[R-390] PTO Problems

Sun Nov 4 16:07:19 EST 2007

Hi all,

This PTO may be in pretty poor shape.  After 
cleaning, the fiber roller's staked in shaft 
broke off with only a reasonably gentle wiggle to 
see if there was any play to allow things to get 
going again.  I should be able to fix it if I can 
find suitable non-magnetic odds and ends to use to make a new shaft.

There is what appears to be a stainless "roller" 
that follows the opposite side of the corrector 
stack.  Is this "roller" supposed to spin or not as it follows the stack?

Also, a few weeks ago I recall some list members 
working out some backlash problems.  I can now 
see that I can see numerous spots where backlash 
could creep in that might need adjustment.

Regards,
Jon

At 08:10 PM 11/3/2007 -0700, you wrote:
>Jon,
>
>Don't ask me how I know, but a spring from a ball point pen will work.
>Granted it is a compression spring, with a little work; cut to length and a
>hook bent into each end you are in business.
>
>Later, after I got my PTO back together and the endpoints set I found an
>extension spring at a local hardware store. It is still in a little box just
>in case I ever get bored and want to open the PTO again. I'd rather poke
>needles in my eye! But I'm ready for the next go around.
>
>Craig,
>
>-----Original Message-----
>From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
>On Behalf Of Jon Schlegel
>Sent: Saturday, November 03, 2007 7:57 PM
>To: r-390 at mailman.qth.net
>Subject: RE: [R-390] PTO Problems
>
>Craig,
>
>I'd say your memory is pretty good because it's
>just as you describe.  The entire arm thing is so
>corroded that I missed the fact that there is
>that smaller secondary arm that pivots on the
>main arm.  I can just make out the spring
>holes.  As you suggested, the spring has long
>turned into some other iron compound and is no
>longer with us.  Guess I'll have to play
>Goldilocks and find a spring that's just right.
>
>Thanks very much, Craig.  That solves that problem.
>
>Jon
>
>
>At 07:33 PM 11/3/2007 -0700, you wrote:
> >Jon,
> >
> >Going from memory here, I should of taken digital pictures, shame on me.
> >Anyway, there should be a small spring pulling those two arms together
> >pinching the corrector stack, (where the rollers, wipers, etc., are
> >attached). I think mine had one rubber roller, it did have a shaft and
> >rolled across the corrector stack. The other arm might have had something
> >more like a wiper that slid across the corrector stack.
> >
> >In any event, search for two small holes on the arms where the spring was
> >attached. The spring might of rusted into tiny flakes long ago! A little
> >penetrating oil, WD-40 used sparingly where the two arms pivot should free
> >things up where the roller and wiper can function.
> >
> >A trip to the hardware store might be in your future searching for a tiny
> >extension spring.
> >
> >Craig,
> >
> >-----Original Message-----
> >From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
> >On Behalf Of Jon Schlegel
> >Sent: Saturday, November 03, 2007 6:47 PM
> >To: r-390 at mailman.qth.net
> >Subject: Re: [R-390] PTO Problems
> >
> >Hi all,
> >
> >I've discovered another possible problem with
> >this (Motorola) PTO regarding the corrector stack
> >follower.  There appear to be two rollers that
> >follow the compensator stack (both are now
> >frozen).  The one normal looking roller has what
> >appears to be a fiber bushing, grayish tan in
> >color.  A domed cap appears to retain the bushing
> >on its shaft.  I can see vertical striations
> >around the circumference of the fiber bushing
> >which would tend to indicate that this bushing
> >did at one time roll as it followed the corrector stack.
> >
> >The other roller has neither a domed retaining
> >cap nor a fiber bushing.  All that appears to be
> >present is a stainless roller.  I found no
> >evidence of these seemingly missing parts when I opened the PTO.
> >
> >When the follower arm is at a position on the
> >corrector stack where it's ramping up or down,
> >there does not seem to be any radial play of the
> >arm on the lead screw.  When the arm is dialed to
> >a spot where the corrector stack is flat meaning
> >no change in cam height, there is about 10 or 15
> >thousandths radial play of the arm.
> >
> >Is this play normal?  Are there parts missing?  I
> >can only imagine that the play I'm seeing could
> >cause some nasty hysteresis in the tuning of the receiver.
> >
> >Regards,
> >Jon
> >
> >
> >
> >At 01:56 AM 11/3/2007 -0400, you wrote:
> > >Renée,
> > >
> > >Well it's a consensus then.  When I opened it up
> > >I finally understood the corrector stack that I
> > >hear people talk about.  Guess it's time warm up
> > >the counter and generate some more gray hair.
> > >
> > >Jon,
> > >WA3MVM
> > >
> > >At 10:44 PM 11/2/2007 -0700, you wrote:
> > >>Jon-
> > >>May I be next thursdays Trash?
> > >>actually it is most likely completely repairable.
> > >>Renée, K6FSB
> > >>
> > >>Jon Schlegel wrote:
> > >>>Hi all,
> > >>>
> > >>>The PTO shaft seemed way too stiff so I opened
> > >>>it up and found this amazing colony of
> > >>>crystalline entities growing all over
> > >>>inside.  It's a real mess.  It looks like it
> > >>>had a LOT of moisture in it at one time but
> > >>>the rest of the receiver doesn't really show
> > >>>signs of water problems.  Nevertheless the PTO
> > >>>looks original to the receiver (both Motorola).
> > >>>
> > >>>Should some kind of repair attempt be made or
> > >>>should go out with next Thursday's trash?  I
> > >>>have an interesting photo but I suppose that
> > >>>would be inappropriate for the list.
> > >>>
> > >>>Regards,
> > >>>Jon
> > >>>
> > >>>
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