Lack of horn rotation - Leslie 145

[Dave Bryce]

So, my Leslie's horn stopped rotating. Belts look okay, feels like there's energy in the capstan, but it's not turning - almost like there's brake engaged...but if there is, I don't know where the control would be for that, or how it got engaged in the first place...and I thought that braking stopped both upper and lower - lower seems to be moving fine.

 

What else should I check/should I do before calling on someone more qualified?

 

dB

[mate stubb]

OK, need more info. Stopped rotating on slow only? Does fast speed work?

 

First thing to check is that the slow motor shaft disengages and drops off the tire when not energized. Could be binding.

[Dave Bryce]

OK, need more info. Stopped rotating on slow only? Does fast speed work?

Sort of...it will eventually spin up to speed when I kick it to Fast, but stops dead when I switch it back to Slow.

 

When I have the belt on the lower guide/groove on the capstan, it spins up to moderate speed. When I put it on the top guide/groove, it spins up to moderate speed, then a few seconds later spins up to high speed.

 

In both cases, setting the switch to Chorale/Slow makes it stop dead. In both cases, when it spins up, there is a sound like something is rubbing somewhere.

 

When I first turned the unit on this morning, the upper rotor wasn't turning at all at either speed, though.

 

First thing to check is that the slow motor shaft disengages and drops off the tire when not energized. Could be binding.

Not sure exactly what that's supposed to look like, but I'm not seeing anything like that. When I rest my finger on top of the capstan on top of the upper motor, I can feel a buzz-like energy in it when it's set to slow (but it's not moving). When I switch it to fast, I can feel a click and the energy feels like it stops.

 

dB

[OB Dave]

First thing to check is that the slow motor shaft disengages and drops off the tire when not energized. Could be binding.

Not sure exactly what that's supposed to look like, but I'm not seeing anything like that. When I rest my finger on top of the capstan on top of the upper motor, I can feel a buzz-like energy in it when it's set to slow (but it's not moving). When I switch it to fast, I can feel a click and the energy feels like it stops.

 

This is not something you're going to be able to see without removing the rear cover panel. When you do that, if you look in the little "motor box" in the middle compartment, you'll see that the motor is actually two motors bolted together. Found a pic.

 

http://www.retroaudiolab.com/pictures/equip/c-3/lesliemotoreassemble.jpg

 

The "motor" s actually a motor stack - two motors bolted to the silver horizontal plate. Upper motor is fast/tremolo , and the lower motor is slow/chorale. When running in Fast / Tremolo mode, the upper motor is engaged. It has a large rubber wheel you can see the edge of, above the silver plate. When you engage Slow / Chorale, the upper motor turns off and the lower motor kicks in, and there's a clever twist to the lower motor design. The armature can slide up and down, and when energized it should pop up, and the armature shaft makes contact with the large rubber wheel. So there's two things that happen in chorale mode - the motor slides upwards, and then it begins turning, and when the armature shaft makes contact with the rubber wheel, it effectively acts as a reduction gear, so you get a nice slow chorale turn speed.

 

As Moe stated, the problem is probably an alignment issue between the two motors. Super common for this to happen - perhaps the number one maintenance issue for Leslies. Often times you'll see one of the following: fast/tremolo mode works but in slow/chorale the horn doesn't turn at all. That's because the shaft is either not making contact with the rubber wheel, or it's barely making contact but not enough to turn it. Or the other failure mode, which I think is what you're seeing, is that the shaft is jammed up so tight against the wheel that neither motor can overcome the side forces on the bearing, so it doesn't turn in either chorale or tremolo.

 

In the photo you can see a screw and nut on either side of the slow motor shaft. These are two of the three mounting points where the slow motor attaches to the plate. The third mounting point is on the other side, and there is a threaded screw with two nuts that can be adjusted. Doing so lengthens or shortens the effective length of the third mounting point, which will allow the slow motor to be tilted to slightly different angles. That's how you adjust the motor alignment. Here's a drawing I found that shows these adjustment nuts.

 

http://bentonelectronics.com/wp-content/uploads/2011/12/motoradjust.jpg

 

You'll need to pull the motor stack to make this adjustment, and you'll want to be able to hold the motor stack in its proper vertical orientation somehow when you do so. I have a hole drilled in my workbench for this purpose. I just hang the motor stack off the edge of the workbench and drop a screwdriver through the motor mount into the hole and that holds it in place well enough to tinker with. Once you've done that you can plug either of the power cords into an ordinary electrical outlet or extension cord to test the alignment. Remember to have at most one cord plugged in at any time.

