PMDX 407 Need help

[aa1pi]

I have the PMDX 407 and at this point I have tried several different combinations of wiring with no sucsess.
I am converting an early model SpectraLight, it presently has a potentiometer.   The speed control is made by Minarik Electric  model  MM31002A
I first tried taking the three wires from the pot and wired different combinations to J3 , I tried a separate power source. I also tried two wires on J2 and 1 wire on J3 out.
although using J2 started and stopped the spindle motor ,I still had no speed control.
                                                                                            Regards  aa1pi

[Bob at PMDX]

You don't mention the model number of your speed controller so I can't give you a specific answer.  If your speed controller is similar to that on Sherline models, take a look at this doc:
    http://www.soigeneris.com/Document/Gecko/Using_the%20Gecko_G540_VFD_Output.pdf
specifically the picture on page 4 that shows the pot and run switch connections.

Presuming your controller has a switch for "run/stop" (called an "inhibit" switch in the above doc), then you will need to connect the 2 wires from that switch to J2 on the PMDX-407.  It does not matter which wire goes to which terminal on J2.

The 3 wires from the pot should go directly onto J3.  The only issue is figuring out which wire is connected to the speed controller's positive supply reference and which is connected to the negative supply reference (these are usually the 2 outer wires on the 3-terminal pot).  If you have a volt meter, measure the voltage between the 2 outside wires from the pot.  Switch the meter probes around until you get a positive voltage reading.  The wire on the negative meter probe (usually the black probe) will go to the "Agnd" terminal on J3, and the wire on the positive meter probe (usually the red probe) will go to the "Aref" terminal on J3.  The middle wire on the pot should go the "Aout" terminal on J3.

In the above mentioned doc, this would be:
    P1 to the PMDX-407 J3 "Agnd" terminal
    P2 to the PMDX-407 J3 "Aout" terminal
    P3 to the PMDX-407 J3 "Aref" terminal

If your speed controller is nothing like the one in this document, then let us know the model number and I can give you a better answer.

Bob

[Steve Stallings]

Oops.... the Inhibit input on these controllers will stop the motor when the
output on J2 of the PMDX-407 turns on. On the other hand the document
that Bob referenced was for the motor controller supplied by Sherline. It
may be that SpectraLight supplied a different motor control.

Please tell us the specific model of motor control that you have.

The INHIBIT input on DC motor controls such as Minarik and KBIC (Penta)
units is NOT fail safe (motor will start if a wire comes loose), nor is it compatible
with the output on J2 of the PMDX-407 because its operation is inverted from
a Run command.

We normally recommend that you switch the mains power coming into this
type of controller using a contactor relay such as this:

http://www.pmdx.com/ContactorMD20-120

The coil of this contactor can be controlled by passing 120 VAC through J2
on the PMDX-407.

[aa1pi]

Thanks for the quick replys. After removing the controller I found the model number. The speed control is made by Minarik Electric , Glendale CA. model  MM31002A   115 volts.
 

[aa1pi]

I found the manual for the controller I have     https://www.minarikdrives.com/descriptions/document/250-0101.pdf

[Steve Stallings]

OK, the MM31002A is one of the most common style controllers. The speed
control connections should be:

PMDX-407            MM31002A

Aref                     S3
Aout                    S2
Agnd                   S1

The Min speed pot should be turned all the way down.

The Max speed pot should probably be turned all the way up, unless
you know that when using the original external speed pot, this would
cause the motor to overspeed.

It appears that the voltage supplied by the MM31002A at its S3 terminal
is only +5 volts with respect to S1. You should be able to confirm this
with a multimeter, but be careful as this point is NOT isolated from the
line voltage. You should also be able to vary the voltage between
Aout and Agnd from 0 to almost 5 volts using S word settings in
Mach4.

The issue with the INHIBIT input on the controller being opposite of
a RUN signal and the warning about failsafe operation still apply. If
you need further help with wiring a contactor relay to control the
mains input to the MM31002, let me know.

