B20 Electrical

TGS · September 15, 2019, 01:47:14 PM

I'm having issues with my old B20 and I'm needing some help. When I first started today, the head would go down but not up. That's not exactly been an uncommon problem over the years. There is no question that my wire reel is worn out. When I disassembled it to clean the contacts most of them were worn through enough that they snapped off at the ends. I still get solenoids clicking when I press up or down on the switch, but the head doesn't move. I took the cover off of the terminal box and although I can get the solenoids to click by jumping from A-B or A-C, the head still doesn't move. I'm at a loss and was hoping someone could give me some ideas while I have time to work on it today.

Many thanks.

ladylake · September 15, 2019, 02:08:53 PM

A to E makes it go down. Make sure the bottom or upper limit switch isn't stuck or a broken wire.. First thing to eliminate the motor is to take some battery cables and jump from your pickup, positive on one wire negative on the other and switch them for the opposite direction right at the motor.. Steve

TGS · September 15, 2019, 04:48:00 PM

Ok, I wanted to come back and address what issues I found, in case someone has something similar in the future. When I took the inspection plates off of the electric motor I found that the galvanized mount that held the brushes was corroded and not allowing the brushes to move freely. I also found that connectors between the motor and power-in were melted. With ladylake's suggestion I cut these connections and wired the motor directly to 12v. It would cycle, but it was sluggish. I pulled the back plate off of the motor and found that it had a molded inset where the spindle bearing would sit. I found that my bearing on that spindle had seized and the entire bearing was turning inside of the molded inset. It also made me assume that the added electrical load and friction from that seized bearing is what caused the melting. I bored a 1/16" hole into the seal of the bearing and shot it with some PB blaster. A little persuasion with a pair of channel locks got the bearing loosened up. I kept shooting pb blaster and turning the bearing until rusty pb blaster stopped pouring out. I followed up with some spray white lithium into the same hole.

I reassembled the motor and found that I had regained downward movement of the head at a satisfactory speed; Up movement was still not working through the switch, though I could activate it with direct wire to 12v. The travel speed in the up direction still felt sluggish. I got down and started hitting the up switch and eventually it started moving up, but it was agonizingly slow.

That's where I'm at now. I wonder if the increased amp draw didn't smoke some of the windings or otherwise reduce the life of the motor.

ladylake · September 15, 2019, 05:01:00 PM

It could have smoked the winding but if your getting good up speed with booster cables hooked right to the motor it would be a bad solenoid or fried wire in the solenoid box or may just a bad connection. Sometimes just tapping on the solenoids with a hammer will make them work again. Steve

dchiapin · September 15, 2019, 05:38:54 PM

I had the same problem, except it was not happening all the time but intermittent. Mike at TK talked me through a bunch of trouble shooting. First his suspect was a bad solenoid. Yep replace the one he said was bad. Next day quit again. Bad up/down switch, replaced it. Next day same thing. Faulty motor, took it off and had it rebuilt, worked fine for a few days. Yep again it happened.
Since I had replaced the reel with a commercial reel I did not suspect that to be the problem. Wrong. The wires inside the cable had started to loose (for some reason) the insulation and where on occasion rubbing against another bare wire as the cable would go past each other.
Patched the uninsulated areas with electrical tape. Fixed it now for almost a year. Still on my have to list is replace the reel (again)

luap · September 16, 2019, 12:54:20 PM

Quote from: dchiapin on September 15, 2019, 05:38:54 PM
I had the same problem, except it was not happening all the time but intermittent. Mike at TK talked me through a bunch of trouble shooting. First his suspect was a bad solenoid. Yep replace the one he said was bad. Next day quit again. Bad up/down switch, replaced it. Next day same thing. Faulty motor, took it off and had it rebuilt, worked fine for a few days. Yep again it happened.
Since I had replaced the reel with a commercial reel I did not suspect that to be the problem. Wrong. The wires inside the cable had started to loose (for some reason) the insulation and where on occasion rubbing against another bare wire as the cable would go past each other.
Patched the uninsulated areas with electrical tape. Fixed it now for almost a year. Still on my have to list is replace the reel (again)

I have found liquid electric tape to be ideal for these situations. I have even used rubber windshield sealant with good results.