[sunppeli]

Does anyone know how to wire a 7-pin foot pedal to work on a 3-pin welder?
Pics:




From the 3-pin switch goes red and black wires to the connector. From max current potentiometer goes the blue wire to the connector and the green to the pedal pot. From pedal pot green and yellow wires to the connector.

Thanks for any possible help!!

[Otto Nobedder]

I know my way around the 7-pin connection, but I've never dealt with a 3-pin remote connector.

What machine is it? Someone here may be familiar with the machine, and between us all, maybe we can sort it out...

Steve S

[sunppeli]

This should be the correct pedal for my welder:
http://image.pushauction.com/ViewPictur ... e554fc7480
So actually it should have 2 connectors which makes a lot more sense. I think a 7-pin is used when there is a switch in the machine to choose between pedal and torch switch. On this machine both switches cannot be plugged in at the same time.

I looked at the connector of my pedal and it only uses 5 of the 7 pins! So I guess the wires from the switch should go to the torch switch and the 3 wires from the pots to the pedal connection. So the only problem now is to find out which way do the wires go..

[Otto Nobedder]

Ah, I see...

The question at hand, then, is which pins at your machine are for the "ends" of the pot, and which is the "slider". I'd use a high-impedence volt-ohm meter, and probe each pin against circuit-board ground (machine on). Look for +5VDC... might be 12, but I'd expect 5. That's the + side for the pot. Then look for zero ohms on (probably) the 2 Kohm scale, that's the ground side for the pot. The odd man out is for the slider.

Two cents... and good luck.

Steve S

[Colt45GTO]

just a thought and not really much help to the OP, kind of a thread hijack...

this setup i have arcmaster 175TE doesn't support a peddle but does support a remote... whats the difference? correct me if i am wrong....

a torch mounted switch/button activates/deactivates the current, a peddle does much the same thing but (minds gone blank) alters the ampage/gas flow the more or less the peddle is pressed/released. whats different?

[Otto Nobedder]

A simple on/off remote only requires two wires. TamJeff is set up this way (his machine is full-remote capable, but he prefers a simple manual on/off thumb-button for that anodized Al he does such wonders with). A full remote, like a pedal or thumbwheel, controls on/off and amps, from machine minimum to panel setting. It has no effect on the gas flow rate.

Both systems, on the right-featured machine, can allow for timed pre- and post-flow of gas. Jeff does not have pre-flow, or doesn't use it, as he needs his current the moment he hits the button, but I'm sure he has at least 20 seconds of postflow for that aluminum. That way, gas coverage is not interrupted between pulses, and after the last one he keeps gas coverage until the metal is cool enough not to go "ugly" when the gas stops.

Hope I understood the question, and that this helped answer it...

Steve S

[Colt45GTO]

yes Steve, i understand and thanks for clearing that up

[sunppeli]

Big thanks for your help! I opened the welder and tested the pins with a meter. The results are weird.. None of the 3pins are ground and there are no voltages either. I tried to just guess the wires and soldered them to the connector(i found the correct females from an electrics store). Seemed to work good before trying to weld, the amps shoved from12-110 with the pedal pot on max when rocking the pedal. When i tried to weld, it just sputtered and melt the electrode.. With the 3-pin connector off, everything works just fine.

Any more ideas? :/

[sunppeli]

This is how the welder looks like:

Tomorrow I'll look at it again.

[Otto Nobedder]

Okay, so the pedal pot seems to control the amps, according to the indicator?

Try probing pin to pin? The two pins with the greatest voltage between them may be the "ends" of the pot. See if that jives with the way you've wired it.

If they're mixed up, then you have a "current divider", rather than a voltage divider.

Once you're confident the configuration is right, and if it still doesn't work, throw that last switch on the right to "4t" and try again, just for the hell of it. Also, throw the arc-force, peak current, and basic current all the way right, just experimentally.

This configuration seems very like Lincoln's Precision TIG 375, and I'm trying to remember all those variables for a pulse-capable machine, but it's been a few years.

Steve S

[sunppeli]

Thank you!!

[Otto Nobedder]

May I assume you have solved the problem?

(There were two "exclamation points...")

Steve S

[sunppeli]

Sorry, not yet, I didn't have time to look at it yet.. Maybe this weekend I'll follow your instructions!

[sunppeli]

Working now! I just tried different wirings and I finally got it. I can open the connector again and check which way do the wires go if anyone is interested.

But there is still a problem.. With the pedal pot set at max, it only gives around 100amps. I'm thinking the resistances of the pots may not be suitable for this welder? This is not a big issue because I usually weld thin aluminium and more than 100 amps is rarely needed.

[sunppeli]

I'll have to get back to this again.. Turns out 100 amps is not enough for my needs. I'm thinking the resistance of the pedal is too high for my welder? So I need to lower the resistance by soldering an extra resistor parallel to either (or both?) of the pots, or changing the whole pots to ones with less resistance. I'm very bad with electrics.. I wonder if the problem is about the resistances at all? Could the ends of the pots still be connected the wrong way?

Some more help would be extremely appreciated!!

[sunppeli]

Does anyone have on opinion on this? I'm thinking halving the resistance on the max amp pot might solve the problem?

[WerkSpace]

A potentiometer is a voltage divider. I think you want to increase the resistance of the pot.
The wiper will be used to pick off a voltage that is typically used to bias the control circuit.

Normally, you would have maximum voltage at one end of the pot and zero at the other end,
but if the potentiometer has additional resistors in its series circuit, then the pot will be tuned
to adjust voltages within the design of the circuit, as each resistor drops a predetermined
amount of voltage based on the current that flows through the circuit.

I had a similar problem with my welding helmet. I bought some Swiss adjustable shade optics
in the bargain bin at my local welding supplier for $20 (but the control pot was missing.)
I installed a 90 Megohm pot to make the circuit work correctly.
Once the optics were working, I glued them into my existing helmet with silicone adhesive.

As soon as my 50K linear pots arrive from eBay, I will be making a finger tip torch control
for my Everlast PowerPro205. I've got a few designs in my head but they need testing.
I don't plan on investing much money into this project, its just for fun.
http://www.ebay.com/itm/4pcs-50K-ohm-Po ... OC:CA:3160

Does anyone have on opinion on this? I'm thinking halving the resistance on the max amp pot might solve the problem?

[sunppeli]

Thanks for your reply! I was thinking that the resistance would resist the voltage going back to the welder to adjust the current up. So it actaully works the other way? I guess I'll try adding a simple resistor in series with the pot and just and see what it does.

[WerkSpace]

When you add a resistor (in series with the pot), you offset the range.
You most likely will not get the desired effect that you are looking for.
It will however, help determine the value of the potentiometer required.
Be sure to try adding the series resistor to either side of the pot at one time,
in order to determine which direction the amperage range is being offset.
i.e. If you are getting 0-100amps, you may get 50-150amps as an offset.
In order to get the full amp range, you must change the value of the pot.

Thanks for your reply! I was thinking that the resistance would resist the voltage going back to the welder to adjust the current up. So it actaully works the other way? I guess I'll try adding a simple resistor in series with the pot and just and see what it does.