Thyristor 81RK100 Question

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Do I read this situation correctly?

A DC drive control board with ~200 components has worked, but has now failed (given its age it could be as simple as a bad electrolytic cap).

For reasons undefined, the control board is apparently not worth fixing, but designing its replacement with a simple circuit and an implied lack of knowledge of how to do so is being attempted?

If the circuit could be made simpler than what the OEM provided, why wouldn't the OEM have made it that way? Functionality? Reliability?

Methinks what's needed is a . . . . . Magic wand.

Are you available on a regular basis?

Many lost souls come here looking for a magic wand, or a miracle.

You give no useful information.

Look for a schematic on the web.

Send your defective board back to the manufacturer.

Buy a replacement board.

Have a service tech come on site and repair it.

#2 has it right, if you can't fix it.

Free rides are hard to get.

Buy a new Board. It will be cheaper because the new boards will be cheaper for the same power.

Trying to re-design the drive will take time and a lot of trials for someone who had no prfesional experience in the field. This will cost more than to prchase a ready made new drive for the purpose: What dc motor (or else?) is it driving, and the power required ....

From your brief description and the photo (the photo shows three gate drive pulse transformers on the left) that this is the control board to a three phase phase controlled bridge rectifier that probably has three SCRs and three (or four) diodes.

Having a gate drive circuit to turn on the thyristor is only a portion of the solution. The bigger problem is the control logic which tells the driver when to fire the gate drivers and when to hold them off. This gate drive board probably has circuitry to hold off the gate drives when the system is powering up and down

I agree with others. The best solution is to fix the old control board. It looks as if this is a two sided circuit board so that the circuitry can be easily reverse engineered and documented in schematic diagram. If fixing the old board is beyond your capabilities, so is designing a replacement.