I am in the process of restoring a vintage EZGO Golf Cart and have came across a component I am unable to locate within the generic golf cart electrical diagram.
This varistor is from a 36 volt DC control circuit on a 1991 EZGO Marathon Golf cart, located between two terminals. I have researched the electrical diagram for this circuit and it does not show the varistor there. It may have come with the controller and the controller does not have an electrical breakdown diagram – just the connection leads.
I have researched online for a varistor with these markings: MDC Z750 40 with no luck. I am assuming, since the cart runs on six 6-volt batteries, the clamping voltage is 40 / it is a zinc oxide varistor and the manufacturer: MDC – Company Initials "Maida".
I am looking for a distributor that would sell a couple of these varistors or a recommendation for a suitable substitute that I can purchase. I contacted Maida directly and they responded with:
Unfortunately we do not offer parts for replacement purposes. We recommend that you follow up with Online Components.
Thank you for your time regarding this query. Photos attached.
Best Answer
You can use any varistor with a working voltage a few volts higher than the voltage of the line where it's connected. Check the voltage of the line or wire. If it's 36V, then search for a 38 to 45 working voltage varistor.
Attention: Not the clamping voltage which is far higher. The varistor starts to react gradually above the working voltage. Then clamps somewhere around 50% above the working voltage. Don't mix the two numbers. The working voltage is maximum at which you can use. A clamping voltage of 40V will be way too low for working with 36V. So I guess, 40V is the working voltage of this varistor.
Modern varistors will be several times stronger and better than the original one.