Emglo AM78-HC4V motor stutter when nearing cut off

9 years 10 months ago #590 by popparottz
the motor in my Emglo AM78-HC4V starts fine, pumps well, but stutters a bit as it nears cut off pressure. Are there brushes in these motors? I replaced the pressure switch thinking the contacts were worn out but it still stutters. Any advice would be appreciated.

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9 years 10 months ago #591 by MTR-Admin
This could happen for a variety of reasons.

Make sure you're not running it on an extension cord.

The motor Reset Switch may need to be replaced.

The Pump/Motor Assy isn't aligned on the base properly (most likely this is it).
This is the case with these direct-drive units, if the unit isn't aligned on the frame properly it'll cause this.

Try doing this:

Remove the motor from the unit by removing the two 7/16" nuts under the motor. Remove the supply line. Remove the cover from the motor. Loosen the two 10mm nuts that hold the motor together. Put the motor on a flat kitchen style countertop. Twist both halves of the motor. Now, make sure that all 4 points of the motor frame touch the countertop and that there is NO rocking. Retighten the 2 10mm nuts being careful to not overtighten and breaking the aluminum frame. Reassemble the plastic housing, place back on the metal saddle and install supply line and 7/16" nuts.

- MTR

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9 years 9 months ago #595 by MTR-Admin
How old is the unit? And yes, there are Brushes in this particular Motor.

- MTR

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9 years 9 months ago #596 by popparottz
it's probably 25yrs old.

I tried your suggestions. I aligned the motor and pump, ran it with the reset switch out of the circuit, plugged it into an outlet 2 ft from the panel and it still stuttered although it seemed a little better. In taking the unit apart I found the insulation on the wiring was badly deteriorated so I fixed that...got a little better...found what appeared to be an arch spot on a paddle connector and wrapped it with electrical tape and it got a little better still. I've had it apart five times and I'm tired of working on it. When I get inspired again I'll replace the internal wiring and look at the brushes. How hard is it to get to the brushes?

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9 years 9 months ago #598 by MTR-Admin
Well with the age of the hand-carry we may want to look into the windings and armature. It is possible that this may be the cause of the symptoms.

- MTR

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