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1970 Modular Drive 10EE Electrical Problem - overspeeding

RichHansen

Plastic
Joined
Feb 5, 2018
I recently acquired a 10EE that was built in 1970. The variable DC drive tube circuit is installed in the machine. I have waded through several electrical issues and seem to be getting close, but I still am experiencing issues.

The FL relay has been replaced with an Automation Direct 120 VAC ice cube relay. The spec for that relay says it needs 80% of its rated coil voltage to operate. The circuit diagram for the lathe says that the voltage across FL in series with the motor shunt field varies from 120 VAC to 57 VAC. I see no way that the FL coil will stay energized throughout the range of operation. (The ice cube was clearly an attempt to "fix" an issue. The REC 3 diodes were also blown out and replaced with 1N5348 diodes. I replaced those with 1N1084's). Not sure what do with FL but for now it’s letting me engage the main contactor.

When I put the spindle in forward, the spindle accelerates to 4000 rpm. (The speed adjustment dial has no effect on the spindle speed.) The motor runs a bit, then the overload trips. Feels like I have no field voltage but not sure what to do about it. I turned P2 counter clockwise and there was no change.

Thanks in advance for the help.

Rich
 
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Does the RPM go truly to 4000 or is it in a runaway condition due to having no field at all? On my 1967 machine, I sometimes get the runaway condition if I start the machine with the speed setting above about 2500 RPM. On the other hand, if I start the machine below, say, 2000 RPM, then I can turn the speed up to beyond 2500 and it remains controlled. I've learned to always start at lower RPM and ramp up, but it's not comfortable or efficient. I need to dig into it, but I need to make parts, too.
 
I am sure Cal or one of the other gurus will be along to help...

But the old joke about you need a EE (electrical enigineer) to maintain the 10EE rings true.
 
Does the RPM go truly to 4000 or is it in a runaway condition due to having no field at all? On my 1967 machine, I sometimes get the runaway condition if I start the machine with the speed setting above about 2500 RPM. On the other hand, if I start the machine below, say, 2000 RPM, then I can turn the speed up to beyond 2500 and it remains controlled. I've learned to always start at lower RPM and ramp up, but it's not comfortable or efficient. I need to dig into it, but I need to make parts, too.
I start the machine with the spindle pot counter clockwise (low speed setting I think). Ramps to 4000.
 
I am sure Cal or one of the other gurus will be along to help...

But the old joke about you need a EE (electrical enigineer) to maintain the 10EE rings true.
I’ve heard that you need to be a great mechanic as well as an EE. I wonder if that’s where the name came from. Problem is, I’m pretty old but too young for tubes. I started doing digital controls in the mid 70’s and the analog tube circuit is a bit baffling. I understand what the armature and field voltages are supposed to do, just can’t see how to make them do it !
 
Thanks for the comments. Tomorrow I’m planning to concentrate on the voltage across 18 to F2 and see if I can do something to make it change. I have a spare C3J tube. Not sure if it’s good but I might give it a try.
 
New info on my 1970 10EE

Problem I'm troubleshooting: Turning on the spindle it accelerates smoothly up to almost 4000 rpm. Speed adjust has little effect.

DC Voltage across 22 ~ 42 (ET1 to P1 Wiper)
P1 full clockwise, P2 full counter clockwise
Speed Control from CCL to CL
32 VDC 40 VDC (chart says 53 to 240 VDC)
Move P1 half way counter clockwise
23 VDC 38 VDC
After the spindle runs at nearly 4000, all speed settings, Overload trips ~30 seconds running
Move P1 full counter clockwise

25 VDC 26 VDC

Motor Armature Voltage S1 ~ 51 (chart says 36 ~ 235 VDC)
219 VDC with Power Contactor pulled in, spindle off
165 Low Speed 175 High Speed


I spoke with Monarch this morning and I'm checking voltage 22 ~ 27 to see if the control voltage is changing.

In testing, I put the meter across 18 ~ F2 and the power contactor started chattering. Sounds like I've got a contact somewhere that is letting some ripple through it. Signing off for now.

Any thoughts about all of this mess would be appreciated.
 
...

