Re: Bridgeport boss 4 Spindle not powering up (continued)

According to rigger <dgrup@xxxxxxx>:
DoN. Nichols wrote:
According to jak <jakdog@xxxxxxxxx>:
Thanks for the helpful suggestions regarding my Boss 4 spindle not
powering up problem. Here is some more information:

[ ... ]

So I hope this is enough info for some saint out there to help me out,
I really don't want to call inthe $100 tech.

We're *trying*. But it is rather difficult to do a good job of
troubleshooting something this complex at a distance, when you are
having difficult identifying the various parts about which we are
asking.

Note that this also depends on the proper relays being in the
sockets in the base of the computer chassis on the right side of the
machine (as viewed from the front). And -- if a safety fix has been
installed, you need to reset a safety interlock on the motor switch pod
to confirm that you have changed the tool and have your hands safely
clear again -- *each* time the system thinks that a tool needs changing,
which probably includes when it boots up.

Have you ever seen this operate? If not, you may not know how
to reset the CPU on initial power on.

[ ... ]

Good ideas DoN. I was hoping someone with more specific information
would show up to help jak. I can work my way through the average power
circuits but there's sure nothing like hands-on experience.

My experience is with a BOSS-3 (old enough so the logic cards
were wire-wrapped, not custom PC cards. :-) But the basic principles are
the same, though the power supplies change a bit.

I think jak will be ok on things like relays and logic boards because,
during the first series of this topic, he said when he tried to
activate the spindle all he would get would be a buzzing sound. Also I
understand there are two mechanically interlocked contactors for the
spindle. So, if I understand the circuit correctly, all of the rest of
the circuitry is used for control; which kind of leaves us with a power
problem.

However IHBKTBW.

On the other hand I worry a little bit about that fan problem.

On mine, there were two muffin fans (24 VDC, IIRC, though they
might have been 230 VAC instead) mounted in the bottom of the logic cage
-- where they were very difficult to get to and replace. Both were
gummed enough so they did not run.

In the
past I've seen things like a fan set off a chain reaction, which in the
case of this type of electrical system where you have a TON of power
conversion (in a relatively small enclosure),

Not really much power conversion going in in the big back box.
The three-phase transformer was connected to three bridge rectifiers
(one per phase, each for a different axis stepper motor drive). In
series with the AC feed from the transformer to the rectifier is a
saturable reactor (transformer whose AC impedance is changed by DC
through the other winding saturating the core), which is used to reduce
or increase the voltage actually reaching the bridge rectifiers -- on an
axis-by-axis basis. None of this dissipates much power, unlike trying
to control that much current (7A per stepper) with transistors of the
day.

The logic cage on the side includes a hinged back door which is
a large heat sink loaded with transistors to drive the steppers. The
drive boards are in a smaller card cage in the logic cage, and are
eventually driven with TTL level signals. The CPU is a quad-wide LSI-11
with custom firmware. The whole thing could be replaced with a lot more
power efficient circuitry these days.

would be the effect that
much heat would have on other components in the box.

Pretty much everything in the back box is pretty immune to heat
problems. Even the filter capacitors are moved to the logic box
instead. The interlocking three-phase contactors to control the spindle
motor, and the heat coil assembly which accompanies it are in a third
box (which he showed in a separate photo. In the bottom front of the
box is (maybe) an optional AC outlet to power a coolant pump, and to
power a work light.

I *think* that box has enough room to accept the Mitsubishi VFD,
which will let me control spindle speed and direction with logic
signals -- and eliminate the contactor entirely. The later models than
mine have a compressed-air powered motor which turns the variable speed
pulley crank, and an air solenoid to operate the spindle brake. Mine
does not have those.

I'm guessing a
little here because I have no way of knowing if the fan and spindle are
powered by inter-related circuits which could mean when you fix the
spindle problem the fan will run.

Since the commands to the spindle contactors are derived from
the logic circuitry, plus a panic switch in the motor switch box, all
the logic and relay power must be working before the contactors will
pull in. And -- the CPU has to be in a properly booted state. IIRC, it
needs to be reset using some small switches in the top half of the logic
cabinet -- which may or may not have a punched tape reader in there as
well.

dennis
in nca

p.s. Hey jac. Are you doing the voltage measurements at the motor and
while someone is holding down the motor start switch? Or are you
holding in the contactor mechanically?

The motor start switch is held down by the CPU, not by a person.
And the direction is selected by a switch on a pod just beside the
motor, along with the panic switch. (Mine was missing the panic switch,
and I had to replace it with one which I could get, plus a relay to
provide enough contacts to duplicate the switching of the missing
original panic switch.

Enjoy,
DoN.

--
Email: <dnichols@xxxxxxxxxxx> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
.

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