Foot Pedal

[alan levin]

I just picked up a pedal (free) from a friend. It reads, Foot Control Model #FC-V1 Code#1177 Stock#1388-0133. Two lines coming out. One line has two wires and the other has three. Can I use this on my Miller 350HF Dialarc? Thanks Alan

[awright]

Depends. Is there any identification of manufacturer on the pedal? If so, start by asking them how the pedal is configured inside and what the resistance and power rating of the pot is.

If they don't exist or refuse to give you the information, you might see if it is easy to open up non-destructively to trace out the wiring. Even without opening up the pedal yu can probably trace out the wiring using an ohmmeter.

You probably have two leads from the switch and three leads from the potentiometer. This is fairly easy to trace out. See if the two-lead cable shorts out or opens as you depress the pedal. If it does the opposite of what your welder requires, you may find that the microswitch inside is a single-pole, double throw switch and that you can simply change to the appropriate pair of terminals on the switch.

Measure resistance between each pair of leads in the three-lead cable. Then measure the resistance again with the pedal half depressed and then fully depressed. This will tell you the total resistance of the pot, which lead is the wiper, and which lead is at the minimum end and which lead is at the maximum pedal depression end of the pot. While you are at it, measure the resistance continuoulsy between the wiper and either end of the pot as you very gradually depress the pedal. Watch for erratic readings that indicate a dirty or damaged potentiometer. Pot condition is much easier to observe with an analog (pointer-type) ohmmeter that with a digital voltmeter. If the pot is erratic or incorrect value, it is probably easy to change it to the correct pot. If you do end up changing it out, be sure to get a "linear taper" pot and be sure the pot has adequate power dissipation rating. Many pots are "audio taper" for volume control applications and this is not appropriate for a welder pedal.

With this information on hand, you can call the service department at Miller and ask them if your pedal can be adapted to the Dialarc and what the connector pinout is. Miller service is reputed to be very helpful. You can also probably buy the proper connector from Miller. If they can't help you, come back here.

awright

[gnm109]

Depends. Is there any identification of manufacturer on the pedal? If so, start by asking them how the pedal is configured inside and what the resistance and power rating of the pot is.

If they don't exist or refuse to give you the information, you might see if it is easy to open up non-destructively to trace out the wiring. Even without opening up the pedal yu can probably trace out the wiring using an ohmmeter.

You probably have two leads from the switch and three leads from the potentiometer. This is fairly easy to trace out. See if the two-lead cable shorts out or opens as you depress the pedal. If it does the opposite of what your welder requires, you may find that the microswitch inside is a single-pole, double throw switch and that you can simply change to the appropriate pair of terminals on the switch.

Measure resistance between each pair of leads in the three-lead cable. Then measure the resistance again with the pedal half depressed and then fully depressed. This will tell you the total resistance of the pot, which lead is the wiper, and which lead is at the minimum end and which lead is at the maximum pedal depression end of the pot. While you are at it, measure the resistance continuoulsy between the wiper and either end of the pot as you very gradually depress the pedal. Watch for erratic readings that indicate a dirty or damaged potentiometer. Pot condition is much easier to observe with an analog (pointer-type) ohmmeter that with a digital voltmeter. If the pot is erratic or incorrect value, it is probably easy to change it to the correct pot. If you do end up changing it out, be sure to get a "linear taper" pot and be sure the pot has adequate power dissipation rating. Many pots are "audio taper" for volume control applications and this is not appropriate for a welder pedal.

With this information on hand, you can call the service department at Miller and ask them if your pedal can be adapted to the Dialarc and what the connector pinout is. Miller service is reputed to be very helpful. You can also probably buy the proper connector from Miller. If they can't help you, come back here.

awright

I second everything that awright says above. One thing that would help is to get ahold of the Miller schematic so that you can determine what resistance should be on the three wire line. On my old Lincoln Idealarc, for example, the resistance on the foot pedal is 10K ohm. Lincoln uses a 2 watt linear potentiometer that is wired with two capacitors. Each capacitor has one leg to the middle (wiper) lead on the pot and the other leg to each other post on the pot. These are coupled into the circuit to protect against voltage spikes. The ones in the Lincoln are .0047 microfarad at 3KV.

Generally the machine is designed so that it sees the 10K ohms when you start and this decreases as the pedal is depressed further so as to increase current. It only uses one side of the pot - the portion that decreases as the Pedal is moved.

The other two wire cable, as awright says, is the part that closes the switch to start the gas, water and so forth. In the case of the Lincoln, this is a normally open switch which closes when the pedal is depressed.


The funny thing about the L:incoln is that the schematic shows a 5K pot but the foot pedal measures at 10K. Go figure. Ha.

Good luck!

[alan levin]

Thanks guys for getting back. Sorry I have not been on for awhile. I do have a manual for the pedal. I will check all the info I got and get back to you.Al

[weldersales]

The number you gave is an Airco number, I believe. Did you say Dialarc 350HF? I am familiar with the Miller Dialarc HF which is a Dialarc 250 with all the tig bells and whistles included. If that is what you have, you need a 15 ohm foot control which is a Miller RFC23A - it was supplied also to Airco. A picture would help identify it or PM us and we will send picture of RFC23A. weldersales