Hegner speed control

[Chris Raymond]

Hi, my old (1990) Hegner Multimax-18 speed control has stopped working (max speed all the time regardless of the knob setting).  Being an EE I probed the speed control PCB and I believe it's functioning OK.  However the tachometer pickup coil on the motor (see photo) reads open when I measure it.  If it's really a coil and not some Hall Effect sensor or something I would expect a few hundred or maybe a few thousand ohms when measuring the coil but it's definitely reading open.  So it appears to have failed, which would explain why the speed control isn't working.

Can anybody tell me:
1.  Is the pickup on the motor just a simple coil?  Or something more exotic?  This saw was built in 1990 so I suspect it's not too exotic.
2.  Can I buy a replacement coil?  If so, where?  A replacement motor is something like $750 so definitely not going that route
3.  Does anyone have fried motor they'd like to sell, so I can salvage its coil?

The coil is shown in the third photo, it's the device above the motor shaft with two wires coming out.

Thank you!

[kmmcrafts]

Welcome to Scroll Saw Village!

I don't have an answer to your question but, I thought if you had a local electric motor repair shop they may be able to get you the part you need. Also if you're on FB there is a page on there where the guy rebuilds Hegner saws including motor repairs etc.. Though I believe he is in the UK he may be able to answer questions or maybe even be able to help you get the part you need. I'm not certain of the name of the FB page but I think it's something like "A Saw Subject" or something along those lines. Maybe someone else will respond with the link to the FB page or if I run across it I will. 

I believe @JTTHECLOCKMAN works with electrical stuff maybe he knows something?

[Scrappile]

Welcome to the village.  Not sure but I think this is the person @kmmcrafts is thinking of.  Would not hurt to ask.

https://www.facebook.com/profile.php?id=61556589420174

[rjweb]

Talking about JT, haven't seen him around latley, RJ

[kmmcrafts]

19 minutes ago, rjweb said:

Talking about JT, haven't seen him around latley, RJ

He's been lurking I think as his profile showing he was on here 3 days ago.. 

[Chris Raymond]

Thank you everybody!  The saw is unusable at max speed - the blades break instantly.  It'll be good to have it running right again.

[JTTHECLOCKMAN]

Hello Chris. I am sorry but I will be of no help to you. I had a hegner years ago but never dove into the workings of the motor and or controller because I never had a problem. i do not know how the speed is regulated with that saw. What I suggest you do is contact Advance Machiery and talk to their tech. They will be able to answer your question and possible sell you the part if that be the case that it is bad. Being you can obviously speak the lingo it should be easy for you to hold that conversation.  I will tell you this with all certainty that motor is indistructable and you do not need to buy a new motor. That is an industrial motor. Maybe at some time the capacitor may go but again I doubt it. I believe this is a coil but does it collect data or does it produce data. That I do not know. I do know this is tied into that circuit board and you may have a different problem on the circuit board. replacing that coil may not be the answer. The speed is magnetically controlled. As I said the techs at Hegner are really good and very helpful. Great customer service. They can help. 

https://www.advmachinery.com/collections/hegner-scroll-saw-parts

Edited July 5 by JTTHECLOCKMAN

[Chris Raymond]

Thanks everybody for your help with this.  AMI contacted Hegner on my behalf (great folks at AMI), and as I suspected this is not a part I can buy (the coil is riveted, not screwed, to the motor end cap so it's not intended to be replaced by the user).  I also contacted the Facebook user "Hegner, A Saw Subject" and got an automatic reply that technical support is no longer provided.  So it looks like my options, best to worst, are 1) find a dead motor and scavenge its pickup coil, 2) find someone parting out a similar saw and buy the motor, 3) try to wind a coil myself and mount it to the motor, 4) find a cheap BLDC motor with speed control and adapt it to the saw, 5) buy a new motor from Hegner for ~ $750, or 6) replace the saw with a different one.  I'll post if I succeed in getting the saw going again.

[JTTHECLOCKMAN]

1 hour ago, Chris Raymond said:

Thanks everybody for your help with this.  AMI contacted Hegner on my behalf (great folks at AMI), and as I suspected this is not a part I can buy (the coil is riveted, not screwed, to the motor end cap so it's not intended to be replaced by the user).  I also contacted the Facebook user "Hegner, A Saw Subject" and got an automatic reply that technical support is no longer provided.  So it looks like my options, best to worst, are 1) find a dead motor and scavenge its pickup coil, 2) find someone parting out a similar saw and buy the motor, 3) try to wind a coil myself and mount it to the motor, 4) find a cheap BLDC motor with speed control and adapt it to the saw, 5) buy a new motor from Hegner for ~ $750, or 6) replace the saw with a different one.  I'll post if I succeed in getting the saw going again.

I will throw one other option out there for you. being the motor is locked in to full open speed. It may be of value for you to purchase an inexpensive speed controller to match the amps and voltage of the saw. It can not hurt. I always preach you never want to use an external  speed controller such as a sewing machine pedal on a tool that has speed control capabilities that work well. In this case they are not working at all. That is an option to explore. I am sure you already know this because like I said you talk the talk and seem to be adapt to this stuff, you would need a VFD controller because that is an AC motor. This is not a DC motor(brushes).

Edited Saturday at 01:47 AM by JTTHECLOCKMAN

[OCtoolguy]

I wish I was more knowledgeable regarding electrical theory. I'd love to follow along on this one. It seems that the part in need should be available from some supplier if you know the specs on the part used by the mfgr. Hegner can't possibly be the only user of that part. There must be other motors that use a similar system. Please keep us all apprised of your outcome.