1960 WIAD Component identification question

[Spookydad]

Can anyone identify the component in the very back of the WIAD control panel? It appears to be some sort of relay.

 

[rke[pler]

Should be the field failure relay.

 

[Spookydad]

So that is something that doesn't operate in normal operations.

 

[rke[pler]

So that is something that doesn't operate in normal operations.

Sure it does, it's a critical component in the drive. If it doesn't see enough field voltage it'll drop out and the drive will not operate. You should hear it pull in when you activate the drive after it's warmed up and you press the start button - it should engage to close the contacts to allow the armature drive to operate.

If it were not in the circuit and the field failed while the drive was operating there'd be nothing to keep the motor from revving until the windings birdnested. That's more excitement than anyone really needs.

 

[Spookydad]

OK, so that may be the root of our problem. That relay is not closing at all.

What are the risks of briefly closing it manually to see if that causes the spindle to turn properly?

 

[The real Leigh]

What are the risks of briefly closing it manually to see if that causes the spindle to turn properly?

I would STRONGLY suggest that you determine the actual functional condition of the field supply before doing so.

If there really is no field voltage, as the symptoms suggest, you could damage the machine by defeating that safety.

- Leigh

 

[rke[pler]

It's possible that the relay is failing because the field voltage is too low. Starting the drive with the field being only the residual magnetism of the motor would cause a pretty interesting (meaning possibly expensive) result. I'd start by measuring the field voltage between F1 and F2, you should have a DC voltage about 120V with the speed control all the way down while the start button is pressed. If you're not seeing that then there are other possibilites, such as ELSR in neutral, 6NO60 failed, start button contacts bad, overload open or the main contactor has failed.

 

[hitandmiss]

The root of the problem is that the motor does not have enough field to safely run.
The relay is preventing operation because it is not safe to do so.

"What are the risks of briefly closing it manually to see if that causes the spindle to turn properly?"

The risk is very high, and the spindle WILL NOT turn properly!

These motors will start and run with no power to the field.
They can easily run over 4000 RPM with only 24 Volts on the armature.
This is 1/10th the normal operating voltage for the armature. Higher RPM's are possible with more armature voltage, up to destruction of the motor!
This is way over speed for the motor, and can damage the motor, the control, or hurt someone.
There are VERY large, white hot sparks shooting 6" to a foot from the commutator of these motors running with no field, that could start a fire.
This is not normal operation, and things can get very very ugly in a few seconds.

It is best to get the field circuit working properly, so the relay closes verifying that the the field has power, BEFORE trying to run the spindle.

Having repaired machinery for over 40 years now, I have seen way too much carnage that was caused by "trying to make it run" without correcting the reason that is preventing it from running properly.

I hope this points you in the right direction,

Bill

On Edit. rke[pler was posting while I was composing.

Additional failure points: The field winding could have opened up, it should be around 100 Ohms between F1 and F2.
Wires breaking from flexing. And several other possibilities in the control.

 

[The real Leigh]

It's possible that the relay is failing because the field voltage is too low.

That is absolutely NOT a failure.

It's operating as designed, implementing a safety-critical override.

- Leigh

 

[hitandmiss]

Perhaps supplying the missing words would help.


... relay is failing to operate because the field current is too low, or missing.

 

[peterh5322]

The WiaD uses an EL1C to supply 115 volts dc to operate the DC Panel and certain other functions, while the pair of 3C23s supply the field and the pair of C16Js supply the armature. The FF relay provides an interlock to ensure that the field regulator is operating before the armature regulator may operate.

Contrast that with the M-G in which the exciter supplies 115 volts to operate the DC Panel and the raw voltage for the spindle motor field rheostat section and the raw voltage for the main generator field rheostat section which, in turn, supplies the spindle motor armature. It the exciter fails, then there is no power for the DC Panel, no power for the spindle motor's field and no power for the main generator, and the machine comes to a safe stop.

