in the midst of upgrading my machine to mach via hillbilly BOB, i crashed the x axis. long story but i tried to make the ball screw go farther than it can. initially it still worked as i moved it back the other way after my crash. then it would no longer move.
I found that the AC side x axis fuse was blown.
Replaced it with the fuse out of the y axis (no spare on hand).
Now x shows symptoms of a shorted transistor, this is about the time I smell magic smoke(quickly shut off machine).
After poking around i found that the x resistor on my sms board looks like it got smoked.
I checked around in the power cabinet and found the power resistor on the saturable core reactor had one leg either broken off or had come out of the terminal. I put the lead back in the terminal and screwed it down.
I took out the transistor block and located a shorted transistor.
I will be replacing the transistors and the sms board resistor along with the diode. The SMS board fuse never blew. should it have? what is the proper rating for that fuse?
I have seen reference to "frying" boards. ACC and SMS.
What components on the ACC should I check for "frying"?
It is quite obvious I fried the x portion of the SMS.
Is there anything else I should check before powering up again?

Thanks in advance for any insight you may share
Matt

Unfortunately I have seen this many times. You have found the source of your problem I think. I am not familiar with your conversion and how it interlaces with the original components.
Usually the power resistor fails on a saturable core reactor (I replace them when I see cracks on them, especially the underside surface with resistors of twice the wattage). This causes the SMS fuse to blow, the corresponding resistor on the SMS to fry, and if not caught fast, the corresponding transistor on the ACC has the solder melt out and the board fries from the heat. Thus check all these components.
A transistor blows when it is shut off. Especially when an axis is moving and you press Emergency stop or hit the end of travel/limit switch.

George

Thank you sir

As always your expertise is appreciated.

The hillbilly mach setup uses mach to drive the acc board instead of the XDI. from the acc on its all stock.



Thanks
Matt

I also have an axis problem. I am setting up a new Boss 4 system with the HillBilly BOB. It should be no surprise that my Z axis doesn't work. Could someone please tell me what components I should replace here to be safe? Obviously R10 and R32 are cooked, but it begs the question of why. I check Q4 and it looks OK. Thanks for any input on this.

Mark

This is what happens on the rare occasion a output transistor opens instead of shorting. R10,22,32 & 44 on the SMD boards are the emitter resistors for the predriver of the output. If a output transistor opens (Q1) Then the current path shifts from the output emitter resistor (R1) to the predriver emitter resistor (R22). This takes some time to happen after the output opens.

Replace them with flame proof resistors and elevate them off the board.

The user base keeps growing!!!

Darek






Darek