[R-390] Fix for ZERO ADJ.

[Barry]

I had the same/similar problem on one of my R390As.  I think someone had replaced the original plate/disk with a piece of sheet metal that didn't contact the clutch pins very well.  A replacement shaft fixed the problem.

Thanks,
Barry - N4BUQ

----- Original Message -----
> From: "Andy G8JAC via R-390" <r-390 at mailman.qth.net>
> To: "K PERALES" <kenperales at comcast.net>, r-390 at mailman.qth.net
> Sent: Friday, March 1, 2019 2:50:00 PM
> Subject: Re: [R-390] Fix for ZERO ADJ.
> 
> I just had to do mine.   The "stop" you feel is a flange on the inside of
> the knob contacting a lug held by the nut that holds the assembly to the
> front panel. The plate that you see is a pusher plate that operates the
> clutch which is behind the large gear.
> 
> The adjustment is detailed in the TM but I don't think that it was
> reproduced in the Y2K manual.
> Remove the knob from the Zero control.
> Wind in the shaft until you feel the plate on the end contact the clutch
> pins, then back off to give about 1/8 inch free play.
> Re-attach the knob in a position so that turning it anti-clockwise nearly
> hits the stop.
> Turning Clockwise should now release the clutch (so that you can move the
> VFO without moving the Veeder-Root counter). You may have to juggle the
> position of the knob on the shaft to obtain a good positive clutch release
> as the knob hits the stop lug.
> 
> Actually, I found that doing all this still didn't give me a good clutch
> release so the only solution was to drop the front panel down so as to see
> what was happening.
> The culprit was the disk on the end of the Zero adjust shaft was so loose
> that it was tipping over so that it failed to give even pressure on all
> three clutch pins so the clutch didn't disengage cleanly.
> The solution was to remove the shaft and disk and peen the end over so as to
> stop the disk wobbling.  Re-assemble, adjust as above, problem fixed.
> If yours is too far gone or broken, Fair Radio have them at $20.
> 
> Andy  G8JAC
> 
> 
> 
> Has there been anything written about repair of the ZERO ADJ., when it does
> not seem to release the clutch to zero the kHZ dial setting.  I am off from
> 1 to 3 kHZ over the full range of 0 to 32 MHz which is probably more than
> just the zero adjust but I cannot do even the basic adjustment on any
> calibration point from top to bottom.  Looking down inside the front panel,
> I can see shaft turning and as it gets close to the stop point turning
> clockwise, I can see what I assume is the clutch plate just barely moving.
> I have looked through many of the instruction manuals I have but seen
> nothing about repairing the ZERO ADJ.  I am guessing that someone out there
> has repaired this at some point.
> 
> 
> Ken Perales
> 
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