Howard 437A

[David Franklin]

I thought that I would share my experience with the above receiver.

When I got the receiver it appeared to be complete.  All of the bypass
capacitors had been changed, judging from the capacitors used, I would
estimate 25 years ago. After initial checks for shorts and bad tubes,
I brought it up on my Variac.  The radio worked but had low sensitivity
on all bands and slight hum in the audio.  The radio was very dirty
inside and out and had nicotine stains and blue tape gum on the front
of the cabinet.

I washed the cabinet and the chassis with Simple Green and hosed it off.
I used a tooth brush on the hard to clean spots on the cabinet, avoiding
the painted on lettering. I then blew the water off and dried the radio
in the sun for 1 hour.  Then I put the chassis in the oven and manually
controlled the temperature keeping it between 150 and 180 degrees for
2 hours.

The radio cleaned up beautifully.  All of the stains came off the cabinet
and the copper chassis shined.  Next step was to re-string the dial cords
and replace the line cord with a 3 conductor for safety. I also tested the
filter capacitor with my capacitor checker and it checked good.

When I powered it up 2 weeks later for alignment, the filaments lit but at
first there as no sound in the audio.  After about 5 minutes the sound
came on as was as before.  Then while getting ready to connect the generator,
I noticed a wisp of smoke from under the chassis and pulled the plug.  The
smoke was comming from the power transformer.  I pulled all of the tubes
and checked again for shorts.  I powered it up without the tubes, the power
transformer again became very hot and sizzled.

My guess is that while cleaning the chassis that the cleaner and water
found its way into the transformer and broke down the shellac insulation
causing the transformer to short internally. I did not do anything to
protect it where the leads come out.  Will next time!

Thanks for listening.  I would appreciate any comments or experiences
from the learned group.

Dave Franklin

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