CMM 1200 won't start

fusilero

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Jun 9, 2013
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Hi;
I've got a CMM1200 cordless mower. After winter storage I left it to charge.

Full charge done, but it will not run. This is one of those odd models that does not use a key despite what all the manuals says it never came with one and has run for 3 summers without.
Checking continuity and battery charge:
Voltmeter to brushes with hand lever squeezed is zero
Battery has 24 volt charge
Continuity across Circuit breaker is ok (with a jumper to bypass, made no diff.)
Circuit breaker to brush to motor is ok
under the hood wiring is ok

brushes are worn but at least 1/8" visible

Any ideas what I should do next?
 

MowerMike

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benjames

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I had to replace my brushes today. I tested all of the switches, charger, etc. first. It's always the last thing you try because you quit after you find the problem ;-)

I had gotten some new brushes a couple of years ago but it turned out that they were fine at the time. Instead it was the circuit breaker.

Since I have some experience with the Black and Decker Mowers I will give a few hits for future reference. Most of these test require a cheap DMM.

Common Problems:
Batteries: Eventually they will charge less and less, I tend to replace mine before they are completely dead and then throw them into a UPS. An APC1250 will use these batteries. Batteries should always be purchased as a pair, do NOT replace just one. If you wait until the end of their life, you will notice that the 12V batteries will not hold 12 volts. Normally, good batteries will actually hold ~13 volts.
Circuit Breaker: check continuity across it while everything is off. It may pass and still be bad. You can hold a screwdriver across the terminals or jumper across it as a better test.
Brushes: If you put the DMM on Voltage and stick the leads on each side of the motor while trying to make the mower mow, you should see voltage go from 0 to around 26. In my case the contact had worn because the voltage was there but the motor didn't run.

Note of caution: This stuff is live. If you don't feel comfortable working with car batteries and circuits in your home then this is probably nothing for you to mess with.
 
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