[aa1pi]

Steve ,I tried this combination And it didn't work for me, before asking for help,I can see that this is the obvious connections   S3 to S1 = 54 VDC  and S2 just touching the volt meter to this connection sends the motor into high speed.
   Page15 of the manual shows the common at a different location  INH2  I WAS IN HOPE THAT LED TO THE ANSWER OF THIS PROBLEM.
cOULD YOU PLEASE LOOK AT THIS AGAIN,   A LINK TO THE MANUAL IS IN A SEPARATE POST.
  BEST REGARDS
                        AA1PI

[Steve Stallings]

I hope that the S3 to S1 voltage is 5.4 VDC not 54 VDC.

Can you connect just S3 and S1 and take some measurements
between Agnd and Aout of the PMDX-407 without any connection
to S2. You should be able to vary the voltage on Aout from near
zero to close to 5 volts by varying the S word setting. This is
equivalent to having an external speed pot and turning it to get
different voltages.

Touching S2 without it having a drive signal may produce results
that are meaningless because it is high impedance and can pick
noise and respond to that.

As for INH2, my best guess is that it is almost the same as S1
except that the Min speed pot is bypassed. It should not hurt
anything to connect Agnd of the PMDX-407 to INH2.

[aa1pi]

Hi Steve,
                      The voltage was not 54 VDC
     
      s3 to s1     is 4.96 VDC    not connected to anything.
     
      S3 connected to AREF
      S1 connected to AGND     voltage between S1 & S3     is  1.592 VDC

      AGND to AOUT    is  1.379 VDC

      The voltages are with the samrtbob and 407 off

      With the smartbob and 407 off I connected the S2 to AOUT the spindle motor started.
      next I turned the spindle on in MACH4 the PMDX 407 LED's come on with the PWM being medium brightness.
      next I tried to calibrate and had no response in increase or decrease in speed

       you referred to " S word "   where do I find this ?  I am using MACH4

           Regards   Bob aa1pi      aa1pi is my amateur radio call sign.   I have test equip including O scope

[Steve Stallings]

OK, lets tackle things incrementally.

The 1.592 volts is showing that the PMDX-407 is loading down
the reference voltage coming out of terminal S3 on your motor
driver. When you get a voltage from S3 (Aref) and S1 (Agnd)
that is significantly lower than 5 volts then we are faced with a
motor driver that has a very low current capability on its reference
voltage output.

Given that they show a 10K ohm pot in their manual, this
may indeed be the case. The way around that is to use
an independent power supply for the 5 volt reference.

To use an independent power source for the reference, you
must have an isolated power source. It cannot be shared
with any other part of the circuitry in your machine. Choose
a 5 VDC regulated supply.

The negative side of this supply should connect to both
the Agnd on the PMDX-407 and to the INH2 terminal on
the motor driver.

The positive side of this supply should connect to the
Aref on the PMDX-407. It does not connect to the motor
driver at all.

The Aout on the PMDX-407 should connect to the S2
terminal on the motor driver.

Once we get this working, then we can tackle the Run/Stop
control issues.

[aa1pi]

It's alive !
        Thanks Steve that combination worked. The motor starts and stops on command from MACH4   I also adjusted  the calibration pot to calibrate
per instructions, after running for about two minutes the motor would dip in speed and then resume to high speed. It evening here and I will look into it tomorrow, my first thinking is the adjustments on the motor controller. I would like your ideas on adding a relay for the spindle power. Does J2 act like dry contacts, could I switch a motor contactor 115 v  using J2 ?
 
     Regards   Bob   aa1pi

[Steve Stallings]

The terminals of J2 on the PMDX-407 are from a miniature solid state
MOSFET relay that can switch up to 80 milliAmperes at up to 150 volts
AC or DC. Yes, they are like dry contacts.

We offer a small single phase contactor that works well for this application.
See:

http://www.pmdx.com/ContactorMD20-120