[R-390] r390/391 PS MOD 1

[Bill Hawkins]

Can't give you specifics, but I chased that problem once.

The unmodified supply has the center-tap of the high voltage winding
returned to metal ground on the PS chassis.

The modified version lifts this ground and connects it to the pin
in the PS connector that connects to (or used to connect to) the
28 VDC power line. It was used for a dynamoter PS, but the motor
was so noisy that the Signal Corps retracted the requirement and
so made the 28 VDC line unused. The line was used to ground the
HV center-tap to the metal of the main chassis, perhaps through
the old 28 VDC power fuse.

The 390 that I found this in had the chassis mod done with cold
solder and friction tape.

Regards,
Bill Hawkins


-----Original Message-----
From: Paul H. Anderson
Sent: Sunday, April 07, 2002 12:34 PM

Anyone know what the difference between a no mod PS and a MOD 1 PS on the
390 is?  Ground seems to be wired differently, at least.  The latest
manual I have is silent on the issue.