I've got a Bridgeport Series 1 Boss 4 that I am converting to PC control using the HillBilly BOB. The X axis works like a champ (I am using Mach 3 and driving the stock steppers using the stock BP drives). The Y and Z axes will not move. So far I have checked my 56 and 24 volt power, the ACC board, and I have compared and swapped all 3 of my SMD boards. I have also checked the SMS board. I am running out of things other than checking for broken wires. Can anyone recommend something else to check? Maybe a stepper test?

Thanks,
Mark

Check the output transistor banks. They are under the plug in boards (SMD's & ACC) mounted on the heat sink.

Darek

Darek,
Thanks for the reply. I will have to check those. Is that a common failure? There's a bunch of those....

Mark

Yes very common failure. Take off the covers of your y and z and see if the motors have holding torque or if they spin freely with the machine on. If they have holding torque then its probably a transistor. You can also fry the transistors on the ACC board so check those too to be sure.

May be too simple but have you checked to make sure that the BOB is pulsing the driver? (are the leds flashing on and off when you jog the y or z through mach?) If not make sure they are enabled in mach and that you have your pin assignments correct.

good luck
Matt

http://www.cnczone.com/forums/search.php?searchid=835106

Matt,
Thanks for the additional data. I have checked and the board is pulsing on all 3 axes as it is supposed to. I have already checked all of the transistors on the ACC board. They match. Also, I have flipped the ACC board upside down ( a trick in the BP Manual) and the problem stays the same.
The link you posted in your second thread didn't work for me.

Thanks,
Mark

My experience has been if you are blowing outputs more than every year or two something is probable wrong.

Some things to check would be:

1. Current setting for the axis.
2. The connections between the drive and motor
3. Machine ground
4. Chips in the electricl cabinet.

Darek

Mark

The link was to a search of the site for "bridgeport transistor" There are about a dozen threads detailing the things you should check etc. It will provide alot of information that I honestly haven't ever done so I can't properly advise you on how to do it. Such as: checking and adjusting the current to the drive.

You haven't said yet if the motor has holding torque but won't step or if it is completely dead.

You have checked all of these transistors:
ACC board
SMD Boards
Final drive transistors mounted on the heat sink.

If you fire up the machine and in mach tell one of the axes to go somewhere really slowly (1ipm) or something then you will have several minutes of pulses to the drive circuit to poke around with a DMM and see where power is getting to. Once you stop seeing voltage switching on and off, you have found your problem.

Matt

As a follow-up to my question- Thanks for all of the advice. When I dug further into the control cabinet door, I found 5 bad transistors on my Y and Z axes. Here are some pics that will hopefully help someone who is having the same problem that I had. One is a shot of what the control cabinet back door looks like with all of the SMD boards removed. The next is a shot of the back side of the group of axis driver transistors.

Thanks Again,
Mark

Hi

In your last picture it looks like the diodes are all missing on the X axis final drive transistors, might just be a bad picture though.

Chris

There weren't any on the X axis. There were diodes on y and z though. Ironically, my x axis worked and y and z didn't

Mark