Starmill Spindle Controller Info \ Advice Required

All info relating to the Denford Starmill CNC milling machines

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paragon
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Starmill Spindle Controller Info \ Advice Required

Post by paragon » Tue 30 Jan , 2007 14:17 pm

Dear Group,

I have owned a 1988 (aprox) Denford Starmill for a couple of years.
I have been using RTLinux EMC as a control method by wiring the L297 / L298 stepper drives to a PC parallel port via Optical Isolators.

While doing some debugging of the spindle controller board I mistakenly shorted out one of the three connectors that controls the motor speed.

Since then I m only seeing aprox 3vdc on two of these pins but should be seeing 12vdc (aprox).

The controller uses 2 * op-amps and 2 * SCR's to deliver be 0 - 180vdc to the spindle motor.

Unfortunately I don’t have any details of the board at hand but the company seems to have disbanded.

Does anyone know how this spindle speed controller works?
Does anyone know the Starmills spindle motor amp rating? (I can’t see the info on the label as it has peeled!
Additionally could anyone recommend a cheap replacement?

I have tried to debug / reverse engineer this board but am having trouble as my experience with op-amps and SCR's is limited.

My first thought is to change the op-amps as I presume these would be the first things to fail. I have replacement SCR's also. Any thoughts on this?

Kind Regards,
SRG

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Steve
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Post by Steve » Tue 30 Jan , 2007 15:09 pm

can you upload a picture of the board?

paragon
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Post by paragon » Tue 30 Jan , 2007 15:33 pm

Hello Steve,

Thanks for your reply.

I can't upload an image right now as I am currently at work and the board is at home.

But I can take a photo and post it later this evening.

Cheers
Steve

paragon
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Post by paragon » Wed 31 Jan , 2007 11:38 am

Update :-

Replaced op-amps, SCR's, 12v Regulator and Transistors.

I now have 12V at onside of the pot (speed input 3 connectors) but the dc output is 240VDC constant.

I decided to buy a new board off of an ebayer in Canada for 35ukp including shipping which I think is good value as to buy here in the UK is at least 100ukp.
It has the same connections as the Starmill Controller with the addition of stop / start.

If anyone is interested here is the ebay link of the motor controller I have opted for :-

https://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... &rd=1&rd=1


Manual / Spec
https://www.beel.ca/smcmanual.pdf

Regards
SRG

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