21 Jun
2007
21 Jun
'07
4:08 a.m.
Subject: RE: NorthStar Horizon Case Cover Replacements
From: "Chuck Guzis" <cclist at sydex.com>
Date: Wed, 20 Jun 2007 13:56:02 -0700
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
On 20 Jun 2007 at 8:49, Allison wrote:
> What made the box notable was floppies in the crate rather than external
> box and only a LED (power on) on the front pannel. It was one of the early
> turnkey systems and became popular with applications/system integrators
> for that reason. The reason being it was now possible to sell a small(then)
> system that was powerful enough to be a complete office accounting system.
> It didn't hurt that the wood cover fit into office decor of the time.
> The wood disappeard when FCC started forcing RFI constraints.
By RFI I mean the kind of interferfence from the disgital switching action
that could blanket communications bands.
There was a good reason for that. A friend had
purchased one of the
Integrand S-100 boxes with a floppy cutout. He'd installed an SA-400
(IIRC) and complained that it wouldn't work reliably. What I
discovered was that the field from the large power transformer was
playing hob with the drive electronics. I installed a substantial
steel shield around the floppy and the problem abated.
NS* Horizon never had a transformer magnetic field problem. And the drives
are only a few inches from the transformer.
The problem may have been the CVC transfomer used in some Integrand boxes.
Those radiate a larger magnetic field.
When I purchased my own Integrand box, I opted for the drive-less
model.
Even on the Durango box, we had to shield both the drives and the
small monitor that sat over them to get reliable drive operation.
I have an NS* Advantage and they also apparently did it right as the drives
behave well without steel shield plates.
Allison
Cheers,
Chuck
21 Jun
21 Jun
8:56 a.m.
Orientation of the drive with respect to the power transformer on the
Integrand was important. Changing the position by 90 degrees offered
a substantial improvement, but that wasn't an option, as the panel
was delivered pre-cut for a drive.
On 21 Jun 2007 at 7:08, Allison wrote:
I have an NS* Advantage and they also apparently did
it right as the drives
behave well without steel shield plates.
It could be that some drives are more sensitive to this sort of thing
than others--and that some monitors orient components in exactly the
wrong way. In the case of the Durango, the monitor was a small 9"
Ball Brothers OEM model and the drives were Micropolis 100 TPI
models.
The large carriage stepper motor on the integrated printer was less
than an inch away from the B: drive. Another reason to shield
things.
Most "PC" boxes from the 1970's had some sort of basic design
problem; EMI radition being only one of them (Did the Horizon pass
VDE certification?). Most couldn't withstand a hipot attack; very
few could survive a thermal stress or shake table session without
having a component with "flying leads" dismount, or having cards pop
out of the backplane connectors.
Cheers,
Chuck
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