i have had this same scenario a few times in the last 20 years, a couple of times, it was just a defective replacement board. I know this because i would go over the usual checks, check the motor field for grounds, check all wiring in the motor field circuit are tight, etc. then just end up replacing the board with a new one, and no further troubles. sometimes when it is intermittent, the board will be tested at the repair shop, and it will test ok. they then wrap it up and send it back out. another thing to maybe replace, is the small aluminum capacitor under the unit, the one that connects to the small choke. i think it is around 4 microfarads, this capacitor can cause troubles, it is cheap, and a great idea to replace on all of the 6010 drives. did you check the motor fields for grounds? you said you had 220k to ground, are you talking about the armature? the armature being grounded will not blow the fuse you are blowing, it will blow the main scr fuses. another tip , maybe not related to the fuse blowing, but will help with erratic problems, is to go through all of the terminals on the drive boards and make sure the are tight. good luck these drives can be a pain, but for their age, they do the job quite well. Did you replace just the motor field power unit, or did you also replace the field regulator board? If it was just the motor field power unit, then you might want to replace or swap the field regulator board with another car
Last edited by Vatorgator; 02/01/14 02:53 AM.