Instructions on Adding a Foot-Pedal to a HF TIG Welder

Posted 1/25/14

Goal: Add foot pedal to Harbor Freight Chicago Electric TIG Welder 240 Volt Inverter Arc/TIG Welder with Digital Readout, item#98233, and be able to switch back to torch-controlled TIG welding.  We will want to be able to set the Max Amps on the panel.

Purpose:  To help my fellow Do-It-Yourselfers... to be that shining beacon I wished I had!

Consumable goods needed:
1.  TIG Welder Foot pedal- 7 pin connector is what I used as example in my instructions.  Only 5 of them are actually used, so if you found a 5-pin, that could work too.  Just be prepared to get a female 5-pin connector.  If you can't find one, you can rewire with the male connector of next item.   Avoid getting one with a 1k Sliding Pot... but if you need to replace, get a 10k Ohm Sliding Pot.  Will 4.7k work? I have no idea.
2.  A female 7 pin connector (aka bulkhead).  The one I ordered (http://www.aliexpress.com/item/7-pin-1Set-Socket-connector-cutting-TIG-Welding-Torch-JW935-6/501175830.html) came with a male connector as well.
**Note** I was having some difficulty keeping my fat wires in the pin-sockets, so I simply eliminated and bypassed it altogether, so now my foot pedal is soldered directly to the welder.  I won't be able to disconnect them, but I don't really need to either.  I wouldn't recommend using the bulkhead unless you decide to drill a hole in the face of the welder and attach the bulkhead there, preventing the wires from becoming exposed and thus more likely to become detached.

 

3.  2PDT (2-pole-double-throw) On-On Switch.  Can be found anywhere.

4.  Wires.  I used 18 ga non-tinned copper wiring.  Had to grind down the sides of the ends a bit to get it to fit in the 7-pin connectors.

5. Solder, Electrical Tape (liquid-tape is best), 3-way connectors can work too.

Tools:

1.  Soldering Iron

2.  Wire Cutters

3.  Pliers

4.  Volt/Amp/Ohm Meter-to test connections

5.  Small but strong flathead screwdriver to remove screw in knob (Amp control) to detach knob from potentiometer 

6. Small to medium zip-ties to hold wires in place afterward

7. (optional) a drill to make holes in the front panel for the switch and outlet to the foot pedal (I just ran the wires through the front slits/vents

8. (optional) masking tape and pen to identify which wires go where on the female connector and switch

Diagrams:

Diagram 1-Full Schematic

Conceptions:

Be able to switch from 1. torch-controlled circuit, 2. foot-pedal circuit.  

1. The torch-controlled circuit consists of the panel potentiometer and the HF switch in the torch

2. The foot-pedal circuit consists of the panel pot, the foot pedal pot, and the HF microswitch in the foot pedal.

Diagram 2- Same Schematic, Different Layout

The welder receives signals from two main areas--- 1) the top circuit board for amp regulation (the panel potentiometer connects to this board) and 2) a red and black coil on the bottom of the welder for HF- signal.

Steps:

-Preparation:  Remove screws and cover from welder.  Remove knob of potentiometer/amperage regulator by unscrewing screw on knob using flathead screwdriver and remove potentiometer for easier manipulation.  Cut any zip-ties.

Panel Pot! Take her out, strip her a little...

1a. Strip (but don't cut) the center two inches of insulation off the blue wire connected to the panel pot.

1b. Wrap and solder a new wire at this bare space, pull the other end through the vent and be prepared to solder it to the #3 pin of the female connector to foot pedal.

2a.  Cut center of black wire between panel pot and board

2b. Extend black wire from board through vent to center pin of switch.

2c. Extend black wire from panel pot with 2 wires (Y-shaped), 1 will be connected to switch (see diagram 1), the other will be connected to #1 of female connector of foot pedal.

3a. Strip 2 inches off the black wire between the torch's HF outlet and red/black coil. (See Picture 2)
3b. Wrap and solder a new wire at this bare space, and pull the other end through the slot and be prepared to solder it to the #7 pin of the female connector to foot pedal.

Pic 2 Red/Black Coil.  Red is cut, black is stripped

4a. Cut red wire (between coil and HF outlet).  

4b. Extend red wire from coil to the other center pin of switch.  

4c. Extend red wire from HF outlet to switch (see diagram 1).  --It may help to poke the wire from the outlet out a vent in the bottom of the welder, and extend it there.

5.  Connect a wire between #2 of the female connector and the switch (to make connection with red wires of coil and torch outlet)

6.  Connect a wire between #6 of the female connector and the switch (to make connection with black wires of board and pot)

7.  Make sure all connections are soldered and insulated with electrical tape/brush-on tape.  Use zip ties to prevent wires from accidentally shifting and touching the cover/panel or circuit board with a bare wire you may have missed, or tape came undone.

8.  Test her out!

Operation:

Switch to torch-controlled to set max amps.  Click (don't hold or you'll burn out HF circuit) to push Argon gas through welder and torch.  Switch to foot-pedal and get weldin!

Final Tip... You may need someone to help you to hold the wires in place when soldering the wires on the female connector to foot-pedal.  Even with the "helping hands" I had trouble keeping everything in place.   ** Also, start with the center (#7) pin, and then do the outside pins.

Also, you may want to read my blog to see some of the pitfalls I went through when trying to get this done.

If you have any problems, questions or comments, email me at cawineartist@gmail.com or post on my blog, and hopefully I'll get back to you!