GaryP65 Posted October 8, 2016 Share Posted October 8, 2016 So now that I got this thing on the road (sorta). I've been keeping an eye on my ammeter and while driving I do not see the needle moving (in either direction). I had the SG tested sometime ago when I thought it was faulty but an old timer in an alternater shop said it was good and the charging side is working. I took the ammeter out to test using a 9v battery and the needle moved so I'm sure that it's working although you all know I'm electrically challenged. The reason I started on this is that I noticed my battery keeps running low. Any thoughts? Link to comment Share on other sites More sharing options...
TonyAus Posted October 8, 2016 Share Posted October 8, 2016 Check the operation of the cutout. This is a pair of spring loaded contacts located in the starter switch. Its function is prevent current flowing back from the battery when the SG is not charging. In other words, when the engine is running the contacts should be closed. They may be oxidized or not closing fully. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 8, 2016 Author Share Posted October 8, 2016 Forgot to mention. Last time around I thought it was faulty and since I know nothing about this unit, I sent it to Myers and Tom said it wasn't too bad and sent it back to me (still charged me full price). Link to comment Share on other sites More sharing options...
cahartley Posted October 8, 2016 Share Posted October 8, 2016 The ammeter doesn't move even with the lights on? Link to comment Share on other sites More sharing options...
GaryP65 Posted October 8, 2016 Author Share Posted October 8, 2016 Nope Link to comment Share on other sites More sharing options...
cahartley Posted October 8, 2016 Share Posted October 8, 2016 ALL current goes through the ammeter so sumting wong........as if that wasn't already apparent........ I'm not sure where to start with this one. With everything shut off disconnect a battery cable, look for sparking when you touch the terminal to the post and also check with a voltmeter for voltage between the post and cable. Gotta start somewhere. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 8, 2016 Author Share Posted October 8, 2016 I have about 12.5v Link to comment Share on other sites More sharing options...
cahartley Posted October 8, 2016 Share Posted October 8, 2016 You should read 0 with everything shut off so the problem is between the ammeter and generator which leaves the starter box. The ONLY connections between the ammeter and starter/generator are inside the starter box. The starter portion is only a copper "horseshoe" which connects two poles which complete the battery to starter circuit and that is nearly indestructible. So that leaves the generator cutout which could be stuck closed. It happens, but I doubt it as you'd have fried wires if the points were stuck so this is a puzzler. Connect the battery and hit the horn. The ammeter should go FULL discharge. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 8, 2016 Author Share Posted October 8, 2016 Hitting the horn brings the ammeter to about 8 on the chage side not the discharge side. Link to comment Share on other sites More sharing options...
cahartley Posted October 8, 2016 Share Posted October 8, 2016 At least that part is working but the battery ground was changed somewhere along the line. The starter/generator is self polarizing so that's not an issue so you need to either reverse the battery or ammeter wires. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 8, 2016 Author Share Posted October 8, 2016 So now I'm thinking that maybe since the whole positive ground thing is new to me that maybe I got something wired wrong. Remember, I rewired the whole car. Check out the attached photo. Notice I put a + & - at the ammeter. + = Charge, - = Discharge Correct? Link to comment Share on other sites More sharing options...
cahartley Posted October 8, 2016 Share Posted October 8, 2016 (edited) I don't think that's correct if the meter is going to the charge side when there is an obvious discharge. But more importantly are the wires on the starter box correctly connected? BTW this wiring diagram shows negative ground so go figure....... Edited October 9, 2016 by cahartley (see edit history) Link to comment Share on other sites More sharing options...
TonyAus Posted October 9, 2016 Share Posted October 9, 2016 You might notice that in this wiring diagram the horn button is located on the driver's door - indicating pre-1924 series. Therefore negative ground. The change to positive ground was made in mid 1923. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 9, 2016 Author Share Posted October 9, 2016 One Craigs diagram yes. Mine is different. So I got bored and went out to the garage and traced my wires! Yep! It's official. I'm an idiot. Got the ammeter wires wrong on the starter switch. 1 Link to comment Share on other sites More sharing options...
