In article ,
Ignoramus24760 wrote:

On 2010-08-30, Joseph Gwinn wrote:
In article ,
Jon Elson wrote:

Ignoramus5734 wrote:
That was am AMC 30A8 amplifier, revision T.

The chips on them mostly do not have markings, this one was a small
one in the middle of the motherboard.

I really like the drives, their simplicity, cost and support from
AMC. I do not know if I can guess the cause. But, possibly,
interference again is to blame.

VERY unlikely.

Agree.


You mentioned ferrite cores to place on these cables. Would you
suggest any particular Digikey part number?

Sorry, I really don't have a part number. You might check old computer
cables for those
bulges in them, those are big ferrite rings for noise isolation. You
want to run both
motor cables through the same core, so they are not exposed to the motor
current
(the current in the two wires cancels out).

The split-sleeve emi-filter chokes are what Iggy seeks. Here is an
example:

http://search.digikey.com/scripts/Dk...me=240-2131-ND



However, these chokes really are not that effective compared to real
shielding.
I would first shield the motor power leads, as they are very high power.

Joe, I bought those rings. I will shield the wires going to the big
terminal block from the drives, (and ground the shield) and would put
the rings on the wires going out of the terminal block to the motors.

Cheap enough to just try. One normally puts all three (or four) motor leads
through the same core, so the power-frequency magnetic fields largely cancel, to
avoid magnetic saturation of the ferrite. One can put multiple cores on the
same cable, one after another. Nor will anything bad or permanent happen if you
do put a single wire through a core, perhaps saturating the ferrite, so there is
no reason not to try everything.

Joe Gwinn