Amps don't reach preset while welding, is this right???

[Blaster]

So I've been doing a lot of 1/4" 6061 Alum lately with my PP256. Sometimes it seems like, at a joint I've been doing repetitively, I'm just not getting the heat I need. The same heat I had before (it seems like that maybe, but I'm not sure). I slow down, work both sides, do a better job of preheating before I start but, I get by....

Today a buddy of mine stopped by and I said to him [i]"Tell me what happens to the Amp Display as I weld". I was surprised to hear him say 154, 177, 191, and the like with the pedal floored. The Amp knob is all the way up, the display says 256 (sometimes 255/254), and during the post purge 24.

I'm using the pedal, a CK 250A WC torch, and the ground clamp is directly on the assembled piece, and the machine connections to both the Ground/Torch are tight.

As I said, I only notice it now and then, I'm not sure what the display was reading at those other times. I think it doesn't happen when I first start welding for the day (at least I know I've finished for the day and thought "Didn't feel like it had the balls it should have on those last few welds, I hope nothings wrong,,," and then the next time I start welding I'm reassured because it does just fine).

Shouldn't the display be reading 250A if the pedals all the way down as I weld????

[performance]

Running with the pulse, it will move around, and definitely not show max amps. Depending on the balance and the frequency settings, the readings will change because of the way the meter is calibrated. Also if the foot pedal gear has slipped on the belt, it could read less.

[everlastsupport]

Yea, make sure the pulse is off. That will cause the display toggle between the amp levels.

Also you can ohm the pedal and make sure it is going all the way. 3-4 and 4-5 are the pins to check ( low to 50K and 50K to low on the two). Do you get all the power you need with the trigger?

So glad I am not typing from my samsung tablet

[Blaster]

Come On guys,,,, If I was in Pulse, I would have mentioned it

120Hz - 30% - 1/8" electrode all the regular settings for doing new 1/4" Alum...

BUT, my pedal IS giving me some surprising readings from 3-4-5

I get 3-4 2Low and 35-40High (Off to Full)
I get 4-5 55High and 20Low "

In 3-4 I Go Full and get different readings each time, usually 35-38 Ohms but never higher than 40. Does this mean I have a problem with my pedal? I'm gonna open it up and take those reading from the Pot itself to eliminate a problem with the wire (which I have repaired from having dropped a 300Ltr cylinder on it from 8" off the cart, but maybe another conductor got damaged I didn't notice )

But, to be clear, you're saying the digital display should read 250A while welding, Full Pedal, no-pulsing, if it's set to that?

[Paul Moir]

Yeah, or near to it.

Sounds like either the sprocket on the pot is loose, or the pot is going south. It should be at least consistant. (ps "20Low" is in Kohms not ohms right? It's not autoranging right? And "55high" is in K ohms too right? You know, only a factor of 1000x here! )

[Blaster]

OK, so I opened the pedal and was surprised to find things looking so Out-of-Wack

First, the Belt isn't fully running on the cogged Gear, it's 1/2 derailed because it isn't lined-up with the relief in the roller that the belt stays centered in. I can only assume it was assembled this way and not that way it's designed to be.

Second, the Belt and Gear appear to have differing TPI (or per mm I'm sure) because the teeth engage fully in only 3-4 places then ride-up, on top of each other, on the way to the attachment point (not the spring). Whole thing looks kinda Mickey Mouse to me.....

Just getting it open is an experience in poor design. Really,,,,, #1 Phillips (or ISO I guess) pointing down to the floor. These tiny screws are the "feet" I slide the pedal around on? THEY won't be going back! I picked the crud out of them but still had to resort to pliers to get 'em out...

So here's what I had at the pot (I knew I could repair a wire properly ) Grey=5 / Brown=3 / Green/Yellow=4 / I assume 3 is the wiper.

With the pedal "Floored";

.............55
........... /...\
........../.......\
....Grey...Brn..Gr/Ye
......\......../\......./
.......\...../...\...../
.........35.......22


After realigning the gear and resetting it's position;

.............55
........... /...\
........../.......\
....Grey...Brn..Gr/Ye
......\......../\......./
.......\...../...\...../
.........54.......55

The only thing is, the "at rest" readings for 3-5 I can get to 1 BUT the 3-4 is about 5 (if I adjust it lower it doesn't hold, drifts into the 100's so I assume it off the mark inside) Also I made sure the Phillips Screw "Stop" was hitting...

Is this going to be OK, as long as I have 5-3 at 55 pedal OFF and 3-4 at 55 FLOORED?

