Thanks Richard and Evan. I'll give more thought to the socket itself.
73,
Randy WB4SPB
----- Original Message -----
From: K9sqg
To: [email protected] ; [email protected] ; [email protected]
Sent: Thursday, February 09, 2012 10:35 PM
Subject: Re: [Drakelist] R4B audio distortion
Here is where a can of freeze spray can sometimes serve to help with
diagnostics. I serviced a Collins 516F2 power supply used with a KWM-2 and
found that the molded socket for one of the rectifiers had an internal short
that could not be seen from the outside.
-----Original Message-----
From: Richard Knoppow <[email protected]>
To: Randy WB4SPB <[email protected]>; drakelist <[email protected]>
Sent: Fri, Feb 10, 2012 12:27 am
Subject: Re: [Drakelist] R4B audio distortion
A look at the schematic indicates that you have hit all
the usual suspects. So, what else could cause the control
grid voltage to go positive? I wonder if the tube socket is
leaky. Even if the tube is on an extender it might be the
socket. It might be something on the surface of the socket
between pins. Pin 6 is the screen grid so leakage from that
could cause the problem. Check the socket for carbon tracks
or anything on the surface. Clean it thoroughly with dry
alcohol. Temperature might make a difference if there is
either a carbon track or something else there.
Perhaps far fetched but easy enough to do and worth a
try. If cleaning makes a difference but does not cure the
problem a new socket might be in order.
--
Richard Knoppow
Los Angeles
WB6KBL
[email protected]
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