[R-390] Gear Train Removal

[Jim Whartenby]

Barry
What you have experienced was a know shortcoming of the original R-390 design and is mentioned in "Chapter 6.0 Recommendations" starting on page 79 of the Final Engineering Report.  Also mentioned are mechanical filters and tubes used that could have been upgraded if better tubes were available earlier in the design.  But at some point, the design work had to stop or it would have never left the engineering phase.  There is a point reached where the design is "Good Enough" aka GE.
Relax and take a breath, nothing you have done is fatal and all can be corrected.  Keep us informed.
JimLogic: Method used to arrive at the wrong conclusion, with confidence.  Murphy 

    On Wednesday, September 4, 2024 at 12:43:14 PM CDT, Jacques Fortin <jacques.f at videotron.ca> wrote:   

 Ah, also forgot to mention: the RF deck have to be re-installed in the frame
(see procedure chapter 59) BEFORE any re-alignment is attempted !

73, Jacques, VE2JFE in Montreal

Barry, some COMMENTS imbedded in your text below.

73, Jacques, VE2JFE in Montreal

Well, I don't quite know how it happened, but I can no longer get all the
cams properly aligned.  As I mentioned, I've removed the VR counter so
that's one point of reference that I no longer have.

AH, DON'T WORRY: I HAVE DONE THE SAME FEW YEARS AGO....

I had been rotating the MC change gear one click or two and then back and no
problem; however, I think I lost track of which way I had rotated it and now
I can't get back to where 2.000 would normally be displayed by the counter.

FOR THE MC POSITION, JUST RELY ON THE ROTATING DIAL OF THE SYNC XTAL OSC
THAT INDICATE ON WHICH MC POSITION THE SWITCHES ARE.

I'll mention that I've kept the Green Gear in place and, contrary to my
previous comment, that gear does indeed keep the MC and KC gears
synchronized and, given that, I don't know how they're no longer where I can
get them back in sync.

IT DEPEND ALSO IF YOU SET THE PROPER MECHANISM POSITION CORRECTLY BEFORE
REMOVING THE RF DECK.
READ THE CHAPTER 59 CAREFULLY AGAIN !!!
THEN, ROTATE THE KC SHAFT AND TRY FIRST TO ALIGN THE 8-16 MC CAM.
IF YOU ARE LUCKY, ALL THE OTHER ONES WILL ALIGN (IF THEY WERE ALIGNED
CORRECTLY PREVIOUSLY).
IF NOT, TRY A FULL TURN AROUND LEFT OR RIGHT (DEPENDING THAT YOU REMEMBER OR
NOT WHAT YOU HAVE DONE BEFORE).
OR... JUST TAKE THE PROPER ALIGNMENT OF THE 8-16 mc AS THE STARTING POINT
AND FOLLOW THE FULL CAMS RE-ALIGNMENT PROCEDURE CAREFULLY !

According to the manual, as part of the complete gear teardown and rebuild
(which I still have not decided to do), one is supposed to be able to rotate
the MC gear CW (which I presume is taken to mean "CW as viewed from the
rear"), until it hits a stop point and then, back up to the nearest notch
which should correspond to 0.000.  My presumption is that if I back off to
the 3rd click, that should correspond to 2.XXX and rotating the KC shaft
should eventually get the gears (and cams) in the 2.000 position.

I found that there is something that causes a "stop" at full CW and full
CCW.  I think that stop is happening as a function of the Geneva mechanism
and not the 10-turn stops (which aren't engaged when the RF deck is
removed); however, CW or CCW still won't let me get the gears/cams in their
proper setting and am wondering if I'm now truly "stuck".

Any help is appreciated.

Additionally, to avoid getting the transformers' cores wet, I'm removing the
slug racks and transformers while cleaning the gears and, right off, I found
that one of the slugs (for Z2223) was broken.  I'm sure that didn't help
performance any.  I have it CA glued back together so that should help when
I get this all reassembled.

Thanks again,
Barry - N4BUQ

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