- Thread starter ramadan47
- Start date
Hello and welcome to the Forum !
I think that your message was truncated, and will wait for you to complete the description of your problem.
In the meantime, from your picture of the two printed circuit boards I can see twisted white and red leads ( for gate and cathode? ) and six pulse transformers - so I guess this machine is a thyristor-controlled ( SCR ) 3-phase MIG welder.
In fact, that board looks similar to the one in this thread:
The fault that the current is either very high or very low could be due to incorrect feedback, probably from a current shunt or a Hall-effect sensor on one of the welder output busbars or wires, and connected by one of the plugs at the bottom of the left-hand board.
I think that your message was truncated, and will wait for you to complete the description of your problem.
In the meantime, from your picture of the two printed circuit boards I can see twisted white and red leads ( for gate and cathode? ) and six pulse transformers - so I guess this machine is a thyristor-controlled ( SCR ) 3-phase MIG welder.
In fact, that board looks similar to the one in this thread:
Silicone controlled thyristor board
Hi there!! I have fro mig 500 amp with dead motherboard, i want to replace main board to control arc lvl, anyone have ideas if this board can control silicone controlled thyristor input. board replacement: https://a.aliexpress.com/_mKrNCbQ
www.mig-welding.co.uk
The fault that the current is either very high or very low could be due to incorrect feedback, probably from a current shunt or a Hall-effect sensor on one of the welder output busbars or wires, and connected by one of the plugs at the bottom of the left-hand board.
thank yoy
Your second photo shows a large 3-phase transformer, and the PCB on the left side looks like a control board for an SCR controlled bridge rectifier. Therefore I think this is the inside of the welder DC power source.
However, the system uses a separate wire feed unit ( WFU ), and I guess the electronics that controls the wire speed is inside that box? If you move a failing WFU from one system to another, does the wire speed control fault transfer with the WFU ?
What voltage is the wirefeed motor? Does the speed control board monitor the motor rotation speed by an optical or magnetic speed sensor, or maybe via a tachogenerator?
However, the system uses a separate wire feed unit ( WFU ), and I guess the electronics that controls the wire speed is inside that box? If you move a failing WFU from one system to another, does the wire speed control fault transfer with the WFU ?
What voltage is the wirefeed motor? Does the speed control board monitor the motor rotation speed by an optical or magnetic speed sensor, or maybe via a tachogenerator?
