retrofit Bridgeport Prototrak Plus

18 May 2016 14:55 #74816 by Todd Zuercher
First does your machine only have X and Y axis motors? If so are you planning to add a Z axis? It is hard to tell for sure from the pictures in your 1st post. I can only see the servo amp control wires for 2 axis (the small wires with red connectors.)

This looks like basic DC servo amps and may not be receiving any encoder feed back. They might be getting a tack or synthetic tack feed back from the old control, but from the looks of the pictures they aren't that sophisticated..

I found a manual here, but the wiring diagrams are pretty minimal and don't tell you much. (just what each cable is, not each wire)

From those I see that if there is a Z it's encoder wires would have plugged directly to the control (DRO) cabinet.

The 25pin connector on the box should have all the signals you need to connect to the 7i77, you might not need to mess with anything in the cabinet you've pictured, unless you are also adding a Z axis. All you would have to do is wack one end off a parallel port cable and connect the appropriate wires to the 7i77, (the Z encoder wires would be separate).

PS: Just because you have MagneteK servo motors doesn't mean you have Magnetek drives.
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18 May 2016 14:57 #74817 by Todd Zuercher
How many wires are on each of the red connectors?
The following user(s) said Thank You: new2linux
18 May 2016 17:44 - 18 May 2016 17:50 #74820 by new2linux
This is a 2 axes machine, sold as 2 1/2 axes (fixed z). The red plugs have 3 wires in each red block. When they go to the encoder 7 wires plus 3 more from the power supply go to each drive. I have the manuals that came with the controller, didn't have much in the way of wiring diagrams like what you have found.

Last Edit: 18 May 2016 17:50 by new2linux.
18 May 2016 19:13 #74822 by Todd Zuercher
Is there any labeling on the circuit boards for the amps, where the wires are connected? Specifically the 3 control wires from the red plugs?
18 May 2016 19:49 #74825 by Todd Zuercher
Is the old control still functional? You might be able to start it, and prob the 3 control wires to see what might be what. One wire is likely a servo enable, that the control either applies voltage to or pulls low to enable the amp. One is likely the analog signal, and the 3rd a ground reference (for the analog). (It is possible that it could use a PWM signal instead of an analog +/-10v). Once you figure out how to enable the amp, you could test the analog single with a small battery and see if the motor moves when a small voltage is applied.

The encoder should be easier to find documentation on how it is wired. Try to look for a manufacturer and part number for them.
18 May 2016 20:59 - 18 May 2016 21:12 #74827 by new2linux
The old controller is still working, the card does not have anything I can see, but will try to get good pic and attach later.
Last Edit: 18 May 2016 21:12 by new2linux. Reason: add pics
19 May 2016 01:59 #74831 by Todd Zuercher
Upon closer inspection of the two pictures above, of the breakout board (that may be generous to call it that even, since it is only a bunch of traces connecting some plugs.) It looks like the 3 control wires that go to the amps, may in fact only be connecting 2 of those wires to anything. There does appear to be a set of pins jumper-ed with a loop of wire at the amp end of the control cable (other red plug). It is possible that the jumpered connection at the amp is the enable, and the only connection to the control is the analog signal.

I guess we must assume that the control disables the amps simply by cutting power to them?

In fact I am almost certain of it. After reading some of the diagnostic procedures in the manual, one of them is a test of the control signal to the amps, by unplugging the red plug from the amp and plugging it into the "test port" on the breakout board above, commanding a move in one direction causes the led to glow green and revearsing direction past in the opposite direction causes it to glow red.

To add an amp enable circuit you will have to experiment a bit (my money is on that black jumper wire), or ad a relay or contractor to cut power to the amps like the old control.

As to your encoders they look to be the ordinary differential type without an index signal. I was able to find pictures of ones like yours that made it pretty clear which wire was which at the encoder, you probably will have to disassemble the plug to double check the pin-outs. (not to big a deal).
The following user(s) said Thank You: new2linux
19 May 2016 10:46 #74835 by new2linux
I have included the following to clarify one of my earlier posts.
The pic in post #74559 shows the back of the encoder, under the big red (from power supply) wire is the purple one, it is the 1st of 6 wires and the 7th is a larger black ground screwed to the base plate and the 2 power supply wires (red and black, larger in size), all under sealed cover.

I was under the impression (I do not know this to be fact) this was a closed loop system, and the digital read out (the method used to measure the display employs a wheel running against the side of the table for the x and the y runs against an accurately located surface located under the table) was used as input from the controller va. the rs232 cable.

Todd, Many many thanks for all your help!

19 May 2016 12:55 - 19 May 2016 13:05 #74838 by Todd Zuercher
As far as I can tell the wiring on the encoder is:
Black = 5v+ dc
Grey = ground
and the other 4 colored wires are the 2 differential pairs.
It shouldn't be hard to test with a meter which 2 wires go together in each pair.

How I would test it is, apply 5v and ground to power the encoder, then probe each of the other wires and write down the results for each wire, then turn the motor shaft a little, and retest, If all of the test results are different or all the same, turn the shaft again and retest. If 2 of the wires tested gave different results and 2 the same as before, you now know your pairs.

If someone knows a better way to test this please share it. (I know an oscilloscope would be a much better way, but I doubt you have one.)
Last Edit: 19 May 2016 13:05 by Todd Zuercher.
The following user(s) said Thank You: new2linux
19 May 2016 13:02 #74839 by andypugh
I am slightly nervous about black=+5V. Black for "hot" is standard in the US, but elsewhere black is often 0V (PC PSUs for example).
Having said that, in a black-grey pair I would probably guess US colour coding.
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