dgrant Posted December 9, 2023 Report Share Posted December 9, 2023 Someone brought me a 4203 838B for troubleshooting. What I find is the mag base works good until the motor FWD or RWD is pushed. The mag base light will go from steady on to flashing. The more important failure is that the actual drill motor starts to run in the selected direction but quickly stops. Its a case of the power relay(s) closing connection then immediately opening back up. You can actually hear the relays doing just that, closing then immediately opening. This is a 4-wire drill motor. Black/White/Red/Blue wires. I suspect the motor full control and card is the probable cause of this failure but not positive. There isn't a lot more to it. Now for the motor's blue and red wires, not sure what they are for. Obviously this is a reversible motor so one of those wires is probably related to that. What I cannot find anywhere is a formal schematic to the control board. Unfortunately, Milwaukee epoxied the circuit board totally so there's no getting to the components otherwise I could reverse engineer it and possibly locate the issue. I suspect the "softstart" function that's supposedly built into it. Thoughts, ideas, help? Quote Link to comment Share on other sites More sharing options...
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