[R-390] Re: R-390 POWER SUPPLY

[Drew Papanek]

Clarence Lozano wrote:

>HELLO,I HAVE A R-390 POWER SUPPLY MAKES A HUMMING SOUND-NOT AC SOUND ,IS 
>THE >POWER SUPPLY REPAIRABLE WITH THIS TYPE OF PROBLEM?

Judging by the tone of his message the humming is pretty loud because he has 
to shout to be heard over it :o)

I "fixed" the transformer in my '67 EAC which had a loud mechanical hum.  I 
loosened the 6 captive green-headed screws holding the transformer to the 
mainframe each a couple of turns.  That reduced the acoustic coupling and 
provided a marked reduction in noise.

The noise was reduced further to an inaudible level when I used the radio 
sitting on a tabletop.  With the power transformer screws loosened I shoved 
a piece of padding (an old leather glove) under the transformer thus 
supporting its weight to the table and cushioning it.  It did not run hot 
that way.

Drew