FMC Repair

FMC Wheel Balancer Repair:

Click on the pictures to zoom in.

Here are a few pictures of my friend's FMC 4100 wheel balancer.

I'm documenting the repairs we made to it. If you find this page useful, drop me an email.

This picture shows the machine after we completed the repairs.

1. The Brake was always stuck on. A soft hum came from the machine when the power was turned on.

(This picture shows the machine after we completed the repairs.)

2. There are two MOSFETs that control the relays located to the lower right. One relay controls the motor while the other relay controls the brake. The MOSFETS are controlled by a 7406.

We found the MOSFET that controls the brake relay was shorted and kept the relay closed all the time. Replacing the MOSFET did not solve the problem right away so we dug further.

Turns out the 7406 that controls the MOSFET was blown too. A quick trip to the junk board pile produced a 7406. We replaced that and then the brake system started working.

I substituted in a MOSFET I had on hand. two of the pins needed to be swapped but the part worked good.

After reassembly of the unit, we could not get a tire to balance!

After hours of study, I realized that the connectors on the main PCB are labeled (right to left) P2, P1, P3, P4, P5.

We had swapped P1 and P2 by accident.

Once we had all the connectors in properly, the machine worked great!

This is a picture of my friend reassembling the machine.

Here is a link to Steve Roger's web. Steve is a Sr. Project Engineer at Snap-On.

http://www.stevewrogers.com

I followed the links on his Resume page and got all sorts of good information about how the machine works from the patent office. (Very helpful!)

Thanks Steve.

Here are the links:

US Patent #	Patent Title

5054918	Light System for Measurement of Orientation and Physical Features of a Workpiece
5103595	Apparatus and Method for Reducing Vibration Characteristics in a Wheel Rim and Tire Assembly
5109715	Location Designator for Wheel Service Machines
5201224	Apparatus and Method for Sensing Unbalance Force and Location through Frequency Modulation
5208646	Wheel Alignment System
5220399	Wide Angle Wheel Alignment System
5307279	Self Diagnostic Wheel Balancer
5385045	Tire Changing and Balancing Machine
5592383	Wheel Aligner Cordless Communications Unit
5602733	Automotive Service Equipment Expert System
5734569	Computer interface board for electronic automotive vehicle service equipment
5999867	Computer interface board for electronic automotive vehicle service equipment
6085428	Hands free automotive service system
6282469	Computerized automotive service equipment using multipoint serial link data transmission protocols
6285932	Computerized automotive service system (Internet connected)
6405111	System and method for distributed computer automotive service equipment
6560516	Method for conducting vehicle diagnostic analyses using distributed structure
6564128	System and method for distributed computer automotive service equipment

Calibration procedures:

I got this of the web! It may be similar to your machine.

FMC 5800 calibration procedure

real easy'
1. turn balancer off then on again
2. push F then 1 then spin, display will read "cal slg"
3. take calibration slug off back of unit and screw into hole in backing plate
4. lower guard and spin wheel display will read cal 0
5. remove cal slug and respin display will read cal 600 d

I found this out on the web too!

http://www.agequipment.co.uk/
http://www.agequipment.co.uk/fmccal.html

FMC2500 cal procedure