[Boatanchors] DM-28 Dynamotor Restoration Questions

[hwhall at compuserve.com]

If you can't find an exact replacement, look for small motor brushes that you can file or sand down to the right dimensions.

WayneWB4OGM
-----Original Message-----
From: whitebear1122 <whitebear1122 at comcast.net>
To: boatanchors <boatanchors at mailman.qth.net>
Sent: Fri, Apr 3, 2020 3:16 pm
Subject: [Boatanchors] DM-28 Dynamotor Restoration Questions

I've got the unrestored BC-348R on the bench as I'm eyeballing it for restoration.  I pulled the dynamotor as I would like to use the radio with the original dynamotor if possible.  I disassembled the dynamotor to lubricate the bearings following the instructions here "https://radioblvd.com/bc348_dynamotor.htm" .  It came apart fine.  The bearings shown on the website are for a DM24 where the balls themselves are visible from the outside and available for cleaning.  Radioblvd didn't remove the bearings but instead cleaned them out while attached to the armature. On mine, the balls themselves are not visible.  They might be on the other side of the bearing where I do not have access since it's facing the armature.  This suggests that the press fit bearing needs to be removed from the armature.  I'm concerned here because I've never done this before..  Does anyone here have experience with this dynamotor bearing situation?  

Then, while carefully removing the brushes, I observed that one of the brush wires was broken.  I was really (really!) careful when removing the brushes.  Not yanking or using force, but gently pulling on it. Three of the four slid out nicely, but on one of them, the spring and wire came out but the brush was left inside as they were not attached.  I knocked the brush out with no problems.

On the damaged brush assembly there is a nubbin of wire coming out of the brush, around 0.030" long.  I'm going to try and tack solder a stranded wire to that nubbin, maybe using some 28 gauge buss wire wrapped around the brush wire and new stranded wire.  Chances of success are iffy.

If the brush cannot be saved, what are the options at this point?  I took at look on the Web and didn't see anything about military spare parts kits for the DM28 or any used brushes for sale.

Can a non-original used brush be put into a dynamotor where the armature is used to the contour or wearing of the 'original brush"?
If so, does anyone have a brush for the DM28 that I could purchase?  The brushes are stamped AJS.  

Thanks.  73, Scott WA9WFA  


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