DC motor troubleshooting

Yep. I will check all that tomorrow.

Lloyd, I did read his post, several times in fact. I did not fire a volley, one shot only, trying to hit the target.....

I am not trying to cause problems here, just trying to help where I think I can as I do have experience in things DC albeit in the forklift trade.

If I'm reading it correctly his motor sounds like any other dc motor that is not a permanent magnet motor. It has a field winding F1 F2 and an armature with a commutator that brushs ride on A1 A2.

The fact that it only has three leads is what confuses me.

Either way supply voltage out the controller + or - will enter the armature go through the fields and then back to the controller causing the armature to rotate. Pulse Width Modulation will control the speed and torque of said motor.

If by any chance this is a separately excited motor, the field cables are normally smaller then the armature cables. The fields and armature would each be supplied voltage via the controller which would to my knowledge take four motor leads. Seeing as this has ( THREE ) motor leads with one connected to both A2 and F2 the other two must go to A1 and F1. The single wire to A2 F2 would be the positive in, according to Iggy 50 volts and the other two would be would be pulsed negatve from the controller but since Iggy said it was a SIMPLE DC DRIVE I didn't think it was that kind of motor.

The fact that he has fifty volts at A2 F2 out to A1 and also F1 would suggest that the motor is ok.

My thoughts are that the drive is bad. To test the motor I would hook up a car battery to it, POSITVE lead to A1 NEGATIVE lead to F1 Install a jumper to connect A2 and F2 together and will turn one direction, reverse the power cables on A1 and F1 and it will turn the other direction although slower then at 50 volts.

Is the X and Y travel on this thing fed through one or separate controller? That would seem to be a good way of checking where the problem lies

You are assuming it is a series traction motor - which would be useless on a feed screw because it has no speed regulation. This is almost CERTAINLY a shunt motor - with variable field current to control the speed - quite accurately in fact - independent of load. Your fork lift experience is helpfull as far as it goes, but it doesn't go far enough.

jeff fired this volley in news: snipped-for-privacy@4ax.com:

No, I think you mis-read that. He said there was 50V across the field, and ALSO 50V across the armature.

It's entirely possible for a drive to supply a steady-state voltage to the field, and vary the armature voltage -- even to the point of inverting the polarity of that second one.

Not all DC drives are "simple". I have a golf cart (personally) that accepts DC from the battery into the (electronic) drive, and supplies +-V (plus OR minus polarity) to the motor armature at full battery voltage (without relays), and pulse-width-modulates the field at a single polarity.

That provides both directions and variable speed without switches or relays... from a 'single' 36V storage battery.

LLoyd

LLoyd

You are correct, I was assuming and know better. Thank you

He said there was 50V across the field, and ALSO 50V across the armature.

Shit I should have read it one more time, I missed across.... open circuit.... Sorry

Likely, but you would have 50 volts across either one, open circuit or not.

Actually -- the *motor* itself has your four terminals/wires, A1, A2, F1 and F2.

The wiring from the driver/power-supply/WhatEverYouWantToCallIt is three wires. One of them goes to one Armature terminal, one goes to one Field terminal, and the third wire goes to both the remaining Armature and Field terimnals. They're saving one wire, and tying together one end of the Field and one end of the Armature power, a common low voltage point for both.

Perhaps the currents are too high in the ones which you work on to allow that sharing of leads. But his is not nearly that high a power, and perhaps the distance from the motor to the supply is long enough so it is worth while doing it that way.

Good Luck, DoN.