[R-390] PTO Problems

[Jon Schlegel]

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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