1993 Milwaukee Super Sawzall Cat No. 6527 carbon brush replacement

[Mr. Haney]

The unit was leaking voltage. It gave a "tingly" feeling when touching the metal motor housing. I was told the shellac on the 120v field had probably burnt off and I'd need to replace it, which I haven't ruled out yet although the windings look OK to me, nice and shiny like new , at least what's presently visible. However, the commutator is burnt and I'm going to clean it.

So far, I've found a broken carbon brush which requires replacement as well as perhaps the brush holder assembly (the broken carbon brush fell into the "well" on top of the ball bearing where the armature seats). I was also advised to replace the brush springs while I'm at it just to be safe. I broke the unit down from the front and got stuck at the motor housing.

Do I need to proceed from the front end, which would entail pulling out the field, etc.., or could I break it down from the handle side? The items in question are #'s 26 , 27 & 32 in the schematic provided in the link below.

Any advice on this subject is appreciated. Thanks.

http://www.ereplacementparts.com/images/milwaukee/6527_(SER_774B).pdf

 

[duke37]

I know nothing about your saw so what I say is generic only.

It looks as if Pin9 holds the handle end on.
The saw is povided with three wires, two will be power and the third earth (ground). If the earth is connected, then you should not get a tingle. Make sure your power supply is up to specification and that you are supplying the saw through a tested earth leakage trip.

Carbon dust is conductive and must be cleaned out.

When re-assembled get it PAT tested, at least pass a large current through the earth wire to check for a good contact. If necessary replace the input cable.

 

[Mr. Haney]

Thanks duke 37. I attacked it from the handle side and accessed the brush holder assembly. I noted that while the field windings don't appear burnt, there's a whitish substance sporadically present on and around some areas of the windings. Is that indicative of burnt shellac, carbon dust or something else?

Since the last post, I've discerned that I don't have a broken carbon brush but that both brushes came out of their shafts when I extricated the armature. I was advised to replace the brush holder assembly because the brushes shouldn't fall out, as in they should stay in place because they're retained. But that doesn't make sense to me. It would seem to me that retaining the brushes in a fixed position would cause them to lose sufficient contact with the commutator over time with wear, which is why they're continuously "pushed" by springs in order to maintain constant contact with the armature as the brushes wear down. While that makes sense to me, I'm no expert when it comes to newfangled gadgets.