Bob T said:
There are two boards each with different symptoms
#1 has the drive such that the wheel pulled hard left
I suspect a blown op amp opa541
the second jumps around when nothing should be happening intermittent
I swapped the boards between machines and the problems followed. No
obvious memory parts on the boards to I think I have some analog or drive
problems
These machines were both bought recently and haven't worked since they
were delivered so I suspected the usual broken or hairline cracks on
electrolytic caps but found nothing
Start by checking the output devices, a shorted transistor in an H bridge
will cause the motor to pull hard one direction. If you suspect an op-amp is
bad, replace it, they're cheap, you can always desolder specific pins to
isolate sections of the circuit and work your way back.
The jumping around randomly can be a lot harder to track down. Are you sure
no decoupling capacitors got knocked off? Those can cause all sorts of
gremlins.
