Help with Motor Start-Cap

[Lojix]

I'm working on a 'Miele Electronic 850 (Air Clean Plus)' vacuum cleaner, which has an AMETEK motor Model 119318-52 or 5079330 also labelled BC 30-5990 (240 volts 50/60 Hz)

The motor has stopped working (mostly). When left unpowered for several hours the motor will fire up for a few seconds, then go dead. I have removed the motor and assembly, cleaned and checked brushes. The wiring seems okay and there doesn't seem to be any signs of burned out electronics. My DMM checks show me 230V after the Hi/Lo switches.

For the above reasons, I think the cap attached to the motor may be the problem, but I'm not sure how to check for certain or at what points to test the power at the motor, to completely rule out burned/bad rotor windings.

[kaboom]

Re: Help with Motor Start-Cap

Universal motors do not use start or run capacitors.


Something's wrong with that triac ckt that varies the duty cycle of the AC feeding the motor. That's what the cap is related to- it's for RFI/EMI suppression. Noise is generated when that triac chops the current into that motor. Hence the cap, actually a multisection unit.

It could also be in the gate triggering/timing circuit for the triac.

[budm]

Re: Help with Motor Start-Cap

+1, that is X/Y safety cap for line noise filter.

[keeney123]

Re: Help with Motor Start-Cap

I do not know these motors, but would it have a centrifugal switch for any reason?

[stj]

Re: Help with Motor Start-Cap

no, but it would have a thermal cutout - usually self-resetting.

chances are the triac or diac are toast or some soldering is cracked.

[Lojix]

Re: Help with Motor Start-Cap

Thanks guys, I have a few leads to investigate further now. There really isn't too much circuitry on this motor, what would happen if I bypassed the board and gave the motor 240v directly?

[keeney123]

Re: Help with Motor Start-Cap

no, but it would have a thermal cutout - usually self-resetting.

chances are the triac or diac are toast or some soldering is cracked.

Thanks stj

[kaboom]

Re: Help with Motor Start-Cap

Thanks guys, I have a few leads to investigate further now. There really isn't too much circuitry on this motor, what would happen if I bypassed the board and gave the motor 240v directly?

The motor should run full-speed, just like in "lower end" vacuums w/o the speed control- aka the "anti curtain-shred" device. You'll have to clamp it somehow, it will try to escape with its starting torque!


Make sure you disconnect the motor from the board first. You don't want to backfeed anything. Also be sure to wire it as a series wound motor: half the field, armature via the brushes, then the other half of the field. You can run these on low DC voltages too, for testing. 12-24V DC works well.

Don't connect straight to the brushes or omit half the field, lest you pull a "RODALCO" or "Photonicinduction." Or a "kaboom."

[stj]

Re: Help with Motor Start-Cap

that's an interesting pair of foto's.
your thermal cutout is on the pcb, and what are those 2 microswitches for?

[Lojix]

Re: Help with Motor Start-Cap

Thanks for the helpful info

[Lojix]

Re: Help with Motor Start-Cap

that's an interesting pair of foto's.
your thermal cutout is on the pcb, and what are those 2 microswitches for?

These are the Hi/Lo speed control switches. 1 depressed is Lo, 2 depressed is Hi.

[Lojix]

Re: Help with Motor Start-Cap

I connected it directly to the main leads coming off the motor, without the board or multi-cap connected. First 12VDC, then 24VDC and nothing...

..and sorry for the quality of the images but I found some suspect wire in the windings around the rotor, could this be the culprit?

[stj]

Re: Help with Motor Start-Cap

that is not good - did you slip with a screwdriver, or did you get it like that?

[Lojix]

Re: Help with Motor Start-Cap

that is not good - did you slip with a screwdriver, or did you get it like that?

Nothing has been in there except my fingers. Exactly as I received it. Although I did move one strand of the copper so it could be seen easier in the picture... The screw driver would be the easy answer

Initially I wasn't sure if I was just looking at the ends of windings or broken strands. What makes me wonder about this though, is how did the motor run for a second on the first few attempts (now I cannot get it to even do that, just dead). Maybe partial contact and spinning loose?

...and although it would be a good 'first time project', I would rather avoid the arduous task of rewinding the rotor if I can

[Lojix]

Re: Help with Motor Start-Cap

I have also just noticed that two of the points on the commutator are bent up. There was no evidence of loose debris inside of the case when opening the unit, but it looks like something may have caused damaged to the motor while running.

[Lojix]

Re: Help with Motor Start-Cap

Thanks for all the input guys, I am pretty sure this thread has come to an end.

Motor apart, rotor out, I think something has hit the rotor whilst spinning, breaking the windings. I'm scratching my head as to how/what but from what I can see on the opposite side of the breaks, just below the two bent commutator points there is a gouge in one of the copper segments leading me to my conclusion.

[keeney123]

Re: Help with Motor Start-Cap

Thanks for all the input guys, I am pretty sure this thread has come to an end.

Motor apart, rotor out, I think something has hit the rotor whilst spinning, breaking the windings. I'm scratching my head as to how/what but from what I can see on the opposite side of the breaks, just below the two bent commutator points there is a gouge in one of the copper segments leading me to my conclusion.

I could be the front bearing is worn allowing the motor to not spin incorrectly causing the damage. If the motor was making noise before it went out that would also indicate the bearing being worn.