Miller STH 160 pedal problem

[Pietzeekoe]

Hello,

I recently got a Miller STH 160 and I made a pedal for it. It's all wired up correctly but the machine doesn't seem to recognize it. The Miller STH 160 has a "pixel" on its seven segment display that will light up when it sees a remote. My machine doesn't see the pedal when I plug it in. Is there a setting I need to change to switch over to pedal control? Does anyone have any experience with the Miller STH 160 and pedals?

Thanks!

 

[Tigman]

apparently you can reset the machine to default by turning on and off while pressing and holding the process button, this may reset your machine to recognise the pedal !

 

[Maker]

Are you absolutely your pedal isn't wired up wrong?

 

[Tigman]

it says in the manual to plug in the remote before you switch on , allow time for startup sequence and the pixel should flash !

 

[hotrodder]

Many machines have a local (panel) and remote (foot pedal etc) button but a quick scan of the manual suggests the only relevant setting is that's in TIG mode and it'll work out whether you're using an on/off momentary button or a foot pedal. If

it says in the manual to plug in the remote before you switch on , allow time for startup sequence and the pixel should flash !

this doesn't fix things then it's time to tell us more about the pedal you made... is the pot definately the correct value (1K ohm IIRC)? Is the contactor (pins 1 and 2) done with a seperate momentary micro switch or are you using a pot with a built in switch?

 

[Pietzeekoe]

is the pot definately the correct value (1K ohm IIRC)? Is the contactor (pins 1 and 2) done with a seperate momentary micro switch or are you using a pot with a built in switch?

The contactor is done with a seperate switch and the arc initiation does work, the current adjustment doesn't however. The pot I used is a 50k pot, but the resistance is irrelevent since it' s set up as a voltage divider. I'll make some photo and a schematic when I get home.

 

[hotrodder]

While pot values may be irrelevent for many applications it's not in this case... if you buy an SSC foot pedal or a CK thumb remote or whatever it's not only the plug that differs between brands of welders, buy one for a Miller for example and it will have a 1k ohm pot in it while for a Lincoln it will be 10k ohm. There may be some machines about that don't really care but when the machine 'automatically recognises' the remote control it's gonna be looking at more than just the voltage difference...

 

[Maker]

I wouldn't be surprised if the welder measures the resistance across the two outside pins (Not the wiper) to check there's a pedal attached; with your resistance being so much higher than it expects, it will think there is no pedal attached.

Try attaching a 1K resistor across those pins to see if it says there's a pedal attached or not. Your pedal won't work with the resistor there but it will confirm that you need a smaller potentiometer if the light does come on.

 

[Pietzeekoe]

I found a schematic in the back of the manual showing a remote connected. It shows a 10k pot. I happened to have a 10k pot laying around. I soldered it in, nothing...still the same problem. Contactor works, display doesn't show the "remote pixel" and I can't adjust the welding current. Feeling down on my luck I connected a 1k resistor across the two opposite pot terminals and the remote pixel started flashing! Miller screwed up the pot value in their schematic.

You guys are freaking amazing, thanks!

 

[hotrodder]

I don't think many people bother when making themselves a pedal or having a cheapnese knock made to sell under their brand but FWIW (and as you need to go shopping for a pot anyway) the OEM Miller pedals and SSC pedals* all use decoupling/smoothing capacitors. They're in the exploded drawing/part # lists at the bottom of http://www.millerwelds.com/om/o844e_mil.pdf and http://www.millerwelds.com/om/o844b_mil.pdf If you google the Miller part # you get http://www.brweldingsupplies.com/miller-249583-capacitor-cer-disc-1-uf-500-vdc/

*can't see the caps as they're taped up to the wiring sleeve but the tails are just visible here http://www.mig-welding.co.uk/forum/threads/non-r-tech-foot-pedal.47212/#post-539212

 

[Pietzeekoe]

the OEM Miller pedals and SSC pedals* all use decoupling/smoothing capacitors.

Ah, thanks. I will definatly add some of those while I'm at it.