M-101 starts, but won't run

[Steve Bock]

Hi guys, long time lurker/noob.
I picked up an M-101 that had not been oiled in ten years or more. (My title says L, but I can't edit)
I took off the cover and oiled with mineral oil (recommended in these forums, and no I don't mean to start a thread about Hammond oil composition! 😆
A week later, I added some Naptha /lighter fluid, and then sprayed both motors with wd-30.
Finally after three weeks, the organ started and ran! Success, or so I thought...🤔

The next day. . It won't run anymore.

The start motor still pulls it up to speed, but when I flip the run switch, the tone wheel slows down slightly, and after a second, I can hear the gear on the start motor clicking. Doesn't matter how long I hold both switches up, it won't run.

I checked both switches with the V/Ohm meter and they are fine. The 250 ohm
resistor checks out as well.

The run motor seems to check out okay too, because if I turn the switch on, I can feel resistance to turning it by hand.

Motor alignment is good too. Everything spins easily by hand, and the TW takes 5 seconds to spin down from speed.

Ideas?
I'm stuck.

[tpappano]

I think what you have is a M100 series. Does the gear on the start motor freely engage and disengage the gear on the generator shaft when you operate the start switch? The start motor armature moves in and out to engage the gears and there is a spring in the motor that retracts the gear/armature when you release the start switch. If the motor shaft is sticking, the drag from it would probably keep the run motor from being able to maintain speed. With the power off, you should be able to push on the exposed tip of the start motor shaft and observe that it moves in and out freely and positively returns from the force of the spring. Use caution not to snag and break the tiny "oil thread" that leads from the outer motor bearing into the oil tray in the generator.
Enjoy your very nice 'new' instrument!

[Steve Bock]

I think what you have is a M100 series. Does the gear on the start motor freely engage and disengage the gear on the generator shaft when you operate the start switch? The start motor armature moves in and out to engage the gears and there is a spring in the motor that retracts the gear/armature when you release the start switch. If the motor shaft is sticking, the drag from it would probably keep the run motor from being able to maintain speed. With the power off, you should be able to push on the exposed tip of the start motor shaft and observe that it moves in and out freely and positively returns from the force of the spring. Use caution not to snag and break the tiny "oil thread" that leads from the outer motor bearing into the oil tray in the generator.
Enjoy your very nice 'new' instrument!

Thanks Tom. Yes the starter gear slides easily on the shaft, and does not seem to be binding.
When I flip the start switch, the gear pops to the left and engages its partner gear.
When I flip the run switch (after letting the tone wheel come to speed), the starter gear disengages partially from the axle gear, and produces a grinding noise.
I would assume it is supposed to stay engaged until the starter switch is released. Is that correct?

[tpappano]

What happens when you release the start switch after the run switch is on? Does the start motor gear fully retract, disengaging from the generator gear?

[Steve Bock]

What happens when you release the start switch after the run switch is on? Does the start motor gear fully retract, disengaging from the generator gear?

Yes. When I release the start switch, the gear retracts fully.
If I don't release the start switch, the gear immediately slides half way off the generator gear, and begins to chatter after about one second.

[tpappano]

Hmmm, I don't think the chattering gear is necessarily a problem... You mentioned the generator takes 5 seconds to spin down. I understand from the postings of other forum members that a well lubed two-motor TG will take 15 seconds or so to coast down. I have a M100 and a M3, and both do this. Perhaps if your TG is not quite free enough there is too much drag for the run motor to pull. Another possibility is that one of the two run motor windings has failed open. I think they are supposed to be about 180 ohms each, you would need to unsolder the two motor wires that are connected to the rightmost terminal of the ac power board, then you can measure each windings resistance.

[Steve Bock]

Hmmm, I don't think the chattering gear is necessarily a problem... You mentioned the generator takes 5 seconds to spin down. I understand from the postings of other forum members that a well lubed two-motor TG will take 15 seconds or so to coast down. I have a M100 and a M3, and both do this. Perhaps if your TG is not quite free enough there is too much drag for the run motor to pull. Another possibility is that one of the two run motor windings has failed open. I think they are supposed to be about 180 ohms each, you would need to unsolder the two motor wires that are connected to the rightmost terminal of the ac power board, then you can measure each windings resistance.

Excellent advice. I will oil again and test the motors. Thank you.

[tpappano]

May the Force be with you!

[enor]

If it's sluggish enough to spin down in just 5 seconds, it's way too draggy; and the start motor isn't managing to get the generator all the way up to synchronous speed. That's why it stops - it fails to sync up to the power grid. Oil will do the trick.

[jdoc]

what Enor said

[David Anderson]

If you want, you can disconnect the springs coupling the run motor to the TG and see where the drag is happening. I have run across Run motors with very gummed-up bearings, not to mention frozen scanners.

[Steve Bock]

Okay, I pulled the bolts off the bottom of the generator and propped it up so I could see the bearings, gears, and axles. Sprayed everything lightly with WD-40.
It works now!
It's still not as fluid and smooth as it should be though.
The generator still runs down in just a few seconds after I turn it off. I disconnected the run motor temporarily, and there was no difference. Is it possible that the bearings are just worn out from not having been oiled by the PO? Anything else I can do?

[enor]

Naphtha flush it, then re-oil and wait. My most recent naphtha flush turned an 8-second spin down organ into a 21 second one within 2 days.

[David Anderson]

Just a note that the makers of WD-40 state that it's not an appropriate lubricant for sintered bronze bearings because it contains waterproofing compounds for things like garden tools that will clog the tiny pores on the bronze bearings. The reason WD-40 works in the short run is because it's kerosene (a solvent for oil) in a spray can.

I've gotten plenty of TGs running smoothly again without WD-40. Any appropriate no-residue spray solvent will work.

[Alek Z]

Make sure that when you flip the switch the tubes light up, I had that happen in a very strange switch issue on an M3 (which has the same switches, I actually replaced it was a switch from an old M100). Very inconsistent, but if the tubes aren't lighting up then the run motor definitely isn't being engaged. I can't tell from the picture, but the oil conduit to the run motor may also be defective. This just means there's no string running from the oil reservoir on top of the run motor to the drive shaft, sometimes they break and get wrapped around the drive shaft and cause problems. Make sure that this isn't the case, and if this is occurring, remove the string and apply a very small amount of oil to the drive shaft at the motor. However, like state above, if your rundown time is less than 5 seconds, your tone generator is definitely not freed up enough. Apply more oil, and try to target specific locations which can be bad, and cause that grinding sound. I had an M3 that made a very bad grinding sound when I first got it, after I got the TG running at all. What I had to do was remove the springs, and prop up the TG from board it floats above with some 2 by 4s, and apply oil directly to the axels of the shafts that hold the individual tonewheels, oil often doesn't get to these locations as it doesn't really need to if the organ is running fine. Try not to use WD-40, but it's never killed my organs in moderation, just make sure you fill those cups up daily for a week I'd say to ensure you're getting enough oil. Sometimes when they haven't been run for a long time there needs to be a lot of new oil introduced into the system. Also try to run the organ by just holding the start motor to work in the oil. Good luck freeing that thing up.

[enor]

How does running the start motor "work in the oil"? The oil gets to the bearings via cotton wicks, that it has to penetrate, saturate and travel along. Running the generator doesn't speed up that process; all it does is add unnecessary wear to the not-properly-lubricated bearings.

[Alek Z]

Yeah after the oil goes through the wicks, I'm aware. I've brought stuck TG's back to life before so I know what it takes, I apologize if I did not convey the information properly.