Foot Pedal Issue

[Injected65]

I was able to reach Ray today on the phone. He gave me several things to check out. I'll sit down tonight with the pedal and a DVOM and see what I can find out.


Thanks,
Chris

[JBnID]

Chris-- Please post test and results. I have a pedal on a PP205 that won't give full amps.

[Rodsmachineshop]

this mite help . I did notice pedal unit is sorta cheap built . big problem the cog gear on rheostat is on end of shaft so rheostat not always reads the same since has no support on end of long shaft when i turn the gear with my fingers reads same every time when using pedal it dont and also noticed the micro switch did not work all the time could hear it sticking when pushing on of tab on switch . sorta funny a ford tps switch is a 47 ohm switch just like this but sure made a lot better oh forgot this peddle is for a 250ex tig everlast some mods i did to my last pedal fixed a lot of problems with it , made a support for rheostat shaft and some guides to keep arm in alignment

[Injected65]

That is a different style pedal than the one I have. On mine it has the pot supported on both sides and the cog gear is turned via a small section of cog belt versus that rack style piece. From your drawings, it appears that both styles of pedals are wired the same though. I didn't get home from work until late so I wasn't able to get anything checked last night. Tonight I should be able to leave at a reasonable time though.

[JBnID]

I suspect yours is like mine. Simple and strong enough. Makes me wonder why my old Hobart pedal is 15 lbs.
I get 45 ohms and the pot seems to activate at the right time. Tiz still a mystery.

[Injected65]

I talked with Ray again today and after doing some checking it appears that there is a problem with the main pot. Ray is getting a new pedal sent out. Thanks again to Ray and Oleg for their help.

Chris

[Rodsmachineshop]

My pedal sorta goofy its from the switches mostly the pot. like the peddle , so just ordered some new better switches made my Honeywell . like china stuff but some switch they make suck and are cheap lol plus the micro switch from Honeywell has a roller on the arm not just a flat piece of metal against metal .

[Injected65]

My switch was working fine, but I had an open when checking for resistance across a couple of pins on the pot. On the upside of all of this, I am getting decently good at welding with the button on the torch. I might even have to use it more often when it comes time to do the cage in the racecar. It would be handy when using the pedal is next to impossible.

[JBnID]

Chris-- Could you tell me what you checked and how. You have much better luck getting hold of any customer support.

[Brian Ski]

Chris-- Could you tell me what you checked and how. You have much better luck getting hold of any customer support.

Not sure if you seen the post above... #23... It is a schematic of the pedal. Not sure how electrically inclined you are. Use a multimeter at the pins on the plug in the picture. (on resistance on a 1x scale) One on the wire from the middle of the pot to one of the other wires. If you hit the wrong "other wire" the resistance values will be the opposite. It would also be good to check both outer wires.

As you push down on the pedal slowly the meter should swing slowly. (As long as you have a good connection on the pins) it the meter jumps up and down erratically as you move the pedal, that is a sign of dust or a worn potentiometer.

For the switch just hook the meter's leads to the 2 pins. It should read full scale or nothing depending on switch position.

Sorry if it seems I was talking down, just not sure if you used a meter before.

BTW it might be easier to take the pedal apart and use jumper wires with clips to hold the meter's leads to the wires.

[JBnID]

Chris--
I appreciate it. I've done all that and get 45 ohms smoothly but only half power with the pedal all the way down. I welded most of the day with 2T because I needed about 120 amps but the pedal won't do it. Something is still wrong and I can't find it. The first machine was half power on all modes. This machine is full power on all modes but about half power with the foot pedal....which is where I need full power, of course.
The foot pedal is great on super thin SS though!

[Rodsmachineshop]

how a pot works = http://tangentsoft.net/elec/movies/tt15.html so could be 2 things pot not working rite or also not rite voltage going to pot from machine . only problem don't know proper voltage spec for voltage from machine , tech support would know

[Rodsmachineshop]

when the peddle is down dose it turn the pot all the way there is a stop under peddle you can adjust is it not letting peddle turn pot all the way

[Brian Ski]

Just tossing a couple ideas out... How did you test the pedal??? By the connector? If so did you try it with the pedal on the floor and being actuated by your foot? Just going through these pages, some of the pedals did not run correctly through the entire range. Maybe if you were working the pedal by hand it was acting differently. Like slipping when your foot is on it.

