Clark EC500:
EV-1 no scr hum

Ok, I've been working on an old Clark M: EC500-120 SN: E912-0008-6380. Unit has an Ev1 with extra large #1REC, #5REC etc. When you travel the contactors pull in but No scr hum and no travel. I have removed and tested the #1,#2,#5 RECs with a 12 volt battery and they will switch on and remain on until circuit is opened. I think they are good. I've tested #3,4 RECs (diodes) with a fluke meter and they conduct in one direction only. Resistance test are showing 750k ohms from componets to chassis. Isolated Battery by lifting and placing a sheet of plywood between battery and chassis Becouse I've heard of chassis voltages and some strange affects they can have. Have tested and inspected current sensor and all conections are good. Have raised drive tires put directional switch into fwd so fwd contactors close and then manually closed 1A contactor-drive wheels turn with 1A closed which tells me brushes etc. are good. Tested all Caps -good.
One thing that I have noticed is there is no cable or wire on T2.
Thanks ahead for any help anyone can give me.
  • Posted 7 Aug 2010 07:33
  • Discussion started by rrlift
  • Illinois, United States
Working so I can ride.

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