[WesG]

Pull the back cover off, and unplug the motors from the amp. Operate them independently with an extension chord, and watch what happens. Then tell us.

 

When's the last time you oiled your motors?

[Dave Bryce]

This is great info, guys. Thanks so much!

 

Wes, I'll try your suggestion for sure. I oiled the A100 when I got it back in August, but I've never tried to oil the motors...mainly because I haven't got a clue.

 

I imagine there's a link somewhere that tells me how to do it, what kind of oil, etc...

 

dB

[Markyboard]

If adjusting the slow motor shaft tension nuts is unsuccessful you may have a worn out O-ring or a worn spring that's used to engage/disengage the slow motor shaft from the O-ring (tire). I'm actually surprised it took this long for a problem to develop. The adjustment can be somewhat frustrating in that it is very "fussy" between being too tight and to loose.

 

Some basic parts you'll want to have on hand before you remove the motor stack(s):

 

O-Rings

 

Lower motor Stack Spring kit

 

Upper motor stack spring kit

 

If you get to this point then as Wes indicated a good oiling and cleaning is par for the course.

 

[mate stubb]

Another test - take the belt off the horn. Spin the horn by hand. Does it bind? When's the last time you oiled the horn?

 

A couple drops in the oil port on the horn may help.

[Delaware Dave]

I use hammond oil to oil my leslie motors. In the pics above there are four oiling points, two are right side up and two upside down. This is why you need to take the motors stack out, turn the unit upside so that the upside is now rightside up then oil those points. Also, on the base of the horn there is a little hole that says "oil here". I believe there is one for the drum as well but presently don't recall where it is. Since it sounds as though you havent oil them before this may well be your issue. I'd go the oiling route first.

[Dave Bryce]

I'll try the oil thing first. I'll be back....

 

Thanks!

 

dB

[Legatoboy]

sounds like a worn O ring or adjustment of the contact shaft or a blinky slow motor . . .

[WesG]

The drum doesn't need oiling. It uses a pair of sealed ball-bearings.

 

I use either Hammond oil, Leslie oil, TWG equivalents or 3-in-1 electric motor oil in the bottle with the blue label to oil Leslie motors.

[teashea]

Go to the facebook hammond leslie technicians site ---- that is the place for questions like this. They are very helpful.

[teashea]

https://www.facebook.com/groups/467940163416921/

[Delaware Dave]

The drum doesn't need oiling. It uses a pair of sealed ball-bearings.

This might be why I couldn't recall where the oil hole was...

[Joe Muscara]

George Benton told me to use sewing machine oil on my Leslie.

[Dave Bryce]

Okay...

 

It's not the horn - that seems to rotate fine. It looks like it's the rubber wheel that's not spinning correctly, and does appear to be the contact between it and the drive shaft that comes in contact with it. The drive shaft appears to be spinning at the right speeds at the right times. The rubber wheel/horn only turns when I have the motor set to fast...and even then it varies between moderate and fast speed on its own. I can hear a scraping sound as well.

 

So, I tried to take the motor stack out. I unplugged the cables, removed the two wingnuts at the top....and can't figure out how to turn the thing to get it out of the hole where it's hanging.

 

I must be a complete moron.

 

dB

 

 

[Markyboard]

There's just barely enough clearance to get it out. Hard to describe the mechanics involved but you'll see where it's at its minimal height as you lift and turn it on its side. At this point just slide it out. You won't hurt anything in the process.

[Markyboard]

Just to be sure you are lifting it up and taking it out through the upper compartment where the horn resides? It does not come out through the small boxed enclosure where it hangs.

[WesG]

Keep at it, Dave. You can do it! Mark's got you on the right track.

[OB Dave]

What everyone else said. As you lift the motor stack upward, you have to tilt the pulley towards you while also rotating the assembly. IIRC it really only wants to come out one way. Thing is damn near bombproof so as Markyboard notes, you're not going to hurt anything if you bump it a little here and there. Make sure the wires are hanging freely while you do this.

