Re: {Collins} 75S-3 S-meter Issue

Check R-57 the RF gain adjust potentiometer.  It is a 1K in series to ground from the cathode of V-6.
Glen, K9STH 

    On Sunday, August 18, 2019, 07:09:14 PM CDT, Chuck Curran via Collins <collins@xxxxxxxxxxxxx> wrote:  
 Hello the Group:

I received a S-Line for repair, all items not having been on the air for 20
years.  I started to repair the 75S-3 receiver for the owner, and was
pleased with the success, after replacing electrolytic's and the Sangamo
coupling caps.  PTO was messed up, as far as end stops and pointer being
vertical, but that was resolved too.  Alignment followed, with great
success, all ceramic trimmers were NOT frozen, a real surprise!

OK, now on to the issue.  S-meter was jumping all over, the zero pot was
junk.  Found a suitable replacement and installed it after lunch today.
That totally cured the jumping problem, when trying to set zero.  However,
I now see that the S-meter response is way high.  The calibrator signal
PINS the S-meter, without a problem.  I checked pin voltages on V6 and V7,
both were within spec.

All on the air signals I have listened to are also WAY high, crazy high
S-meter levels.

All tubes were checked on my Hickok 752, three weak tubes were replaced,
V3, V8, and V11.  Supply voltages are to spec.

So, any suggestions on where to go next?

Thank You in advance,

Chuck W9KR
*** You are subscribed to Collins as k9sth@xxxxxxxxxxxxx. If you wish to unsubscribe, or modify your preferences please visit ***

This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.