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Offline Graham Waterworth

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GEC Gemini DC drive question
« on: January 11, 2007, 04:25:11 PM »
Hi All,

I have got a GEC Gemini DC spindle drive unit, I want to know if anybody has a wiring diagram for one of these units.

I have tried the web without any luck.

Thanks

Graham.
Without engineers the world stops

Offline rcrabb

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Re: GEC Gemini DC drive question
« Reply #1 on: January 11, 2007, 08:10:14 PM »
Any numbers on the unit?
Ryan
Re: GEC Gemini DC drive question
« Reply #2 on: January 14, 2007, 10:37:52 AM »
Graham,

No diagram, but if you want my old one for components you are welcome. I replaced the one on my Boxford TCL 125 with an SMC-00 board from www.beel.ca. After upgrading the power resistors, it works fine on 240 volts in UK. Still have to fit the F to V converter from CNC4PC to allow program control though!

Regards,

Ian

Offline Graham Waterworth

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Re: GEC Gemini DC drive question
« Reply #3 on: January 14, 2007, 01:42:04 PM »
Hi Ian,

thanks for the offer but the one I have works fine and I have a second one as a backup, can you tell me where the 0-10V inputs are.

Graham.
Without engineers the world stops
Re: GEC Gemini DC drive question
« Reply #4 on: January 14, 2007, 02:26:41 PM »
Graham,

I did a lot of work trying to get a schematic diagram of the Boxford with the help of a photograph of the original drawing. It looks as if pin 3 is earth and pin 2 is a 0.1 to 8V analog signal from the Z80 board. I have a dxf file that I made before I decided to rip out all the old electrics and replace it with Mach compatible hardware. Can you decode dxf? If so I will Email you a copy.

Regards,

Ian

Offline Graham Waterworth

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Re: GEC Gemini DC drive question
« Reply #5 on: January 14, 2007, 04:48:08 PM »
Thanks Ian DXF is not a problem.

Graham.

Without engineers the world stops
Re: GEC Gemini DC drive question
« Reply #6 on: August 11, 2008, 07:41:08 AM »
Graham,

Is this a Gemini drive by any chance? It's from a Boxford 260VMC I picked up a couple of weeks ago. I've replaced the stepper drivers and installed a PC in the mill and all works well with Mach3. Now I need to find out how I'm going to control the spindle - ideally without having to replace anything else.

Many thanks if you can help...



By the way, based on my own experience to date, if you buy a Boxford machine, don't count on ANY kind of help from Boxford themselves, regardless if you're willing to pay for that help or not. If you're not an education site, they don't want to know - full stop.
« Last Edit: August 11, 2008, 08:16:12 AM by jwhitley »

Offline Graham Waterworth

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Re: GEC Gemini DC drive question
« Reply #7 on: August 11, 2008, 04:10:02 PM »
that is a gem, all you need is a PWM to 10V board to drive it.

Its not so much Boxford will not help, they can't due to the tie in with the L.E.A.

Graham.
Without engineers the world stops
Re: GEC Gemini DC drive question
« Reply #8 on: August 11, 2008, 04:46:20 PM »
Thanks Graham,

I've put the original Boxford electronics back together to see if I can find out what's going on. With the spindle off I get +8.4v across pins 2 & 3 (pin 2 as -ve small black wire and pin 3 as +ve thick red wire). When the spindle is running the voltage varies from -12v (ie a potential difference of -20v from not running) to around -20v - a range of about 8v - so I'm guessing the 0-10v range of control is in relation to another voltage supplied to the board? (as I'm getting +8v at idle)???

My understanding of electronics is rusty at best... I can see the a contactor is energised in two different ways depending on whether the spindle runs CW or CCW.

Do you by chance have a schematic of the Gemini? This might help me understand what's going on a little better.

Many thanks,
Chris
Re: GEC Gemini DC drive question
« Reply #9 on: August 12, 2008, 03:55:54 AM »
Have got a partial schemtatic from a TCL 125 which uses the same DC motor, Gemini drive and Yaskawa reversing contactor. Seems pin3 isn't GND, which is why I'm getting strange results (thanks Roy).