Help with Board

[ignatz]

Hi All,

I am really stuck here and could use your help. I have a 4 axis kit. I am in the process of testing it now. Here's a quick re-cap of what's happened so far:

(Were working = Able to Jog with TurboCNC)

1. X,Y,A were working. Z was not. Began Blowing 4A fuses. Getting
0VDC with no board attached.

2. Traced problem to a bad solder joint from the fuse to the transformer.
Began testing again. Y was working. Z was not. When I used the jog
command for X (and A) I saw an arc on the driver side of the heat sink and then both motors went silent.

3. I tested the voltage at X, Z and A = 0.541, Y = 0.540.

4. Currently, the only working axis is Y. I am fairly certain that the motors on the other axises are fine but I haven't moved them to the Y axis to be sure.

Is this reading high enough to fry the driver chips? If so, where can I obtain a new chip? (I know that I can order one from HobbyCNC but I'm hoping to use a vendor with shipping options other than the Post Office)

Is there another test I can do to determine if the chips are
good or not?

Finally, I set the voltage to 0.540 initially. Should I have used a
different value?

[ignatz]

I've just finished going over the board and now
both the Y and Z axises work with all of the steppers. The driver
chips for both A and X have large holes in the numbered side near the
right hand edge, so I'll need a couple of new chips.

What could cause this sort of damage? Both axises worked at one
point. There were no solder bridges on the bottom side of the X or A
axis. The arcs were on top of the board.

Any advice is much appreciated.