Re: [CAD_CAM_EDM_DRO] Step & Direction for Bridgeport Boss 3/4/5/6

Darrell wrote:

> Sorry to have to contradict you Jon, but the BOSS stepper drivers are
> very
> solid and reliable.

Well, I admit no personal experience with them, but I have seen so many
people
who use them say things like "oh, yeah, I have a drawer full of those
transistors,
and I replace one just about every week" that I believe this is true.
Also, I have
seen more than 4 people say that if you run into a stop, crash or
whatever, it
will pop a transistor with 100% certainty.

> I have several hundred machines retrofitted using the original drivers
> and
> they do not have problems. Further, if one did have a problem, they
> are very
> easy to fix.

This is probably true, if you know what you are doing and have the right
instruments
to test it, as it is quite simple.

>
> The bad press that the drivers have gotten is the fault of the control
>
> system that needs to be replaced.
> What happens is when the old BOSS controller makes any move over three
>
> inches a minute, it starts by jumping from dead stop to about three
> IPM and
> then ramps up to the programmed rate. At the end of the move it ramps
> down
> to about three IPM and then slams to a stop. The table or quill will
> try to
> keep going (inertia) which turns the stepper into a generator which
> puts a
> reverse voltage across the transistor. Transistors do not do well with
>
> reverse voltages.
> My control ramps all the way up and all the way down and I have many
> machines that have been running on the same set of transistors for
> over five
> years.

Ahh, so it is the BOSS control that wipes out the drivers!

> Oh, another reason that some people have trouble with their
> transistors is
> they got tired of paying a service tech and started buying from Radio
> Shack
> and doing their own repairs.

Yes, we had a big tape drive here, years ago, that the local service
people serviced
the same way. I got the correct Beryllium-Oxide heat conductors and
name-brand
transistors that the manufacturer used, and the drives stopped blowing
transistors
every week. You can't take Radio Shack parts and run them at 100% of
the rating
for very long.

> The BOSS drivers are rock solid and trouble free if you quit hitting
> them
> with a hammer.

VERY interesting info, here! Thanks,

Jon