MG 10EE starts OK, then long delays restarting

Apologies if this issue has been addressed previously. I cannot find any discussion of it.

My 1941 motor generator 10ee has had an issue with starting the spindle in either forward or reverse shortly after turning the spindle off. Throwing the switch in either direction does not do anything. If I leave the switch in the fwd/rev position, eventually the spindle will start. Often, it was not even noticeable as I would not try to turn the spindle off and then back on again without pausing to perform some operation (reposition part, change tool), but for some projects this issue can be very annoying. Lately, it has been taking a longer period of time between when the spindle was last stopped before it will be able to be started again (a few minutes where it used to be maybe 30 sec). I need to get this fixed.

The generator seems to work great. When the DC motor that powers the spindle runs, it runs normally as far as I can tell. There does not appear to be any issue with the fwd/rev switch and nothing is obviously wrong with the electronics at first glance. I figured I'd reach out and see if someone has a fix or suggestions before I get too far into it.

MikefromIowa said:

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My 1941 motor generator 10ee has had an issue with starting the spindle in either forward or reverse shortly after turning the spindle off. Throwing the switch in either direction does not do anything. If I leave the switch in the fwd/rev position, eventually the spindle will start. Often, it was not even noticeable as I would not try to turn the spindle off and then back on again without pausing to perform some operation (reposition part, change tool), but for some projects this issue can be very annoying. Lately, it has been taking a longer period of time between when the spindle was last stopped before it will be able to be started again (a few minutes where it used to be maybe 30 sec). ...

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I sounds like your Anti-Plugging (AP) relay is sticking in the open position. (The AP relay is the middle relay at the top of the panel.) If enough oily dirt accumulates on the top of the coil, the arm can stick temporarily to the top of the coil. Dampen a piece of cloth from an old T-shirt with contact cleaner and pull it between the arm and to coil:


Cal

Yes, this was exactly the solution. I feel a bit foolish now that I know after all this time it was such a simple and inexpensive fix. Much time and aggravation has been saved. Thank you Cal.

I attached a few photos in case anyone else has this problem and wants to see what the offending relay looks like. It was easy to visually verify that it was simply sticking for a period of time in the open position after the spindle was turned off.

MikefromIowa said:

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I attached a few photos in case anyone else has this problem and wants to see what the offending relay looks like.

View attachment 342061

Click to expand...

Your panel uses a Struthers-Dunn (SD) model SD42-S-14 relay for the Anti-Plugging (AP) relay. That's typical of older MG panels, especially the inline-exciter version. Later round-dial panels used a second SD CX3334 relay (like the one to the right of your AP relay) as the AP relay.

Cal