[Icom] rotary encoder

[icom@mailman.qth.net]

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