Control questions on the new Powermaster 205

Hi,

I spent the weekend setting up my new PM205. Since the user manual was written for the older design, I have had to make a few guesses on what the controls do.

As far as I can tell, the Pulse current knob sets the peak current, and the foot pedal knob controls the base current limit. With the pedal, you can control the base current from some minimum number up to the limit that you set with the knob on the pedal. Is this true? (It is hard to weld and watch the current readout at the same time!). If so, is the knob on the foot pedal a 0-100% scale of the Pulse current setting, or some absolute (like 10-200A)?

If you are not using the foot pedal, how do you set the base current?

Lastly, AC welding aluminum felt 'agressive'. Is there a minimum thickness of Al that this machine is capable of?

thanks,
casey

The pulse is primarily intended for using only with the panel controls. It is difficult to accurately set the pulse with the foot pedal, since it is continously variable. When you are using the pedal, on any machine, you are not getting an accurate setting of amperage, so attempting setting the machine on pulse is sort of a moot point. You can get a ratio, but it is contiously variable.

The foot pedal knob controls a percentage of 200 amps, at least that is the way it was spec'd. I haven't used one yet to confirm the exact operation.

The main current knob is your base current control.

AC current IS aggressive. That's the nature of it. You can adjust frequency and balance to fine tune the arc, and of course you can reduce the main amperage. But sheet aluminum should be no problem as minimum amperage can be set to 5 amps.

Hi Mark,

I am afraid your response confuses me even more.

The Pulse control knob on the unit sets the base or the peak current limit? What controls the other (base or peak)?

The knob on the pedal sets the peak current? Does the pedal (the actual pedal not the knob) control the base or the peak?

Could you please provide me with a recommend use procedure? Say I want to pulse with 130 A peak and 30 A base. What knobs do I turn?

casey

Ok,
Lets back up and punt on this one.

The following picture is of the two amperage controls concerned with setting pulse function using panel control. The main knob is your base current control/main amperage control. This is what the display should read on the unit when you adjust the knob. The pulse current and base current should cycle back and forth on the display when pulse is in operation.

Now, as I said, the pulse operation is not the best choice for foot control. You are varying the amount of base current/peak current control. To use this properly, you will need to turn the peak current down or to the left most position to eliminate its function.


The knob on the foot pedal limits the base amperage to a percentage of the full 200 amps. It is a rheostat. That is what rheostats do. You pedal functions within the range of what the rheostat allows for base current. If you have the rheostat knob on the pedal at the mid 50% mark, then that means that the maximum current you will get from the foot pedal, wide open is 100 amps for base current. Unless something has changed, the peak current is not tied to the foot pedal on this model. On the 256, you are dealing with ratios and percent so that the foot pedal varies the amount of both peak and base currents in proportion.

This type setup for pulse control with a foot pedal is not an exact science. You will need to observe the current wide open to see what the foot pedal max is. This is our economical unit and does not have the same precise settings as you are demanding. The 256 has full control and function through the settings with the pulse set as a ratio so that proportional control can be maintained with the foot pedal. But as I said, the foot pedal is not typically used with most pulse systems. The panel controls are designed for pulse use and for the down slope and post flow adjustability through the use of 2t/4t.

Here is the picture.

I recently purchased a PM205 from you as well, and I have questions of a similar nature. Is the knob on the foot pedal tied to the red main amperage knob on the machine? For example, if I were to set the knob on the machine to 100 amps, and the pedal to 5, would I get 50% of 100 amps, or would I get 50% of 205 amps?

I also have a problem with getting any adjustment whatsoever with the pedal itself. It seems to make no difference if it's mashed or just slightly pressed. Even turning the rheostat by hand doesn't make a noticeable difference. The rack gear on the pedal had slipped off to the side of the gear on the rheostat, but I put it back on with the rheostat set to all the way in. Does it need to be somewhere in the middle of its range to work?

On the 205, your secondary rheostat on your pedal is in full control of the amperage. The panel control does not affect foot pedal control. As I believe I have mentioned before, the 205 is our economy model and that is how it is regulated. The PM 256 is regulated through the panel control and there is not an additional rheostat on the foot pedal.

It is possible that the pedal cog is loose. Mike can give you further details if need be.

Thanks, I think I have it figured out now. I even ran it in 4 step mode using only panel settings. I like being able to start and stop with just the torch, that's going to work out nice on awkwardly positioned stuff, when the foot pedal is hard to use.