Foot Pedal Malfunction

[tom_tom]

I was practicing running beads on some thin aluminum flashing the other day and kept burning holes in it. It was odd because I set the dials as I'd done before when I had success. Used same gas flow rate, same filler, tungsten and all. Pressing the pedal beyond the arc start point would produce lots of hissing and popping. After some fussing around and troubleshooting, I discovered that the pedal was cranking out max amps when barely pressed. In other words, the first bit of travel after switching on the HF provides the same current as if the pedal were floored. The center of travel seems to be the 'zero' region where the minimum current is supplied or pure HF when low amps are set and the arc will not start due to insufficient current and work/tungsten cold. Thereafter, the current is more or less linear until I hit the end of travel or 'floored' region.

I take it something is misaligned in my pedal and hopefully can be fixed easily. It didn't exhibit this strange characteristic during the first several days I used my 250EX which leads me to believe that something slipped and the pot is misreferenced. In the meantime, I've been quickly mashing the pedal to the center of travel and slowly increasing toward 'floored' so I essentially have only the second half of the pedal travel to work with.

I want to be sure that opening the pedal won't void the warranty. If not, how do I go about cracking'er open? I have the new style pedal BTW. I'll test the resistance at various points when I find the pinout diagram (seen it here somewhere).

Tom

p.s.: It might just be my tired eyes but I don't see a "troubleshooting" or "tech support" section in the forum. Feel free to move this if there's a better place for it.

[Kempy]

If it is the new style you just push the pivot pins in and the top comes off and you can see how it works maybe the screw on the pot gear came loose just reset the pot back and tighten the screw see post 49 on http://www.everlastgenerators.com/fo...h-availability there is a picture of the inside by Glenn (Depdog). Good luck.

[Blaster]

I too have been fighting my pedal since it got colder. I had something similar happen to me and what I noticed (on my PP256) was that when the pedal was acting just like a switch (Full Power as soon as I pushed down) was that my digital display would max-out at only 247A instead of the 250A I was used to seeing (with the pot on the front of the machine).

When this happened it was because of the connection at the machine (7-pin) being loose. I eventually had to spread the pins (M) and close the sockets (F) to fix it.

Read what I went through here -> http://www.everlastgenerators.com/fo...-is-this-right

[tom_tom]

I measured the resistance of each leg--wiper directly at the pot. All seems OK. Each varies from ~2 ohms to ~47.7K ohms as the pedal is actioned. There doesn't seem to be any slippage of the teeth inside the pedal. Note that those values are with the pedal unplugged from the machine. I tried wiggling the connector - no change observed. It fits snug so I don't think any of the pins have a bad connection. Also note that the problem I outlined in my OP only happens when the main amperage is set low. The pedal pot resistance doesn't jump or skip at all as far as I can tell.

This could well be an issue within the machine, itself. Can anyone suggest a route to diagnose?

Tom

[Rambozo]

I measured the resistance of each leg--wiper directly at the pot. All seems OK. Each varies from ~2 ohms to ~47.7K ohms as the pedal is actioned. There doesn't seem to be any slippage of the teeth inside the pedal. Note that those values are with the pedal unplugged from the machine. I tried wiggling the connector - no change observed. It fits snug so I don't think any of the pins have a bad connection. Also note that the problem I outlined in my OP only happens when the main amperage is set low. The pedal pot resistance doesn't jump or skip at all as far as I can tell.

This could well be an issue within the machine, itself. Can anyone suggest a route to diagnose?

Tom

First make sure your start amps, end amps, upslope and downslope are all zeroed out for use with the pedal.

A few things spring to mind. First off, if at all possible try to use an analog meter to check the pot. Digitals, even those with a bar graph, just never seem to catch intermittent dirty pots. Or if your digital has a min/max function, you can try that, resetting it for each area you want to check and looking for any captured readings out of that range. A dirty pot will typically go to a very high impedance on one or both sides when it makes a poor contact. Also you should check at the output pins of the connector, as that will catch things in the wire. It is possible to have breaks or intermittent shorts in the cable. For tests on the whole system, get something thick and set the torch up to about a fixed 1/8" gap, then you can play with the pedal while you are watching the output on the display. From what you have described it really points to a bad pot, but more testing is required to confirm that.