 

Told you it was a motor alignment issue

[Markyboard]

Should have replied with

to begin with. These guys do a great job with their videos.

 

And when you get to "repairing" or adjusting the slow motor interaction with the fast motor take a look at this.

[Outkaster]

My favorite Leslie

[Legatoboy]

I learned how to fix that on gigs when I was 17 after it happened the 1st time and fixed it at home ...Constant gigging or use will wear the tires out and adjustments will have to made to compensate until the angle gets out of range of the rubber tire from rubber wearing, then you have to get a new rubber tire. To steep an angle will also make the Rotor spin hang up! Additionally the slow motor engagement it optimal at almost 90 degrees or something like that, so the more the angle you need to adjust for the rubber tire engagement, the faster the degeneration of the rubber tire because it's engaging the rubber now at more of an angle. I gigged every weekend it seemed ( well almost) from 1969 to 1974 with my 145/M3 then my C3 in '72. Sometimes Fri and Sat gigs for weekends in a row. That's alot of wear and a lot of Leslie rubber tire usage from speed switches for both rotors. I always carried a few spare tires I got from the Hammond store close by me (thankfully, no internet sales then) and a little wrench for the adjustment angle nuts on the motors and screw driver to open the Leslie back... 400+ people at a packed HS Dance/Club and no Leslie rotation does not a party make! I blew at least 2-3 Bass speakers also. The Rubber Tire/Bass Speakers Blowing, Power Tubes and Low Rotor pulley becoming dislodged were the main points of failure when using a Leslie for me in those years.

[Dave Bryce]

Okay, it does appear to be the upper motor that's the issue.

 

The engagement of the lower motor axle to the rubber wheel is not symmetrical. As it spins, the mid shaft of the big motor the rubber wheel is not centered on it. This may be wear or something that's happened due to age...but that is the source of the problem - the motor is not properly spinning the perfectly round rubber engagement wheel. The tension of that belt may have been what caused this over time - it was kinda tight and it seems to have caused some kind of an even wear on that wheel, maybe.

 

I talked to brother Wayne Plorin at B3 guys - sent him a video of the noise the upper motor is making. He said:

 

Separate the motors and see if fast motor still makes noise? OK to GENTLY strike straight down on pulley in order to center it (palm of hand with glove, rubber mallet, etc) GENTLY!!!

 

Slow motor is NOT properly adjusted. When engaged, the tip of armature shaft should hit middle of O-Ring, but NOT overshoot it as video shows. This misalignment often causes the shaft to not fall away from o-ring when switched to fast, and consequently stuck on slow.

 

Shaft felt seen inside holes near fast motor pulley should be oiled - not saturated, just moistened.

 

Gonna try that.

 

dB

[Markyboard]

Interesting- haven't seen this problem as those fast motors are pretty robust, unlike the slow motors. Maybe someone dropped it on its shaft at some point? No matter- sounds like you're getting good direction. Too many inputs can be frustrating but if you need anything feel free to call me.

[OB Dave]

This can happen over time if the two alignment nuts work their way loose too. I've had my motors go out of alignment a few times, but have never had to rebuild a motor. I still think you probably just need to take the time to realign them and get the nuts cinched down tight.

[mate stubb]

You may need to replace the rubber tire.

[Legatoboy]

Dave, that's it Wayne got it ...

.

Yeah it can take a few different directions, not engage & just spin fast or get stuck on slow because the shaft won't (can't) retract or even get stuck on stop and burn out the motors etc.. the rubber tire can be worn or the angle of the adjustment screws gets thrown out of wack for some reason (moving the leslie in a Van etc..)

 

for the most part it's a pretty stable unit a 122/147, it's a 'common cold' type of Leslie problem...it eventually happens to most folks.

Do and address this once and you never forget how to deal with it.

[WesG]

I don't think your fast motor bearing could be worn enough to cause eccentric rotation without being noisy a small diesel motor.

 

Take the stack apart, give the fast motor shaft a wiggle, there should be less than 5 thou of radial play at each end and about 1/16 to 1/8" of axial play.

 

Then run the motor, watch the shaft, hopefully the bearing is not moving in the bearing holder. Then add the wheel, then add the tire, watching for excess radial runout. If you don't have any, service the lower motor, bolt it back on and adjust it for correct engagement. A fresh tire wouldn't hurt.

 

Wes