Thermal Arc Fabricator 250

[Bweld]

Hi folks, new to here and looking for some collective knowledge on a problem…
I have a Fabricator 250 which I can’t get wire speed to go past around halfway. Tried all the obvious things I think! and have swapped wire feed motor with another unit and also wire speed control switch. Wire speeds up as you turn dial but around halfway maxes out at a lot slower than it should be. Voltage going to wire feed motor goes up to around 13.5 volts then stops, I assume as it’s a 24v motor it should go nearer to 24v when at full speed? Any thoughts welcome!
Thanks

 

[eddie49]

Hello and welcome to the Forum!

This earlier thread on the Fabricator 250, whilst lacking a conclusion, should provide some some useful information:

H

Thread 'Thermal arc 250 Fabricator fault finding'

Feb 18, 2025

Hi there,

I am fault finding a welding set for a family member, at first the set was not doing anything but I found the neutral or common going to the isolating transformer was 240v down to earth. I have disconnected the three cores of the cooling fan to temporary fix this issue. for some reason the fan has 250v on all three cores which is strange but I have disconnected this completely to continue fault finding the low power output. after this the machine is arcing away like it should but with low power.

I've been using ChatGPT to assist me and it is recommending check the following...

• horsey89
• Replies: 6
• forum: Migatronic, Thermal Arc

The first photo shows the control printed circuit board. There are three power semiconductors with heatsinks, and also two large diodes near the left-hand white plug. This implies that the motor speed controller consists of two thyristors ( SCRs ) and two diodes, forming a half-controlled bridge rectifier. The third semiconductor is probably another thyristor, triggered to short the motor and bring it to a rapid stop.

The motor is 24v DC, and the supply into the controlled rectifier will be about 24v AC. From that thread, there is some doubt as to where this supply comes from - maybe a medium-sized auxiliary transformer, or perhaps from a strange second winding on the cooling fan!

The fault on your machine may be in the circuit on the PCB that generates the control pulses for the thyristors, but I would start by checking the AC voltage outputs at the auxiliary transformer ( if it exists ), and at the "third terminal" of the fan.