Rock10 Posted October 18, 2021 Share Posted October 18, 2021 Our 1936 Series 40 has been converted to 12 volts. We recently found it wasn't charging. The Generator is from a 57 Chevy. I took it apart and found some missing old insulation on the field coils, but nothing that appeared to be shorted. When I checked the armature, all of the commutator segments show continuity. There is no resistance between them. According to videos on YT, there should be. Am I missing something? If the commutator is shorted, how would that happen to all of the segments? I see no damage on the part. The brushes were worn, but not totally gone and there isn't a groove where they run. Any thoughts? Thanks. Link to comment Share on other sites More sharing options...
Jack Worstell Posted October 18, 2021 Share Posted October 18, 2021 Did you also change out the VR ? The original generator was probably a three-brush and the 57 Chevy is a two-brush generator I would guess the two generators take substantially VRs Plus going from a 6V generator to a 12V generator calls for a VR change Commutator segments show continuity ??? As measured to what reference ?? If the armature is out on the bench...I don't think adjacent segments should show continuity ??? Jack Worstell Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 (edited) The VR was changed before we got it. Everything seemed to be fine until we noticed not charging a few weeks ago. The armature is out on the bench and each segment on the commutator shows continuity with every other segment. You are supposed to test them adjacent and 180 degrees apart. The videos show resistance between segments I have none. What would cause that? Edited October 18, 2021 by Rock10 (see edit history) Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 Link to comment Share on other sites More sharing options...
Oldtech Posted October 18, 2021 Share Posted October 18, 2021 You would have very little resistance between segments and I don't think that is a valid test. Check from ground to the segments, there should be no reading. If it is grounded it wont work. To test for short circuits in the armature you need a growler. If it passes the growler and is not grounded, it is good. 1 Link to comment Share on other sites More sharing options...
Bloo Posted October 18, 2021 Share Posted October 18, 2021 (edited) Without trying taking a generator apart to try it, i think its normal. You should have continuity through the field, and open circuit from the field coil to the case (with it all apart). On the armature make sure its open circuit from all the segments to the shaft. Then run it. Spin the engine up to a fast idle, fast enough that it would have been charging when it worked, and ground the FIELD terminal. It should charge like crazy. If it does, look elsewhere for the trouble. If it doesn't, take the cover off the regulator, and do the same test again while pushing the cutout relay down manually. If it still won't charge then it is generator trouble for sure. More in-depth tests of the armature or field require a growler. It probably is an armature problem if the field passes and it still wont work, but I might have some more ideas for kludgey tests if it fails to work with the field grounded. Edited October 18, 2021 by Bloo (see edit history) 1 Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 None of the segments are shorted to the shaft, just each other. Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 Where can I find a growler? Tested on the car it would not put out any voltage with the field grounded. Link to comment Share on other sites More sharing options...
Bloo Posted October 18, 2021 Share Posted October 18, 2021 And you have continuity through the field coil? Link to comment Share on other sites More sharing options...
Oldtech Posted October 18, 2021 Share Posted October 18, 2021 Any electric motor shop will have one. So do a lot of hobbyists. The charge should be minimal to have one checked. In the electrical magic of a generator if any of the windings are shorted to another from being hot, physical damage, or whatever, it will not charge. it only takes one. You may have something else going on but getting the armature checked is always a good idea, 2 Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 19 minutes ago, Bloo said: And you have continuity through the field coil? Yes Link to comment Share on other sites More sharing options...
Bloo Posted October 18, 2021 Share Posted October 18, 2021 By process of elimination it almost has to be the armature. It's still a goofy failure. I suggest getting the armature tested if you can. 1 Link to comment Share on other sites More sharing options...
Rock10 Posted October 18, 2021 Author Share Posted October 18, 2021 I'll check for a shop tomorrow. Thanks 1 Link to comment Share on other sites More sharing options...
Frank DuVal Posted October 18, 2021 Share Posted October 18, 2021 16 hours ago, Rock10 said: The brushes were worn, but not totally gone Just how worn? How long are they? Do you have a new brush to see how worn the old ones are?🤔 Link to comment Share on other sites More sharing options...
Jack Worstell Posted October 18, 2021 Share Posted October 18, 2021 Commutator sure doesn't look good. Needs a good cleaning and maybe turned down ( very lightly ) to eliminate any roughnesss And clean the groves ( carefully ) between the segments Do I think this will solve the charging problem ? Probably not....but it's not hard to do and if it were mine....I'd give it a shot Jack Worstell 1 Link to comment Share on other sites More sharing options...
Rock10 Posted October 19, 2021 Author Share Posted October 19, 2021 9 hours ago, Frank DuVal said: Just how worn? How long are they? Do you have a new brush to see how worn the old ones are?🤔 Still good material left. I've seen worse. Link to comment Share on other sites More sharing options...
Rock10 Posted October 19, 2021 Author Share Posted October 19, 2021 5 hours ago, Jack Worstell said: Commutator sure doesn't look good. Needs a good cleaning and maybe turned down ( very lightly ) to eliminate any roughnesss And clean the groves ( carefully ) between the segments Do I think this will solve the charging problem ? Probably not....but it's not hard to do and if it were mine....I'd give it a shot Jack Worstell I did a little cleaning between the segments and it looks like copper, not an insulator. 🤷♂️ Link to comment Share on other sites More sharing options...
EmTee Posted October 19, 2021 Share Posted October 19, 2021 There are mica insulators between commutator segments. If you have the commutator turned-down by an auto electric shop they will also cut the mica insulators to ensure they are below the copper surface the brushes ride on, allowing for wear. 1 Link to comment Share on other sites More sharing options...
Jack Worstell Posted October 19, 2021 Share Posted October 19, 2021 If copper particles ( from wear of the copper commutator segments ) have filled in the groves between the commutator segments ....then it seems to me that is the problem I don't recall ever hearing of this condition getting to the point of "no charge" Of course behind might be another problem of the armature windings shorted to one another. I guess this is what a "growler" test is supposed to detect As EMTee have pointed out.....an auto electric shop ....if you can find one....might be able to correct the commentator issue I see from your photos that the ID tag is still on the generator housing If you have 1950s Delco Remy reference books....you can find the correct armature replacement. But maybe it's easier to just get another generator Jack Worstell 1 Link to comment Share on other sites More sharing options...
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