Silicone controlled thyristor board

[xdevgame]

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:

80.2￡ 7% OFF|Silicon Controlled Thyristor Voltage Stabilizer/current Stabilizer Three phase Phase shift Single Closed loop Trigger Board| | - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

 

[eddie49]

Hello, and welcome to the Forum !

I think that you have made a good find with that replacement SCR/thyristor control board, which looks quite technically competent. It uses pulse transformers to trigger the SCRs. There are 12 output terminals, to connect with the gates and cathodes of 6 SCRs.

Are the SCRs in your welder used as power control for the three primaries of the transformer, or in a controlled 3-phase bridge rectifier on the secondary? Looking at the size of the conductors in your photograph, I think it is the latter - i.e. they are on the secondary side. These two scenarios are shown as "Voltage stabilizer" wiring diagrams 1 and 2 in the AliExpress description.

The SCRs in your welder are very large, so you would need to ensure that the trigger voltage, pulse duration and drive current provided by this replacement board are compatible with your SCRs.

On the input side, the board accepts voltage feedback and uses a 0-to-10v DC level to adjust the triggering phase-angle delay. This signal will control the welding power, and you would have to build a potentiometer circuit to provide it.

This replacement board can only manage the output power, you still need on/off, gas valve, and wirefeed motor controls.
The existing failed motherboard may also have functions such as burnback delay, and spot or stitch welding timers. Would it be possible, and maybe easier, to repair the fault on that original board?