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  #31  
Old Mon 30 July 2007, 21:41
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Greg,
When you use the G203 stepper drivers, on the PMDX-122, place the JP1 jumper on pins 2 and 3 to select common ground. You need to tell Mach 3 to send the step and direction pulses Active-HIGH because you are sourcing the signals. That means that the normal state of the signal, when it is off, is LOW or near ground potential. When the signal goes high, it is sourcing current and is active.

The BOB buffers the signals from the parallel port to the G20x stepper drivers. It does NOT invert the signals. The state of the signal (high or low) is passed directly to the G20x.

(The confusing part of this is that for those using the G201 or the G202, do just the opposite. Set JP1 jumper to pins 1 and 2 and set Mach 3 to be Active-LOW. The G201 and G202 sink current, so their normal off state is at 5V and their on state is at 0V.)

By the way, Greg, you're coming along a lot faster than I did when I first tried my hand at electronics.
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  #32  
Old Tue 31 July 2007, 05:16
Greg J
Just call me: Greg #13
 
Hagerman, New Mexico
United States of America
Thanks Mike,

That makes perfect sense.

As for me picking this stuff up fast ... well .... its just fun. Its bad when you go to bed thinking about all this and wake up at 0500 without the alarm wanting to read a manual.

Coffee's ready, got some reading.

Again, thanks.
Greg
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  #33  
Old Fri 16 November 2007, 19:03
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Gerald,

Since grounding has come up as a topic over the past couple of days, could we go back a few months and discuss what you wrote in post #4 of this thread?

Quote:
Originally Posted by Gerald_D View Post
Standard practice with a Gecko supply is to connect the - to the chassis, to the whole control box, and that is also connected to the ground of the incoming 110V line. Which means a lot of points need to be connected to those terminals. In your case, take good wires from those two terminals to the connectors on the DIN rail. The DIN rail connectors are easier to bridge for multiple wires.
By now, it's no secret that I'm electrically challenged so it probably won't surprise you when I say that I've read and reread what you wrote and I can't figure out how to do what you've written here. I think I understand the second half of the quote. I should run a wire from the + terminal to a terminal on the DIN rail and jumper it so that I can connect four wires to the Geckos. Same thing with the - terminal on the PS. In the first half of the quote, are you saying that I need to run a ground wire from the PS chassis to the lug on the control box enclosure in order to ground it? That would seem to make sense.
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  #34  
Old Fri 16 November 2007, 20:22
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
In this post, the - terminal of my power supply is the screw on the capacitor, the one nearest to the Gecko's. And there you can see how busy that screw gets. The point I was trying to make in the quote above is that the little terminals of the Antek are inadequate as serving as the main terminal points and that the DIN rail terminals need to be used to "jumper" the wires together. But you got that. The first part was just to say that "many" things have to get connected to the terminal, and I wasn't trying to be precise as to "how" to connect them.

The power supply chassis is screwed to the mounting plate in the control box, which in turn is screwed to the outer control box enclosure. If you use those "star" washers, or even just spring washers, which bite through the paint, you don't need to add any ground wires across those mechanical connections - they are sound ground paths. Same with alu heatsink plate, that's also soundly connected to the rest of the enclosure.

So you have all the mechanical parts forming a single big "chassis". Now you need to connect 3 wires to this big "chassis":
1. from the negative (-) terminal of the Antek power supply (either directly or via some "jumpering" in the DIN connectors)
2. from the metal parts of the table/gantry/car/slide
3. from the building's ground in the incoming mains power cable
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  #35  
Old Sat 17 November 2007, 00:46
gmessler
Just call me: Greg #15
 
Chicago IL
United States of America
I'm a little confused about the grounding issue as well. In the thread "my steppers giving trouble Mike says

Quote:
Many engineers consider it safe to connect all DC GROUND conductors together. Many engineers also consider it safe to connect all DC GROUNDs and AC Earth GROUND together. You must verify that only the DC HOT or PLUS conductor is switched. Whenever possible, I float the DC GROUND. What that means is that there is NO connection between the DC circuits and the AC circuits except through the transformer.
As I read it there shouldn't be an issue grounding the DC negative. But would it be better to Float it?
Question is either to float or not the DC ground. Will floating that ground effect the way the shield on the stepper cables is grounded?

Also to maintain opto isolation between the PMD122 and the 203v's should you not want to connect all the DC negatives together?

I'm not aware of any switching of the DC that needs to take place so I assume (bad idea) that the comment about switching the DC was a general statement.

I don't mean any disrespect Gerald or Mike. Just want to make sure I hook everyting up correctly and don't end up with any smoke.
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  #36  
Old Sat 17 November 2007, 03:40
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
No problem Greg.

