Recommendations for stepper motor debug / repair

[john swift]

not sure how many companies like MASSEY COGGINS LIMITED in liverpool that rewound motors are still in business these days

I expect too many potential customers bought new chinese motors instead of spending as much (if not more) on a rewind

cables that are constantly are being flexed very often break just after a connector or clamp

breaking the current through an inductive load like a motor produces a large back emf that is likely to damage any semiconductor its connected to

after repeated replacement of the fuse its likely that either a transistor or the current sense resistor is now become open circuit

for example if you look at figure 12 on page 14 of the data sheet of the L6208 H bridge


the pairs of FET's H1 & L1 or H2 & L2 must never be on at the same time only as that will short circuit the supply

one FET from different pairs can be on
eg H1 & L2 or H2 & L1

if a FET goes short circuit
the current sense resistor connecting FET's L1 & L2 to the negative supply can go open circuit

John