What's with the Belt Tooth / Gear Tooth mismatch? Is this going to continue to give me trouble?


.

[everlastsupport]

Sounds like the rack and pinion (belt and gear) in the pedal skipped like Mark said. We had to mention pulse to cover other things people do miss. Did you test full power without the pedal?

[Blaster]

Didn't try, just opened the pedal. I haven't yet welded with it. I assume this will make a difference!

[joshuab]

Something doesn't add up in your measurements. A potentiometer of value R should always measure R between pins 1-3, and the values of pins 1-2 and 2-3 should always sum to R. With the pot fully turned one way, you should read 0 ohms between 1-2 and R between 2-3, and with the pot fully turned the other way, you should read R between 1-2 and 0 between 2-3.

In your second diagram, you show 55 ohms between 1-3, which is consistent with the pot value that was given previously, but then you show 54 ohms between 1-2 and 55 ohms between 2-3, which would only be correct if it was a 109 ohm pot, in which case you should measure that value between pins 1-3.

[everlastsupport]

he is checking at the foot pedal plug not the pot inside.

[Blaster]

I actually AM at the pot,,, and joshuab is Absolutely correct! I may not have remeasured 1-3 (4 to 5 in this case) the second time, I was trying to get the numbers equalized and give the greatest range. This DID NOT WORK - hehehe It "made a difference" alright, when I went to weld I had 6-16A full range.

I tried to readjust it a couple of times, had some interesting results. Everything from a constant 254 to an almost workable 35 - 250. I thought "I want that 6 back, I might need it someday". So, I forgot the meter and made 1/10th turn adjustments hoping to find the "sweet spot" that gave me both Low/High. THEN things got UGLY....

I got inconsistent results I couldn't account for. Turns Out, the Gear-to-Shaft connection won't hold. I LOVE the Welder, but,,,, WHAT A PIECE OF CRAP this Pedal is!!!! What a crappy design, everything from the bottom "screw feet" to the belt (which it turns out is the crux of the problem because at the new low temps, it doesn't flex right so it jumps teeth) to the cheesy way the Gear is retained to the shaft. Believe it or not, little coarse threaded sheetmetal screws are jammed into plastic holes and their pointy ends are expected to hold the oversized hole in the gear to the potentiometer. And, of course, you're only gonna get a couple tightens on those plastic holes

"Rack & Pinion" it is NOT! It's probably why other pedals actually have Racks...

So, I'm taking it all apart to improve the gear retention and I'll start again. I guess what it is I'll be looking for is 27.5 for both 1-2 & 2-3 (wires 3-4 & 3-5) if 1-3=55 right?. And one assenting and the other descending with travel, each ending at the 55. I hope this works, I'm not sure but is it possible there are no "stops" to this pot? It just goes 360 around & around? I'll find out for sure when I take it apart I guess...

[JimMinKent]

Search for "Power Pro tig pedal issues" There were a few tweaks and fixes to these pedals covered there.

http://www.everlastgenerators.com/fo...g-Pedal-Issues

[Paul Moir]

I'm pretty sure I've got my sprocket pinned to the pot shaft now. I just drilled through the whole thing once I got it near where I wanted it. Those "set screws" were kinda funny when I saw 'em.

The screws on the bottom of the pedal are worn to the point where they pretty much don't have heads anymore. I cut in slots last time I had to have it apart.

Mine's given me good service now that the pot's been replaced (it was an attempt at a good pot, three wipers, but only one ever contacted..), the spring has been better secured to the "rack" (mine tore out), and the sprocket got pinned (mine spun too). But it's no fun to use and frankly I should have got an SSC years ago.

[Blaster]

Jim - Thx for the link, interesting reading, I should have look for myself I guess....

I took it apart, files the corners off the Gears Teeth (round file the right size) and the belt already rounded teeth. Hope that resolves the jumping.

But Now, I'm lost as to the actual NUMBERS I need to reset it to. I find, at rest, that 28.71K is "center". That is, both 3-4 & 3-5 are equalized at this but, it "Bottoms Out" the pot too quickly (Long before the stop can be adjusted to stop more movement at 54.4K). So, I try setting it so BOTH start at @3K and goto 54K (one Up and one Down but the ends are around the same for each). All I get is a constant 240A...

How should I adjust the pot?

