iMIG-200 speed cal

[Rambozo]

I haven't had a chance to poke around inside to look for this, but is there a trim pot to calibrate the wire speed display on this machine?
I figure it is either measuring analog voltage to the drive motor or PWM duty cycle if that is what it uses for speed control. I just haven't had time to take measurements and examine the circuit. I would like to try and get it a little closer to reality, if possible.

[zoama]

I haven't had a chance to poke around inside to look for this, but is there a trim pot to calibrate the wire speed display on this machine? I figure it is either measuring analog voltage to the drive motor or PWM duty cycle if that is what it uses for speed control. I just haven't had time to take measurements and examine the circuit. I would like to try and get it a little closer to reality, if possible.

Mark says they increase voltage to the drive motor while welding. I have a tach that I was going to mount to read the actual wire speed while welding. I just haven't got around to it.

[Rambozo]

Mark says they increase voltage to the drive motor while welding. I have a tach that I was going to mount to read the actual wire speed while welding. I just haven't got around to it.

My error is the other direction. The display maxes out at around 280 but the actual wire speed is around 440. I'm used to just having a knob that goes from 1 to 10, but since it has a display, it would be fun to make it read a bit closer. I just marked the wire to get a rough idea of speed.

[performance]

Older model?

[Rambozo]

Older model?

A few years old.



Right on the display board was an intersil chip that is basically a voltmeter on a chip, LED driver and ADC all in one. It had a trimmer that got me in the ballpark. Didn't have time to do any testing, and I think that also changed the stick current display, but I doubt I'll ever use this as a CC supply. Next time I get a chance I'll see how linear it is and see about tweaking it better. There is a good datasheet on that IC so it should be pretty easy to get it sorted out. The wire speed pot can use a good cleaning or replacement before I spend anymore time getting it dialed in. If there is any technical data for this machine, I would love to see it.

Overall I'm really happy with the machine. Wasn't really in the market for another MIG, but it came along and I couldn't pass it up.

[performance]

Older models weren't cali rated ipm exactly. It was some logarythm. . Usually about 60 to 80 percent of wire feed.

[performance]

Sorry about typos. On my phone tonight.

[zoama]

A few years old. Wasn't really in the market for another MIG, but it came along and I couldn't pass it up.

You must've bought it from 225 with the upgraded gun.

[Rambozo]

You guessed it.