Help! Bridgeport Series 1 CNC Y travel not working

[jairosoft]

Can anyone help me? We have a beautifully repainted Series 1 CNC viewable at http://www.kiselectro.com/irdem/precisionmachinery.html and everything works fine. All the motors work. The Y axis motion does not work and I suspect it is the ACC board which looks like it controls all three directions. The part num is stamped AC18568 and a big 5 followed by a SN 2568. Anyway the other three boards that are exactly alike and interchangeable seem to be okay as I can swap them and they work. But this ACC board is key to all the three. Does anybody have schematics to this machine? Thanks for your help. call me at 407-923-4027

[Wilabee]

Hi,

I have owned a Series One, with Boss4 control, for 10+ years. When I have an axis that will not move, or "groans" in the jog mode, the problem is almost always a shorted axis power transistor. There are four power transistors per axis. They are located "out of sight" behind large extruded heat sinks behind, and slightly above, the ACC and SMD boards which are mounted in the control door in the rear of the machine. My method of repair is as follows:

1) Remove the ACC and SMD boards.

2) Locate the heat sink for the problem axis and carefully loosen/remove the screws in the terminal strip mounted on the heat sink.

3) Using a long "allen" wrench or a "allen" tee wrench, carefully remove the 8-10 socket head cap screws that hold the heat sink to the door. Use caution, as the screws will fall off the end of the wrench and disappear somewhere inside the door.

4) Remove the entire heat sink assembly.

5) Check for a shorted transistor with an ohm meter. (the transistors are rather large with a metal case)

6) Remove and replace the defective transister. (easier said then done!) Be sure to replace the mica insulator under the base of the transistor.

7) Re-install the assembly inside the door. (be sure to put some of that white conducting goop on the back of heat sink before installing.)

8) Re-attach all of the leads to the terminal block.

9) Proceed with the "smoke test" (ie: cross your fingers and turn the power ON!)

10) Try jogging the axis.

Good Luck, I hope that this solves your problem.

[machintek]

Enable drives, put it in SETUP, JOG STEP< Y axis. Press the +/- motion switch. Watch the mechanical counter. Each time you press it, it should move the mechanical counter a division. A shorted transistor will create a situation that it will move forward a few steps and then backward. If trying to jog in a continous method, the axis will not move but will whine. If no whine and movement, check the AC axis fuses in the back cabinet and the DC fuses in the side cabinet. A blown fuse may indicate a shorted bridge rectifier. If a blown transistor, follow the above excellent procedure.

Get a manual on CDrom at machinemanuals.net.

George

[jairosoft]

Thanks so much Wilabee and Machintek. I haven't had a chance to try out your suggestions yet. But when I get to it I will tell you what happens. Wish me luck.
Bye,
Jairo