[Paul Moir]

If the pot is doing "funny stuff" when it bottoms out, it's done and needs to be replaced. It should go down to just about zero (55k on the other side) and stay there. If you travel it any further it should hit the pot's mechanical stop and stay at just about zero. By "just about zero" I mean say ~0-2K ohms

[joshuab]

If the pot is doing "funny stuff" when it bottoms out, it's done and needs to be replaced. It should go down to just about zero (55k on the other side) and stay there. If you travel it any further it should hit the pot's mechanical stop and stay at just about zero. By "just about zero" I mean say ~0-2K ohms

What he said. With the pedal up, you should measure very low ohms between pins 1-2 and 55 ohms between pins 2-3--or vice versa. It depends on how the pot is wired up. With the pedal down, you should measure the opposite. As you press the pedal down, 1-2 will scale from 0-55 and 2-3 will scale from 55-0 (or vice versa), proportional to the amount of travel. The values on 1-2 and 2-3 should always sum to 55. And 1-3 should always be 55, no matter what position the pot is in. If the pot deviates from these conditions, then it is messed up and needs to be replaced--but do be careful you are taking correct measurements, because pots are pretty robust as long as you don't wear them out from twisting them 500,000 times OR twisting them too hard and physically breaking them. It's really unlikely that a pedal pot would experience that kind of abuse. Even if the rack was mis-adjusted, it wouldn't have enough force (I would think) to break the pot.

[JimMinKent]

You are getting some good help from the guys here, I think you will be up and running right very soon.

I think you can leave the actual values alone for now, since from what you describe, the pot seems to work without any dropouts or crunching/scraping noises. I think it's really a matter of mechanical operation at this point. Unless yours has the wrong parts, or broken parts, it should be able to be adjusted to work as designed. I took mine down to a bare case and buffed, lubed and adjusted everything before I ever used it, and it has been without problems for two years.

The amount of travel of the pedal, it's length of pull on the belt, and the rotation of the pot are set by the designers and should work without needing any changes to that geometry. Make sure the belt and gear fit as good as possible. On mine the belt did not seat very far into the gear teeth until I groomed them. It would easily skip a tooth on a quick let-off of the pedal before I worked it over.

Adjust the pot to it's rotational stop with the pedal at its upper "Off" position, this will give you the lowest low amperage. Lock the gear down to the shaft. Next the micro switch needs to be adjusted to switch On with the first few thousandths of pedal travel, so it will actually turn the machine On while the pot is still in those low ohm ranges.

Watch for proper action of the gear and belt through full range. Hook it up, and test it in DC with a DC clamp-meter. That way you can also test the calibration of your display at various points.

That's about all you can do with the stock parts, but stick with it, they should work well.

[joshuab]

BTW, when I say "pins 1-2" and "2-3" I mean the pins of the pot, NOT the pins of the connector. The pot-pins map to pins 3-4-5 of the connector, if memory serves.

[Blaster]

OK, I'm Finally DONE!!! And Here's Why it took So LONG....

Initially, this was a belt problem I think was exacerbated by the Cold Weather. Thank you All for your help in repairing that. Next I could NOT get proper operation no matter how I adjusted the Pot (which, really, I was adjusting properly from the start. I guess in my After diagram above I should have been more clear by labeling it 0-54 & 55-0 but that's what I had). I did this Many times with the same results.

Which were, once the arc initiated, it went immediately to 246A and stayed there. No matter what I changed or how I adjusted. This number, 246, became a crucial indicator. I got it to work properly, at random (once by just flipping the pedal upside down) and each time it worked, the maxed-out display would read 255 (not 246) BUT anytime it maxed-out at 246 that's all I got, as if the pedal was just a switch (caused me to replace the wire, which was a good move anyway, that cheap PVC wire was a pain in the cold too).

SO,,, it turns out, with all this testing and adjusting I was doing. I WAS NOT TIGHTENING THE COLLAR ON THE PEDAL PLUG. And that was causing, and creating the New trouble I was having. I would just plug it in and Test. I found that if I Wiggled that plug the display would go from 246 to 255 and it worked properly. If I Wiggled it just a TINY BIT loose then it read 246 and my pedal stopped working (the switch turned it ON, and the Arc was full the 246Amps).

Again, thanks for all the assistance. I now know a lot about my pedal I hope I've now got it "blueprinted" (I filed, lubed, adjusted, and even closed-up the plugs receptacle pins some) and won't have future problems with it.

The Only thing is, I simply can't get it to go below 24 Amps...


I currently have;

...........OFF...........FLOORED
3-4...0.5 Ohms......55.0K
4-5.....55.0K.........1.2 Ohms

The switch activates before any resistance changes. Any Ideas? I'd like to be able to go lower than 24A if I could.....

[performance]

If you are welding aluminum, the absolute minimum amps is 20 as it is spec'd for AC.