Power Pro 256 stuck at 240+ AMPS

[acannell]

First off, I'd like to make it clear I'm very happy with my welder and I would still recommend it to anyone who wants an outrageous bargain. If and when I have an excuse to buy another Everlast welder, I will.

So I was welding today and suddenly blew a hole through what I was working on.

I looked at the welder at it was at 257A. I had it set to 119A.

I tried flipping all the switches and messing around with stuff. The display stays at 257A no matter where I move the AMPS knob, except maybe the first 1/16th of a turn where it will go down to 240A. This is in TIG, PLASMA, and STICK modes.

I had a similar if not identical problem a few years ago and Ray at tech support sent me some parts and I was able to fix it following his instructions. So hopefully its that easy this time.

I called up Ray and he says that the display should be showing more like 400+A if the same chip that died a few years ago died again. Hrmm. I could swear that its doing the same thing it was a couple years ago.

The chip in question is the MC14053BCP on one of the daughter boards, and I believe the rework he had me do before (at my request) was replacing that chip with a socket and a new chip, adding a bypass cap to a resistor nearby, and replacing two diodes. I am an EE so soldering and troubleshooting is easier and quicker for me than packing up the welder and shipping it around. Technically its still under warranty right now, but if I can just replace a couple parts again that would be very preferable because I'm right in the middle of a project.

I just bought 4 MC14053BCP chips on ebay for about 6 bucks. I'm hoping this is the issue. I emailed Ray the control board number and hopefully he may have a few ideas about what I might be able to check to identify the problem if its not this.

Does anyone who has done a 4053 replacement remember the symptoms they had when it died? Did the current stick at full machine rated current or did it go way up to like 400A?

[performance]

Yeah, it would be going to 400 amps if it was that chip. My thoughts might be a bad foot pedal or foot pedal circuit. Have you tried it with the torch switch?

[acannell]

Yeah, it would be going to 400 amps if it was that chip. My thoughts might be a bad foot pedal or foot pedal circuit. Have you tried it with the torch switch?

thanks for the help!!

the display is stuck at 257 without the arc being turned on (no torch or foot switch depressed) Oh wait, so are you saying that the 400AMPs will show up only when the foot/torch switch is activated? Because I'm not checking that, I'm only checking what it says when its just idle. What should the display show when its idle if the 4053 is dead?

Can I just tap the torch/foot switch without letting the arc start (just pre flow) to see if the 400 shows up? I dont want to send 400A to the torch if I can avoid it

[performance]

A momentary surge won't hurt the torch...only burn up the tungsten. I'd check it with the pedal down. The 4053 could exhibit itself in several different ways IF I remember right, depending on what part of the chip fried.

[acannell]

A momentary surge won't hurt the torch...only burn up the tungsten. I'd check it with the pedal down. The 4053 could exhibit itself in several different ways IF I remember right, depending on what part of the chip fried.

Okay I'll give it a shot.

I was able to find my old email from a couple years ago where I had basically the same problem. Replacing the 4053 and adding the diodes and cap fixed it up until today. So I'm pretty hopeful that will fix it this time. The new 4053's are in the mail and I'll report back once I try them out.

Heres my old email:

"On 3/5/2012 12:32 AM:
Hello,

I had a serious problem with my PowerPro 256 today which makes it unusable. I have had the unit for about a year and a half.

This is not the first time I have used the welder. I have done maybe 120 minutes of welding with it (thats actual current ON time).

I was in DC TIG mode with pulse off, and using the foot pedal, doing simple welding on mild steel with a thin tungsten electrode (close to 1/16" diameter). I had just done a successful weld a few minutes before, and was starting a new weld. Suddenly a huge hole blew in the steel I was welding. I didnt know what had happened. I looked at the electrode and it was gone, it had vaporized about half an inch of the electrode. I looked at the welder and it said 130 amps. I figured somehow I must have set the current too high (I am pretty sure 130 amps would vaporize my electrode). I set the main knob back to 90 amps and tried again. A huge hole blew in the steel again and I let off the current quickly to avoid vaporizing the electrode again. The display on the welder now said 213 amps! A couple seconds later it went back to 90 (the usual delay).

I spent 10 minutes playing with all the knobs, switches, restarting the unit, etc.. but it would always say more than 200 amps once I pressed the footswitch. CUT mode shows between 245 to 257 amps regardless on knob position for amps.

I disconnected the foot switch and tried using the torch button in DC TIG mode again. The display would bounce around and sometimes say -1 or 0666.


"

[Rambozo]

.

I disconnected the foot switch and tried using the torch button in DC TIG mode again. The display would bounce around and sometimes say -1 or 0666.

Maybe your machine got possessed

[acannell]