Re: [CAD_CAM_EDM_DRO] My broken Briddgeport

kuchean wrote:

> I have owned a second-hand Bridgeport V2XT for over a year without
> being able to run it! Somewhere in that large box of old electronics
> hanging on the side something is f%^ed up and I would like to be able
> to identify what is wrong before either ripping it all out or trying
> to unload the thing at a big loss.
>
> After some playing around I have been able to get the computer, an
> old 286 to boot up. Trying to start the machine results in an error
> message that says I have drive failure on all axis. I shipped one
> amplifier board to EMI and they say it tests out fine. I suspect the
> other two boards also work just as well. Indications are thar the
> servos are also alright. The fault which may be a loose cable or a
> blown fuse or a bad BMDC board is between the computer motherboard
> and the servo boards.
>
> It is far past the time when have to deceide to "piss or get of the
> pot". With all those blinking LEDs in there something should be
> indicating the source of the problem! Since the machine was bought
> for home use I am reluctant to put more kilobucks into it.
>
> Eventually I know I will have to replace a lot of the silicon in the
> thing, but what is the path of least cost to get the machine problem
> diagnosed and patched if not finally fixed?

Without a lot of electronic expertise, it is pretty hard to locate a
problem like this. Since there is good reason to believe the
servo amps are actually OK, then a retrofit is a good plan.
Actually fixing the existing control just to know what the exact problem
is may be a poor plan, as you have no way to know when the next
breakdown will happen. And, it may be impossible to locate the
problem without fixing it.

Of course, it could be just a broken wire, or some external piece of
gear that was disconnected. Most of these systems have what is called
a "fault chain", which is a bunch of normally-closed contacts wired
in series. If any one of the contacts opens, it breaks the chain, and
causes a fault condition, but the control can't know exactly which
contact caused the fault. There are often door interlocks and emergency
stop switches that cause this to happen, too. So, check all the interlocks,

auto-lube pump level, air pressure switch if so equipped, servo amp
power supply, etc. Anything that could have a fault sensor tied to it
could be the cause. The message "drive failure on all axes" may be
somewhat imprecise, just meaning that one or more axes show a fault.
It may also mean that the servo amp power source is not coming on.

Jon