GaryP65 Posted October 9, 2016 Author Share Posted October 9, 2016 OK gents... Now I know I got the wiring correct. When I turn on the lights. BAM. needle swings to full DISCHARGE! 1 Link to comment Share on other sites More sharing options...
cahartley Posted October 9, 2016 Share Posted October 9, 2016 Nah.......you AREN'T an idiot.......you DID figure it out!........ I hate that starter box too.......very easy to get confused........ Link to comment Share on other sites More sharing options...
MikeC5 Posted October 9, 2016 Share Posted October 9, 2016 With engine idling, the ammeter should be over on the charge side. How much will depend on how the 3rd brush is adjusted. Mine is up around 12 amps with headlights off, 6-8 with them on. As you drive, increased engine speed will lower output. I have mine adjusted so that at 35-40 mph, charge drops to just slightly positive with headlights on. I don't drive enough to have any issues with overcharging the battery. 1 Link to comment Share on other sites More sharing options...
GaryP65 Posted October 9, 2016 Author Share Posted October 9, 2016 So while I'm posting that my wires are now correct cuz my ammeter is registering, she doesn't want to start. Can't make this stuff up!! Unfortunately my brain is wrapped up around the starter box and I pull it out, take it apart and notice that one of the contact plates is spun. No biggie. I re-tighten, put in back together and reinstall. Nothing! What I should have done instead of bothering with the box was to jump it to see if the SG is out to lunch. So I connected it to the battery and.... nothing! Still having fun but.... Anyone want to buy a car? Link to comment Share on other sites More sharing options...
MikeC5 Posted October 9, 2016 Share Posted October 9, 2016 (edited) Do you mean the square copper contact has spun? Did it damage the insulating 'cardboard' underneath the contact? The copper contacts must not touch the anti-rotation plate or the base plate (which could cause a short when you push start button). There should also be an insulating washer that keeps the copper stud threads from contacting the base plate. This photo is after I finished converting from the cut-out relay to a diode but you can see how the main contacts should look). Edited October 9, 2016 by MikeC5 (see edit history) Link to comment Share on other sites More sharing options...
GaryP65 Posted October 10, 2016 Author Share Posted October 10, 2016 Cardboard ok I did notice that there is only one insulated washer (on the unspun post). Looks like I need to fashion one. What I'm now focused on is the SG.Why it won't spin when I bypass the starter box. Link to comment Share on other sites More sharing options...
MikeC5 Posted October 10, 2016 Share Posted October 10, 2016 (edited) You've disconnected the cable from the SG and are jumping it directly from a known good battery? It should turn. I hope the rotated terminal didn't short and cause damage when you tried to start it. If you are certain you had a good battery connected and got no response, you will need to open things up and see why it isn't energizing. The first thing I would look at is the condition and connections of the brushes. This can be done with the unit still mounted to engine. You have to loosen and remove the sheet metal hoop cover on the aft end to do this. Look for broken brush wires or broken springs (there are spring loaded arms that push the brushes against the armature (the part that rotates)) Edited October 10, 2016 by MikeC5 (see edit history) Link to comment Share on other sites More sharing options...
GaryP65 Posted October 11, 2016 Author Share Posted October 11, 2016 (edited) Yep. Disconnected, battery is good and nothing. I took off the hoop already and wires and springs are ok. The only thing I see is a little darkening on the commutator but not bad. Fingernail test shows mica is ok too. Edited October 11, 2016 by GaryP65 (see edit history) Link to comment Share on other sites More sharing options...
MikeC5 Posted October 11, 2016 Share Posted October 11, 2016 (edited) If you have a crank, I would try rotating the engine a few degrees in case the armature has a dead loop on the commutator (and it happened to stop with one of the brushes right there). If that has no effect I would get a volt-ohm meter (or digital multi-meter) and check the field coil windings (labeled series winding here). This diagram shows what and where to measure. The starter brushes can be identified as a little thicker than the 3rd brush. I can't remember the resistance values I got on mine but it should be only a few ohms (1 - 3 iirc). If reading is off scale it means an open circuit (broken wire) in the field winding and that's bad. If you decide to make the measurements, the brushes should either be disconnected or slip a piece of thin cardboard under the brush to insulate it from the commutator. If you're lucky you may have an old-time generator/alternator repair shop nearby that can actually rewind the field coils. Otherwise, check with Myers for a rebuilt unit (or maybe a good used one). Edited October 11, 2016 by MikeC5 clarity (see edit history) 1 Link to comment Share on other sites More sharing options...