 

[Spookydad]

Ok, I got the message, don't touch the relay! (This is why I asked first)

I got 3v across F1/F2

We replaced the two tubes that are glowing blue in the pic below with spares and began the tuning procedure yesterday. (I am not at the monarch's location so I can't check the numbers) The new tubes glow much brighter than the old ones but now the main contactor doesn't close when the start button is pressed. The minimum voltage has been turned to the maximum we can get (+35v)

http://www.practicalmachinist.com/v...2t-10ee-wiad-spindle-not-turning-dsc09637.jpg

 

[The real Leigh]

I got 3v across F1/F2

Is that AC volts or DC volts?

With this kind of failure you need to read both voltages.
Your AC measurement must be made with a meter that blocks DC voltage and reads only AC if both are present.

If you have any significant AC voltage (more than about 1 volt), it's very likely that the filter capacitors are bad.
These are the weakest components in any power supply. Their failure rate is many times higher than for any other type of component.

The bright rectifier glow is consistent with a filter capacitor failure, specifically being caused by high leakage current through the cap(s).
This can happen as a precursor to complete failure (short).

Technical stuff
=========
An AC to DC power supply consists of a transformer, a rectifier, and a filter network.

The rectifier is the tube. The components between it and the control circuit are the filter network.

Capacitors are part of the filter network. Their duty is to change pulsing AC to nice smooth DC.
If they fail open you end up with pulsing AC at the load. If they fail shorted you have high fault current and hopefully blow a fuse.

- Leigh

 

[rke[pler]

The EL1C rectifier in front of the 3C23s should have a nice glow. It might be there but all I can see is a thumbnail of the image.

 

[Spookydad]

Is that AC volts or DC volts?

With this kind of failure you need to read both voltages.
Your AC measurement must be made with a meter that blocks DC voltage and reads only AC if both are present.

If you have any significant AC voltage (more than about 1 volt), it's very likely that the filter capacitors are bad.
These are the weakest components in any power supply. Their failure rate is many times higher than for any other type of component.

The bright rectifier glow is consistent with a filter capacitor failure, specifically being caused by high leakage current through the cap(s).
This can happen as a precursor to complete failure (short).

Technical stuff
=========
An AC to DC power supply consists of a transformer, a rectifier, and a filter network.

The rectifier is the tube. The components between it and the control circuit are the filter network.

Capacitors are part of the filter network. Their duty is to change pulsing AC to nice smooth DC.
If they fail open you end up with pulsing AC at the load. If they fail shorted you have high fault current and hopefully blow a fuse.

- Leigh

There is a fairly steady 45v AC across F1 (Neg probe) and F2 (Positive probe) and a -0.5v I thought the DC might be a measurement issue but it is very repeatable.

SO which ones are the filter capacitors?

 

[The real Leigh]

There is a fairly steady 45v AC across F1 (Neg probe) and F2 (Positive probe) and a -0.5v I thought the DC might be a measurement issue but it is very repeatable.
SO which ones are the filter capacitors?

OK. Definitely sounds like open filter caps (which is much better than shorted filter caps).

I'm afraid I don't know which ones are the relevant filter caps in the WIAD, since I have no documentation on that drive.
I'm sure others here can answer that question.

- Leigh

 

[Spookydad]

Would a 2200v capacitor from a microwave oven work as a replacement if the capacitance values match?

 

[The real Leigh]

Would a 2200v capacitor from a microwave oven work as a replacement if the capacitance values match?

Technically yes, assuming it was small enough to fit in the original position.

HOWEVER, I would never do that.

Microwave oven capacitors anticipate a very short duty cycle, only a few minutes per day. Consequently I would be very suspicious of their quality.

I've never heard of one failing, but I've never cooked anything for eight hours.

It's very much like motor start capacitors, which are the cheapest trash that can be called a capacitor.

- Leigh

 

[9100]

I have been following this thread and staying out of it, but it is time to offer some advice. You obviously have no idea of what you are doing. Get the manual for that particular lathe from Monarch and then find someone who knows how to work on this type of circuitry.

Bill