In my thinking, the issue of whether or not to connect the DC negative to ground relates to potential interference of signals. It does not relate to smoke or safety. Mike is the expert with these things. I merely repeat what I've heard from a group of experienced people and what has worked for me.
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  #37  
Old Sat 17 November 2007, 04:16
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
If everything is properly grounded, using the method that Gerald has described, then having a common ground for all power supplies will work very well - and would be the best method in this case.

The main problem that I've seen in devices that have failed when a common ground point is used has been 100% due to incorrect wiring or switch failure. When a switch is used to switch only the ground side of a circuit, which should never be done, bad things can and do happen. When a two-pole switch is used that switches both the + and the - side of a DC circuit (which may be required by code for safety reasons to lock-out a circuit for maintenance), and the switch fails with the + side welded, bad things can and do happen. But I've never ever had a problem with any device that had all of the grounds connected together and only the + side of the circuit was switched.
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  #38  
Old Sat 17 November 2007, 07:56
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Crystal clear. Thanks Gerald and Mike.
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  #39  
Old Sat 17 November 2007, 09:03
gmessler
Just call me: Greg #15
 
Chicago IL
United States of America
Best to stick with what works. Thanks guys
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  #40  
Old Sat 23 August 2008, 05:52
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Any other source for ready built ?

Hi All,
Anyone has/knows another source than Antek for ready built power suppliesat reasonable prices ?
Reason Iím asking is, since august 14 I have left 3 messages to John voce box at an interval of +/- 3 days each + 2 at the general reception last week asking for anyone to call back since I want to place an order for a power supply !!.
As of to day, still no reply either by phone or email ???
Thanks, Robert
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  #41  
Old Sat 23 August 2008, 07:26
Richards
Just call me: Mike
 
South Jordan, UT
United States of America
Robert,

When I first started my test-bench project, I bought an Avel Y236801 500VA 25V+25V from Parts Express (currently $79.29 plus shipping) and a PMDX-135-8020 power supply board (currently $119 plus shipping). Those two parts are all that you need to build a power supply. If your power supply requirements are 50VDC or lower and the current requirements are 10A or less, PMDX also has the PMDX-136-5010 ($55 + shipping).

I have also built several power supplies with toroidal transformer, a computer grade capacitor (large "can" type, 15,000uF or greater), and a bridge rectifier; however, finding large computer grade "can" type capacitors is becoming more difficult. The smaller "snap-cap" type, which are designed to be soldered to a mounting p.c. board, have taken over.
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  #42  
Old Sat 23 August 2008, 12:00
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Robert,

Based on my experiences with John at Antek and Mr. Richards' reassurance, I built my own power supply. Piece of cake. Take one evening and read some of the websites and I think you'll feel comfortable enough to try it.
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  #43  
Old Sat 23 August 2008, 14:43
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Thanks Doug for you support
Iím totally in favor of your direction.
Mr Richard, you & many others out their give me the assuring push to go there, making my own. Actually, I may add, it feels more coherent with the MM approach, built your own.
Sure itís easer & to some safer to buy one, but also fun & rewarding making one ?!
Iíll look in to that, Robert

BTWÖ What do you mean by Based on my experiences with John at Antek....
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  #44  
Old Sat 23 August 2008, 21:37
Doug_Ford
Just call me: Doug #3
 
Conway (Arkansas)
United States of America
Robert,
I guess you weren't a member of this forum when I had my problems. I ordered a PS from Antek and it took forever before I received it. I had to call several times. Then I changed my mind and decided I wanted a different voltage so I ordered another one. Both times, Antek charged my credit card on the day I placed my order. I made several calls about the second one and never received it. Finally, I gave up and built my own. It still took forever to get the charge for the second PS off my credit card. I was never cheated by Antek but I found them to be extremely slow to respond. I believe John is an honest guy but he's either very disorganized or very overworked.
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  #45  
Old Sun 24 August 2008, 06:46
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Hi Doug,
Thanks for your input
Sorry if my memory or my lack of not searching, I should of look at your personal page before asking
Iíve been lurking and reading on this forum since early 2006, so Iíve read some, remember some and, hate to admit at my age (43), forgot some
In your case, my hope for John is let say heís a little victim of his success, that is overwork mixed with some disorganization??
Sorry to hear you did not get good service out of what seemed to be a fairly good business !
Regardless, Ií am still challenge & fascinated by this making my own, but if itís = or more expensive to make, I may vote to buy ?? Iíll see the out come if John has time or means to call back and show some interest in my business, as little it may be !!
Later, Robert
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