GaryP65 Posted October 12, 2016 Author Share Posted October 12, 2016 Thanks for the info Mike but I'm electrically retarded and don't know how to do the readings. How about some direction? (Talk to me like a 5 yrs old please). I have a multimeter. FYI . I have the crank and rotated it but still nothing. The only thing I did do was to check continuity between the big posts. Link to comment Share on other sites More sharing options...
MikeC5 Posted October 13, 2016 Share Posted October 13, 2016 If you know how to check continuity you're halfway there! When you have continuity, the needle swings all the way to left (or is it right?). That is essentially zero resistance (resistance to current flow). When the meter leads aren't connected to anything the meter reads 'infinite' resistance . The multi-meter has several scales on the face and you need to identify which one is for ohms (ohm symbol looks sort of like an upside down horse shoe). Remove the SG fuse. Now take one meter lead and hold it on the post on the left where the cable would attach to go to starter switch box. Touch the other lead to one of the wires going to any one of the brush wires. If no response, try the other brush wires. One of them should give a meter response that will be close to zero but not quite zero. If you study the scale you should be able to estimate resistance but the actual value isn't that important; it just needs to be low (which tells us the wire winding doesn't have a break in it). Now hook one meter lead to the ground post over on the other side of SG (close to engine block) and the other lead to one of the other two brush wires (not the one just measured). One of these other brush wires should give a meter response and similar low resistance to the first one measured. If you can't get one or the other to read it means there is a wire break or bad connection somewhere and the starter needs both field coils to operate. You can also test the 'shunt' coil winding which is used for the charging part of the SG (which is the one with the fuse). Re-install the fuse and connect one meter lead to the fuse and the other to the brush that gave no response in the previous two tests. It should show a meter response similar to the starter coils but a bit more resistance. If the field coils check out OK then the problem probably lies in the commutator. It's kind of academic at that point since repair of field coils/armature isn't really DIY. 1 Link to comment Share on other sites More sharing options...
GaryP65 Posted October 13, 2016 Author Share Posted October 13, 2016 (edited) I was writing a whole dissertation but thought photos would explain better. Or do I need to change the scale? Edited October 13, 2016 by GaryP65 (see edit history) Link to comment Share on other sites More sharing options...
GaryP65 Posted October 16, 2016 Author Share Posted October 16, 2016 Any thoughts on the above would be much appreciated. Link to comment Share on other sites More sharing options...
MikeC5 Posted October 17, 2016 Share Posted October 17, 2016 (edited) Hi Gary, You can switch to the lowest ohm scale for these (2K) but it does appear that your starter field coils are OK. As for the charge (shunt coil), I was mistaken on checking it with the fuse in because leaving it connects to ground . Also, the shunt coil connects to the 3rd brush which is the one on the underside (the one not seen in your photos). If you want to go ahead and check it connect one lead to this brush and the other to one of the fuse terminals (I think it's the one you have the lead on in 3rd photo). If you get nothing, try other terminal. As for the starter, with field coils checking OK and brush connection and brushes OK, the only thing left is the armature/commutator. If you can find a generator shop that actually repairs generators, they have a tool called a Growler that is used to test armatures (but it must be removed from gen). While you have the brushes out, it may be worth trying to clean up the commutator with fine sandpaper (not emery paper). I've read that sometimes people over-oil the end bearing which results in oil on commutator which can cause problems too. Edited October 17, 2016 by MikeC5 (see edit history) 1 Link to comment Share on other sites More sharing options...
GaryP65 Posted October 18, 2016 Author Share Posted October 18, 2016 Checked the resistance on the 3Rd brush and it comes up with near 0 as well. Cleaned up the commutator even though it's wasn't too bad. I still get nothing when I try to start or jump it. Looks like I'm taking it to the shop. Link to comment Share on other sites More sharing options...
MikeC5 Posted October 18, 2016 Share Posted October 18, 2016 Well at least you should have good local access in NYC metro area to a shop that still knows how to repair generators. I would be interested to hear what they say the problem is. Link to comment Share on other sites More sharing options...
GaryP65 Posted October 19, 2016 Author Share Posted October 19, 2016 Hopefully dropping it off tomorrow. Not sure if they can but at least he said he'll check it out. Otherwise off to Myers. Shipping is a pain. Keep you posted Link to comment Share on other sites More sharing options...
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