Also did you check both sides of the potentiometer? Meter lead on the center pin and check to see if both sides go through the range?

[Rodsmachineshop]

i tested mine both ways , i opened it up and took plug apart to see what colored wires went to what pins , did both way to make sure the wires them self was ok with a multimeter . my peddle that i never use lol since do most my welding with out the peddle since seams most these china peddle don't work very well lol . the peddle is made good but with cheap electronic i ordered some high grade pot and a good switch to install in my peddle . i had a old peddle with a old tig welder once it was nice was a old school peddle the pot was open and a wound wire pot never gave me any problems and the switch was a heavy duty push switch like a horn switch it never gave me problems ether never like carbon potentiometers . wire ones last for ever and always read smooth I bet the 50k usa made peddle everlast most likely uses a wire wound one since wire one always seam to come in even k numbers not like 47k

[JBnID]

I've tested the pot every way I know how....directly on the pins and on the plug, on the floor and by hand. Some times I get a smooth reading and other times nothing but that's likely the probes slipping (no alligator clamps). There is full motion of the pot with the pedal and strip of timing belt (no doubt a money saver over bronze rack and pinions of the Hobart) and the micro-switch works well. I estimated the highest amperage to be 100, but the highest reading seen by my buddy was 154A with the pedal nailed to the bottom.
This could be important; Under the hood it seems the amperage tops out at about 100, but a buddy stopped by and he calls out what is showing on the panel as I'm welding. Odd---The amperage doesn't jump to the highest reading when the pedal is floored...it takes half an inch of bead with the foot pedal all the way down for the amperage to finally get to the high point. It seems to start out at about 80A, hang around 100 for several seconds and then jump up in random steps from there. If the pedal is half raised and floored again the same random stepping action happens. It will drop the amps as expected, but step up over time. I don't understand electronics in general and delayed reactions seems to be very abnormal to me.

My first thought was the up and downslope settings were having some kind of effect but it's the same no matter their position.
The pedal reacts the same on AC and DC. All other controls and settings seems to be just fine and the pulse function is something that REALLY works!!!. The plasma cutter is MAGIC!!

[Injected65]

Just to add to the schematic above:


Pins 1 & 2 are hooked up to the switch. You obviously can test them for continuity by operating the pedal and making sure the switch is operating.

Pins 3,4 & 5 are the pot. This is where you check the resistance to see if the pot is working. Mine wasn't so unfortunately I don't know what values one should expect.

Pins 6 & 7 should be shorted together inside the connector. This is what tells the machine to switch over to pedal control. (not sure if this is on all machines or just the machines with the pedal mounted amperage pot)



JBnID - My gut feeling would be that maybe the timing belt has slipped on the cog pulley for the pot. Have you checked for the maximum and minimum resistance through the pot to see if it matches what you should be seeing. If the pot isn't getting full travel that would limit the amperage just like you are describing. IMO, the stepping of the amperage is a bit weird and not something I would expect out of a slipped pot though.


Chris

[Rodsmachineshop]

good article utube on pots http://www.youtube.com/watch?feature...&v=rUkrpqEmXb8.... Got my pedal to work sorta rite , its the pot the slope is drastic at end of limit dose almost nothing till almost fully turned but now get full power it was dirty and wasn't going full travel readjusted gear on pot shaft ordered a better pot a 50k pot to put in my foot peddle . dug for about and hour and found one of my old analog meter works better than a digital meter checking the pot also clean pot with crc contact cleaner made a big difference on how pot worked

[Rodsmachineshop]

china peddle 47k is what i see for pot ohms or 22 k. on everlast site = 50k if its the usa made peddle

[Brian Ski]

, its the pot the slope is drastic at end of limit dose almost nothing till almost fully turned but now get full power it was dirty and wasn't going full travel readjusted gear on pot shaft ordered a better pot a 50k pot to put in my foot peddle . dug for about and hour and found one of my old analog meter works better than a digital meter checking the pot also clean pot with crc contact cleaner made a big difference on how pot worked

BTW a linear taper pot is what you are looking for... An audio taper has a higher climb at the end of the dial... 2 cts...

You are doing good on replacing the pot. The carbon can degrade and the contact cleaner will help but not for long. Usually the carbon keeps breaking down. Good way to see if that is the problem though.