[Icom] rotary encoder

[Srikanth Bhat]

Thanks a lot Al,

That was very descriptive indeed, and I sure do
appreciate the effort and time you took. Infact I
tried an elaborate cleaning exercise some time ago,
without much luck. Maybe I have to tinker around with
the IR source/transmitters a bit - which is something
i hadnt tried.

I gather from HRO that this encoder unit is no longer
manufactured by Icom, but the replacement available is
a modified version of the one that is used in the 718.
You need to mention that its for the 735 while
ordering - The part number is 91509051, costing $90. I
got this info from YL Janet of HRO Anaheim, CA.

Best 73
de Sri, VU2SBJ, India.





--- awaschka@bellsouth.net wrote:
> I had a similar problem.  Icom says the replacement
> part is no longer available.
> They suggested taking it apart and cleaning it.  You
> can do this without opening the radio up. Just
> remove the main tuning knob. Then you can use a
> vacuum cleaner or some compressed dry air to clean
> out any dust that may have accumulated.
> Cleaning didn't fix my problem, so I had to look
> further.
> The encoder is made with two LED-photodiode pairs,
> one at about 10 o'clock and one at about 2 o'clock,
> that look through a two-part grating. 
> One part is fixed and mounted with two screws.  The
> other part is mounted to the shaft.  You can remove
> the screws holding the encoder to the front panel. 
> Two more small screws remove the PCB with the
> LED-photodiode pairs on it. Then you can remove the
> mechanical part of the encoder from the radio and
> leave the PCB hanging.  Look through the slot where
> the PCB was and observe the fixed part of the
> grating.  Mine was loose and formed an "S-curve"
> from one mounting screw to the other and would "pop"
> so that it was close to the rotary disc on the right
> side and "pop" back to be close on the left side. 
> Also observe the condition of the slots in the fixed
> and rotary parts.  This is where dust or lint will
> kill you.  The way it works (hold it up to a light
> source and look through the grating as you slowly
> turn the shaft) is that when rotating clockwise, the
> left side (I think) blinks first, then the right. 
> When turning the other way the order is reversed.  
> 
> If your fixed grating is loose, you can remove a
> c-clip on the back to remove the shaft.  Place the
> parts carefully on the desk or draw a picture so you
> can get it back together the same way you took it
> apart.  BE CAREFUL with the encoder disc and the
> fixed encoder.  They are fragile.  Then you get
> access to the mounting screws.  Loosen them both. 
> Push the grating to the right and tighten the right
> screw.  Then push it to the left and tighten the
> left screw.  The idea is to get the grating tight
> and straight.
>  Put it all back together and if you have the same
> luck I did, it will work properly.  Oddly, mine was
> still strange right after I put it back together. 
> After the parts settled together (an hour or so) it
> started working fine and has had no problem since.
> 
> If this doesn't work, there are encoders available
> (look on the web).  They aren't exact replacements,
> but I think one could be made to fit.  That was my
> backup plan, but I didn't need it.  I think you need
> a 250 pulses per revolution encoder.  Just count the
> number of changes in the least significant figure of
> the dial in one rotation and multiply by ten.
> 
> 
> 
> Good Luck,
> 
> Al K5TAN
> 
> 
> 
>   
> 
> 
> ----
> Your Moderator: Dick Flanagan W6OLD,
> icom-owner@mailman.qth.net
> Icom FAQ: http://www.qsl.net/icom/


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