[Icom] rotary encoder

Tue, 27 Aug 2002 00:10:29 -0600

Hi,
O'scope is very handy when you work on IR choppers.
Dirt, grime build-up on the lens can reduce sensitivity some times.
Try Freon or pure Alcohol for cleaning.
73,
Tony, VE6CGX

Srikanth Bhat wrote:

>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.
>
>
>
>
>
>--- [email protected] 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,
>>[email protected]
>>Icom FAQ: http://www.qsl.net/icom/
>>    
>>
>
>
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>----
>Your Moderator: Dick Flanagan W6OLD, [email protected]
>Icom FAQ: http://www.qsl.net/icom/
>
>  
>

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