|03-17-2015, 08:19 PM||#1|
Not Yet Wild
Join Date: Mar 2015
MCOR - Very Poor Design!
Hi, I am new to the forum but have a good question for the experts on the MCOR. I have a 2008 DS IQ and I am having an issue with it when the pedal is all the way to the floor. When the pedal is pushed all the way down the golf cart stops going. At this point I have to release the pedal before it will start going again.
What I have read in these forums is that the MCOR could be bad. I also read the sticky about the MCOR being opened up and repaired. I have 20 years of electronic troubleshooting experience so figured I would tear it apart.
What I found blew me away! The switch works just fine on my unit like I expected. (The 2 pin connector) What I was expecting was resistance issues at near full throttle position. With a meter on 2 of the pins, and an appropriate screw driver used to turn the pot, the resistance varied from ~1.1k to ~6.6k but turning the pot anything past the 6.6k location it would go completely open. This should NEVER happen!
I have designed circuit boards and found that what is happening is the wiper of the pot is going past the conductive portion on the circuit board (hence open circuit) before the mechanical limitations of the rotation are reached. THIS SHOULD NEVER HAPPEN!!!
My question now is there a way to adjust the linkage in some way so that the pedal going to the floor never allows the pot to get to the area where the open occurs? This seems like such a HORRIBLE design to me so I don't want to order a new MCOR because the possibility of getting another one like this is VERY likely.
My understanding is that these should read between 0 and 5k so having a unit read 1k-6k (still 5k range) but off by 1k is a horrible design flaw.
Any suggestion from the experts? My two thoughts are glueing a block the appropriate thickness to the back of the pedal to prevent the pot from traveling too far or trying to get the linkage into the next slot so that it can never happen. Both ways will still not allow a 0-5k signal but at least it won't cut out. Suggestions or ideas? Do the latest version MCOR's actually all go from 0-5k? Which version do I probably have on a 2008 DS IQ?
Thanks in advance!
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|03-30-2015, 11:21 AM||#3|
Join Date: Sep 2012
Location: Charlotte, NC
Re: MCOR - Very Poor Design!
The MCOR has never been a 0-5kΩ potentiometer.
Your readings are correct, there is about a 1kΩ resistance on the "wiper" part of the MCOR (the big square pad on the PC board by the micro-switch).
It is impossible for a properly working MCOR to return an "open" reading, going outside the resistance track only means that the resistance would no longer increase.
You would need to dis-solder the 5 pins for the 2-pin and 3-pin connectors to access the tracks, there is probably some oxidation or gunk build up on the end of one of the tracks.
Unless You observed the same resistance anomaly with the MCOR installed, You may just be turning it past what the mechanical system would allow it to go and reaching an area not used and therefore oxidized.
Pressing the pedal all the way down and loosing power could be a sign of weak batteries as well.
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