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Author Topic: Kenwood TS-140 Memory Channel/VFO Control knob "skips"  (Read 10613 times)
AL7MM
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Posts: 42




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« on: April 09, 2013, 12:37:22 PM »

The memory channel/VFO control knob (the rotary encoder on the left side of the front of the TS-140 "skips" when I turn it. Sometimes it doesn't change the memory channel when I turn the knob, and sometimes it jumps forward several channels. I'm guessing that there is some kind of dirt inside the encoder. Any suggestions on how to fix this control?
Thanks.

Mike, KL7MJ
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SWMAN
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« Reply #1 on: April 09, 2013, 01:46:12 PM »

 The encoder on my TS-570 does the exact same thing. I just learned to live with it. I have heard that it must be replaced and is not fixed by cleaning it. I just never really wanted to send it out for repairs. When the radio is off and I swish the knob back and forth very fast it seems to help for a while.   Good luck with it. 73  Jim W5JJG
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W8JX
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« Reply #2 on: April 09, 2013, 06:03:37 PM »

If it is acting up cleaning it with compressed air might help. If detents are sloppy or bushing is bad and shaft wobbles you need to replace it.  I have been lucky and never had one go bad on my rigs, yet anyway...
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K9YLI
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« Reply #3 on: April 10, 2013, 08:04:59 AM »

there are  curved  spring washers, that  you  might be able to add to the shaft to pre load the encoder in one direction to keep  down wobble if thats the problem..
i can get the  in local hardware store.
Midwest fastener   drawers..   paper drawers  in the  bolts aisle.

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SWMAN
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« Reply #4 on: April 10, 2013, 09:12:00 AM »

 On my 570 nothing wobbles or anything like that, everything is solid and tight, it just doesnt work as it should. Also cleaning and blowing compressed air on it doesnt work either. Kenwood told me that the only fix was to replace it. That was directly from them when I called.   
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W8JX
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« Reply #5 on: April 10, 2013, 12:32:00 PM »

It is a a optical encoder. If dirt gets in the right place it can block it. Problem is you need to dismantle unit some to get access to attempt to clean it. It is not that difficult to replace for anyone with some circuit repair experience. I have a 140 as a extra rig and encoder is fine but it has a bad set of band switching relays.
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N4ATS
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« Reply #6 on: April 10, 2013, 03:10:34 PM »

The fastest way to clean it , and it works 100% , chuck the encoder shaft in a cordless drill and let it rip for about 20 seconds....works EVERY time. I do it a lot to radios that come in with that issue , no need to take it apart...

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W8JX
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« Reply #7 on: April 10, 2013, 06:03:22 PM »

The fastest way to clean it , and it works 100% , chuck the encoder shaft in a cordless drill and let it rip for about 20 seconds....works EVERY time. I do it a lot to radios that come in with that issue , no need to take it apart...

You have been lucky because it could also "fix" encoder so it no longer works too.
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KE3WD
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« Reply #8 on: April 11, 2013, 06:00:25 AM »

..In which case its no harm nor foul to have tried the drill, which I also have used with both optical and the newer and cheaper point-contact encoders with quite a bit of success. 

If the drill kills it, you likely would have to replace the encoder anyway. 

These devices are still often misunderstood, I've encountered *many* hams and service technicians who assume that all of them are Optical Encoders. 

The reality is that, the newer the device, the more likely that the Encoder is a simple point-contact device, which, of course, can suffer from the same sort of problems found with any switch that does not handle current high enough to provide a cleaning action. 

If the Encoder is indeed of the Optical type, it can be troubleshot using the O'scope to determine if the problem isn't a simple calibration procedure, adjusting the tiny variable cap inside the encoder to restore X and Y to even.  This rather common problem is often the case when freezing occurs intermittently. 

I have found that it is worth looking up the part numbers found on the actual Encoder itself in order to determine which type you have presenting.  If it is a point-contact type, rotating the control shaft via the motorized drill can and does restore proper operation, presumably via the mechanical wiping action such provides.  Very few callbacks experienced from this trick.  Of course, in the case of callback, no more attempts to find the more economical cure, that encoder gets replaced at that point. 

The word of caution about using the hand drill to rotate the shaft is in order, though will likely be ignored by the heavy-handed and stiff-brained.  The object here is not to drill hole, nor is to attempt to *grind* anything.  Use of a drill with a speed-control trigger is highly advised, along with the constraint of common sense and mechanical wisdom when rotating that shaft.  Stay ON AXIS with the shaft.  Don't rev that drill to higher RPMs, keep it around the 200RPM rate or thereabouts.  And more is not better.  If after ten to twenty seconds of rotation, things don't improve, STOP with the drill, as this is a good indication that you are not dealing with point-contact encoder problem. 


73
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SWMAN
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« Reply #9 on: April 11, 2013, 07:08:16 AM »

ATS and WD, I tried the drill on my 570 and amazingly enough it worked, at least for now. But Kenwood told me that it was an optical encoder but it still worked as WD said it would only work on point contacts ? Good idea and an easy fix. By the way my 570 is 13 years old.   thanks and 73  Jim  W5JJG
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KE3WD
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« Reply #10 on: April 11, 2013, 12:23:43 PM »

The drill spin may clear a lightly clogged optical encoder, or they simply told you wrong as to what kind is in there.  Confusion abounds concerning these things. 

Hope it continues to work for you, saving money is always a good thing IMO.


73
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SWMAN
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« Reply #11 on: April 11, 2013, 12:54:27 PM »

 Thanks again !! Smiley  Smiley Smiley
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N4ATS
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« Reply #12 on: April 11, 2013, 05:29:13 PM »

Again , I do it frequently , it works very well , in fact , I have been doing it for years... It works with CONTACTS and ENCODERS as well , the constant speed wipes off the dirt or dust from the switch points or optics

Cheers
« Last Edit: April 11, 2013, 05:36:58 PM by N4ATS » Logged
AL7MM
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Posts: 42




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« Reply #13 on: April 12, 2013, 09:54:23 AM »

Thanks for all of the comments. I think I'll take that encoder for a spin and see how it goes!

73,
Mike, KL7MJ
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N4ATS
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« Reply #14 on: April 12, 2013, 10:01:38 AM »

Let us know how it goes....

Cheers
« Last Edit: April 12, 2013, 10:03:47 AM by N4ATS » Logged
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