Simple switch on/off circuit help needed.

[dbtoutfit]

Hi,

I have a simple circuit I am trying to get to work.
My CNC machine uses a probe to touch a part with. When the probe touches the part it breaks continuity and this is seen by the machine. When that happens the machine marks the x/y or z location.

The circuit is fairly simple I am just concerned about wiring it wrong and frying a board.

I have attached a pdf that has all the info one should need to figure out how to wire this.

I need it layed out in idiot format. So I can clearly understand.

Thanks,
Eric

 

[JimB]

Maybe a bit more information is needed to sort this out.

Looking at the info which you provided in the PDF, I understand the operation of the touch probe.
But what is not completely clear is what electronics are fitted to your CNC machine.

In the PDF there are various bits of info, some of it relating to the controller for a Bridgeport TC3 or TC22.
Is that what you have, a TC3 or TC22?
If not, what do you have?

If you can give more info, that would be usefull.

JimB

 

[cowboybob]

My take is that the "Econo-Probe" won't work with the controller since its touch results in an "open" condition, allowing the 24VDC pull-up voltage.

The controller appears to respond to a grounding of pin 4 on P3, the opposite of what the above action produces.

 

[JimB]

Cowbobob, I agree with what you are saying, but, it may be possible to reconfigure the controller to recognise the opposite state as a "touch".

Also, the controller is shown as having a 3.3k pull-up resistor on the probe input, the LED and 1k resistor in the econo probe may be a bit low resistance for the controller input to change state correctly on a touch.

These problems are fairly easy to overcome, my scepticism, born of may years of being fed half a story, tells me to beware and check that the given schematic is really the controller for this machine.

JimB

 

[dbtoutfit]

Sorry guys for the delay, I changed my email addy on here and it took a decade it seem to finally get the confirmation email so it would allow me to post.

Anyways,
My Machine is a TC22 and the schematic is for my machine.
The probe is not "made" specifically for my machine but in theory it should provide the correct functions or be modified to do so from what I could tell.

I have tried (with the probe disconnected) shorting Pin4 to Pin5 and breaking continuity by hand during the probing cycle.
I also tried it backwards and Left it open and then shorted them during probing cycle.
Both were never recognized by the machine.

With the probe installed I check for continuity to the aux board and the probe is closing the circuit when in netural and opens the circuit when flexed like it should.
So it is functioning like I expected and there is no breaks in the wiring from the front to the back of the machine.

I have used the DMM to check the current, red probe on Pin4 and Black probe on Pin5 reads -40.8mV.
I do get 27v from Pin2 (24v) to Pin6 (GND)

(Update)
I pulled the 3.3k Resistor and its reading .985 on my DMM. I checked a 560 Ohm Resistor just to be sure and the DMM reads it correct.
In a perfect world should this 3.3k resistor not read 3.300?

(Updated Update)
Checked color code, its for sure a 1k Resistor not a 3.3k.
Does this change the game at all?

Eric

 

[cowboybob]

... I have tried (with the probe disconnected) shorting Pin4 to Pin5 and breaking continuity by hand during the probing cycle.
I also tried it backwards and Left it open and then shorted them during probing cycle.
Both were never recognized by the machine. ...

Try that same test at TB11, pins 3 & 4. Also, what is the voltage between pins 1 & 3 of TB11 and pins 4 & 3 of TB11 (no probe attached).

Mike, you may know this. Is there a difference between the Gnd(s) at JP11-5 and JP12-18, i.e., one floating (sensor side) and one not (power side)?

 

[dbtoutfit]

Try that same test at TB11, pins 3 & 4.

Thats what I did before but I just did it again... nothing

"Also, what is the voltage between pins 1 & 3 of TB11 and pins 4 & 3 of TB11 (no probe attached)"

(Red = (+)/(Black = (-) DMM Probe Colors
On TB11 Pin1 (+) to Pin2 (-) = 27.7v
On TB11 Pin1 (+) to Pin3 (-) = 27.7v
On TB11 Pin4 (+) to Pin3 (-) = 40.8mV

One thing I learned from this test... It doesn't appear that TB11 Pin1 is a GND

 

[JimB]

One thing I learned from this test... It doesn't appear that TB11 Pin1 is a GND

I dissagree. It more likely confirms that TB11 - 1 is ground.
Possibly TB11-4 is not ground, maybe due to a wiring fault. On edit, you may be right, I think that I misunderstood what you were saying.

I have used the DMM to check the current, red probe on Pin4 and Black probe on Pin5 reads -40.8mV.
I do get 27v from Pin2 (24v) to Pin6 (GND)

I hope you mean to say, check the VOLTAGE rather than CURRENT. Bad and incorrect terminology gets equipment blown up.
If it is wired as per the schematic, I would expect to see 24v.
Can I suggest that you check out the wiring between TB11 and P3. Turn the power off and use the meter on the resistance/continuity ranges.

I have tried (with the probe disconnected) shorting Pin4 to Pin5 and breaking continuity by hand during the probing cycle.
I also tried it backwards and Left it open and then shorted them during probing cycle.
Both were never recognized by the machine.

This suggests that there is either a wiring fault as per my comment above to check the wiring, or, that the controller is just not recognising the change of voltage as the probe touches.

JimB

 

[JimB]

(Update)
I pulled the 3.3k Resistor and its reading .985 on my DMM. I checked a 560 Ohm Resistor just to be sure and the DMM reads it correct.
In a perfect world should this 3.3k resistor not read 3.300?

Yes you have a 1k resistor.
Yes a perfect 3.3k resistor wou;d real 3.300 or 3300 depending on the ranging of the meter.

(Updated Update)
Checked color code, its for sure a 1k Resistor not a 3.3k.
Does this change the game at all?

No, it does not change the game.

JimB

 

[dbtoutfit]

I will check things when i get back.

I am confused about the polarity.
According to the schematic Pin1 on TB11 should be ground. If I place the Negative (black probe) on TB11 Pin1 and the Positive (red probe) on TB11 Pin2 it reads -27.7v.
Does that not indicate TB11 Pin1 as being a (+)?

Eric

 

[JimB]

According to the schematic Pin1 on TB11 should be ground. If I place the Negative (black probe) on TB11 Pin1 and the Positive (red probe) on TB11 Pin2 it reads -27.7v.
Does that not indicate TB11 Pin1 as being a (+)?

Yes it does, I mis-read and mis-understood your earlier comments.

I think that you need to check what voltages you get at JP11 and JP12 (Part of AUX BOB) and the wiring between there and TB11.

JimB

 

[dbtoutfit]

I know for sure that the pins from TB11 to P3 are correct to the schematic. I was thinking maybe someone tinkered with this wiring before I got the machine. Would it be advised to make sure that the wiring from the auxbob and logic board, someone hasnt swapped the pos with neg on the pins of the molex connectors?

The pos/neg concerns me and I am not sure until I get this issue solved if its worth looking at ne thing else...
Eric

 

[dbtoutfit]

Well I finally figured it out... with help of course
My friend Len (forum member) said the Volt reading (-40.8mV) and the polarity look very suspicious.
After toning all the lines I found some yahoo switched wire 39 and 40 at the Limit Override board in the back.
That's why I was getting the polarity issues and that's why the probe wasn't working.
Soon as I switched them back the probe worked immediately. (and so does the light!)

Thank You guys for all your time and help on this one it is much appreciated!

Eric

 

[JimB]

I found some yahoo switched wire 39 and 40 at the Limit Override board

That makes sense,
Glad that you have it fixed.

JimB