Anyone still there?
 

Joe from Kokomo wrote:

On 11/21/2015 2:04 PM, analogdial wrote:

Been gone for a long while but decided to check in again. Got another
email address and another newsreader (Xpn).

Also got myself a Hallicrafters sx 100. Almost deaf, bad hum.

Freakin' snowy today. Time for indoor projects.

Frank Dresser

Congrats on the SX-100...nice radio and I always liked the engine turned
front panel.

You don't say how experienced of a radio repair person you are. The most
likely cause of the hum is a defective power supply filter capacitor;
"almost deaf" could be anything. If you have a way, check the tubes --
if you don't have access to a tube tester at a minimum try re-seating
all the tubes in their sockets. A schematic should be readily available
on the web. Check/replace the input coupling capacitor to the grid of
the final audio stage. A leaky cap here could damage/destroy the audio
output tube and/or the output transformer. Needless to say, be careful
around the high voltage; probably not fatal but more worrisome than the
9-12 VDC used by solid state radios.

Good luck and let us know how you make out.

Thanks, Joe. I've recapped about 10 Hallicrafters radios and I don't
think they're will be any surprises here. The fact that there's some
output and it tunes stations suggests the transformers are in
working order, which would otherwise be about the most difficult repair
to deal with.

My first guess for the reciever's deafness is one or more screen bypass
caps is very leaky. Doesn't really matter. I intend to replace all
the electrolytics, paper caps and check all the resistors. Haven't had
the time to open it up yet, but I expect it's full of those crummy pink
"tiny chief"s and even lousier black beauties.

The 50 kc IF alignment will be new to me.

Won't be getting to it for the next few days. I shoudln't procrastinate
too long, though. I run the risk that one of Brother Stair's doomsday
predictions will actually come true and I'll be heating my soldering
iron with the Fires of Hell.

Frank Dresser