@RoyBoy posted:It might not be too late to get a replacement loco. Have you contacted Menards via email?
They were very good about replacing my 3.5 when it conked out, but that was a month or two ago.
My symptoms were different than yours, but possibly caused by the same/similar board failure.
Mine ran fine one day and then the next day it would not run at all. I disconnected the motors and hooked up an incandescent light to the board's motor outputs. The light lit when commanding the loco to run forward or backward, showing me that the logic was good. But the motors did not turn when hooking them to the board. The motors were OK when running them from a separate power supply.
Anyway, you might contact them. Ray was the fellow I communicated with. He was very helpful.
Per the data sheet of the motor driver H-bridge. https://www.allegromicro.com/%...A4950-Datasheet.ashx
"Full-Bridge DMOS PWM Motor DriverA4950
FUNCTIONAL DESCRIPTION
Overcurrent Protection
A current monitor will protect the IC from damage due to output
shorts. If a short is detected, the IC will latch the fault and disable
the outputs. The fault latch can only be cleared by coming out of
Low Power Standby mode or by cycling the power to VBB. Dur-
ing OCP events, Absolute Maximum Ratings may be exceeded
for a short period of time before the device latches.
Rs is RS1, R110= 0.11 Ohms
I measured Vref and it is exactly 3.5V
3.5/1.1=3.182A I tripMAX
So, if your motor(s) draw higher than 3.2A then you might invoke "the IC will latch the fault and disable the outputs".
Possibly not a board failure, but could be a motor failure -example oil contaminated commutator clumping the slots with brush material causing high amperage.