The FL relay has been replaced with an Automation Direct 120 VAC ice cube relay. The spec for that relay says it needs 80% of its rated coil voltage to operate. The circuit diagram for the lathe says that the voltage across FL in series with the motor shunt field varies from 120 VAC to 57 VAC. ...
OK, I'm not all that familiar with Modular drives or tube electronics, but I have a question. You say: "The FL relay has been replaced with an Automation Direct 120 VAC ice cube relay." What's the part number of the relay and is it actually an AC relay? (The shunt field is a DC circuit.) The stock FL relay's coil is in series with the shunt field, so there's a couple of Amps passing through the coil. That's not something the average ice cube relay can handle, unless it has such a high DC resistance that very little current will flow through the shunt field, which could well explain why the motor is running away.

The shunt field Voltage spec, across terminals 18 to F1, is 120 to 57 VDC, not VAC. What DC voltage are you reading between F1 and F2 (across the shunt field itself)? If it's not at least 57 VDC, then the relay is the problem. (I don't see terminal F2 on the contactor panel terminal strip, you may have to go to the terminal box on the side of the spindle motor, where you can also find F1.)
 
OK, I'm not all that familiar with Modular drives or tube electronics, but I have a question. You say: "The FL relay has been replaced with an Automation Direct 120 VAC ice cube relay." What's the part number of the relay and is it actually an AC relay? (The shunt field is a DC circuit.) The stock FL relay's coil is in series with the shunt field, so there's a couple of Amps passing through the coil. That's not something the average ice cube relay can handle, unless it has such a high DC resistance that very little current will flow through the shunt field, which could well explain why the motor is running away.

The shunt field Voltage spec, across terminals 18 to F1, is 120 to 57 VDC, not VAC. What DC voltage are you reading between F1 and F2 (across the shunt field itself)? If it's not at least 57 VDC, then the relay is the problem. (I don't see terminal F2 on the contactor panel terminal strip, you may have to go to the terminal box on the side of the spindle motor, where you can also find F1.)
Cal, you are on to something here. Clearly a typical ice cube relay would not be hogging a few DC amps through the coil. Maybe in parallel with a shunt?
 
As I said, check the field voltage, F1 to F2. It that's low, then the relay is the problem. If you then bypass the ice cube relay's coil (connect F1 to 18) the field should have power and the drive should run normally.

Motor/generator 10EEs don't have a field loss relay. They rely on the fact that losing exciter voltage (the DC field's power source) causes the motor control relays to also lose power and open, shutting down the drive. You can temporarily run the drive without field loss protection, just to verify that's the problem.
 
Cal, you are on to something here. Clearly a typical ice cube relay would not be hogging a few DC amps through the coil. Maybe in parallel with a shunt?
Cal - that was exactly what conclusion I came up with. Bottom line, it would sort of work until the field voltage started going down. Then it dropped out. Maybe someone was keeping the speed below 1300 ?!?! Anyway, I got a used/refurbished relay fro Tim at Monarch. Pricey but it works.
 
I hope I’m putting my continuing story in the right place.

Got the speed circuit almost working. Would not go below 1000. Field circuit compromised. I decided rather than continued troubleshooting on the speed control module I threw in the towel and bought the Scissio Controls tube replacements and the speed control box. Tim has done an excellent packaging / engineering job on this and the plug and play system fired right up and works beautifully. One new caveat, since my machine came from the factory wired at 460, the OL heater is sized wrong. OL trips at extended running 3000 + speeds for a bit. Replacement heater coming.

Anyone collecting tubes and speed modules, I have two sets of everything.
 
I hope I’m putting my continuing story in the right place.

Got the speed circuit almost working. Would not go below 1000. Field circuit compromised. I decided rather than continued troubleshooting on the speed control module I threw in the towel and bought the Scissio Controls tube replacements and the speed control box. Tim has done an excellent packaging / engineering job on this and the plug and play system fired right up and works beautifully. One new caveat, since my machine came from the factory wired at 460, the OL heater is sized wrong. OL trips at extended running 3000 + speeds for a bit. Replacement heater coming.

Anyone collecting tubes and speed modules, I have two sets of everything.
I did the same on my 1970 Modular. Money well spent.
 
But the C16Js don't have anything to do with the field, so replacement won't fix field problems.

Really, without measurements of the field and armature voltages for the whole speed range (at maybe 3-4 points) it's impossible to diagnose anything specific.
 








 
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