wrong.
While rinsing, I got the schematic wet and it pulled-away from the case.
With it peeling and wrinkling, I thought I'd better go ahead and soak it 
off,
make copies and preserve it before re-gluing.
Well... the paper on which the diagram is printed is the old
 "clay-coated" type, which is why it looked shiny.
A lot of the diagram and ink washed right off the surface of the print.
ARG!!

Thank The Almighty I got photos of the labels before the cleaning
and have uploaded them.  I'll leave it to people more talented than I
to "stitch" them together (some files 600k).

http://home.netcom.com/~arc5/REP/REPdiagLFT.jpg
http://home.netcom.com/~arc5/REP/REPdiagRT.jpg
http://home.netcom.com/~arc5/REP/REPparts1.jpg
http://home.netcom.com/~arc5/REP/REPparts2.jpg
http://home.netcom.com/~arc5/REP/REPpartsmap.jpg
http://home.netcom.com/~arc5/REP/REPlayout.jpg
http://home.netcom.com/~arc5/REP/REPalign.jpg

The REP is mechanically sturdy but there's nothing special about
the circuit.  It's a straight-forward consumer-grade superhet.
http://home.netcom.com/~arc5/REP/REPinside.jpg
http://home.netcom.com/~arc5/REP/REPunder.jpg

The tube sockets are rivited in place.  On this one,
all the active tube sockets have been soldered to the chassis to
avoid ground intermits.  Don't know if it was built this way
or if it was done later.  If yours doesn't have this, I recommend it.

As one of our members noted- the biggest problem is the
pile of mica capacitors.  Nearly all of them were leaky,
showing symptoms of silver migration.   The larger, square
caps all tested "good,"  but most of the smaller, rectangular
ones were bad.  This includes the four 100 pFd caps across
the IF transformer coils.  Take care in changing those as the
wire from the transformer coils is hair-fine.  The leads on the
old mica caps inside the IFs are formed with a "loop" for
soldering the IF transformer leads.  I used thin nippers
to cut the leads right at the cap body and installed the new
silver micas using these "loops" as terminal points.
All but a couple of the sealed Sprague axial oil caps tested "good."

*A caution on replacing the RF circuit micas:*
Do not attempt to unsolder the micas mounted on
the bandswitch.  Clip the leads and "tack-in" a replacement.
The switch is 70 years old and fragile.  If you attempt to
unsolder and unwrap, you WILL break it.  Fair warning.

I pulled the bad audio output transformer and removed the
eyelets holding the ends of the case, removing the top and
exposing the tar-potted innerds.   Clamped it with Visegrips
and hung them so I could carefully heat the case with a propane torch.
The gloop eventually slid out and didn't even mess-up the paint.
Removed the bad tranny guts and dissolved the tar on the
connection board/base with Ronson lighter fluid and a brush.
Installed a "Utah" 5000-to-4 Ohm output transformer inside
the case and closed it back up.
I don't have the "correct" 6-inch speaker, so mounted a temporary
4-inch replacement until I can locate the right one.
Replaced a bad mixer tube and the dim 6E5 eye tube.

Temporarily installed a little 12-volt "bucking" transformer under the
chassis (that tape-wrapped black thing near the power tranny)
which bucked the line voltage down to 108 Volts, but 200 mA
must not be enought "umph" because it gets pretty warm.
I'll find a bigger, better one and mount it properly.
As another member noted, the Crosley power transformer is
barely adequate.  At 108 volts, it's hotter than I think a power
tranny should run.  At 120 volts, it's cooking-off for sure.
So a proper bucking tranny seems a necessity.

The alignment was touchy but straight-forward.
Performs well and sounds good for a consumer-grade set.
One niggling problem: when switched to Shortwave Band 2
while the set is still "cold" and tuned to the low end,
the Mixer stage breaks into a parasitic oscillation and blocks the set.
Tuning up the band and switching between 1-2 stops the oscillation
and it goes away after a few minutes operation.
Everything in the stage checks OK, so I'm wondering
 if it's a lead-dress issue or just a "feature" of the set ;-).

Thanks for reading,
73 DE Dave AB5S