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Altair 8800c Computer Assembly Hints
Grounding
For maximum resistance to static shock, make sure all sections of the metal cabinet are in electrical con-
tact with each and with the power supply enclosures. Then also ensure the power cord ground wire is
connected to the chassis ground terminal on each of the power supplies.
As shipped, the Altair Clone case has lock washers that bite through the paint where the front panel
bracket attaches to the bottom pan and where the rear panel attaches to the bottom pan. This provides
an electrical connection between these pieces. If you drill holes and use screws to mount the power
supplies, the power supply chassis will most likely have good electrical contact with the bottom case
pan. If not, use lockwashers under the power supply mounting screws.
Unless connected elsewhere, connect the DC terminal used for signal ground to the chassis ground ter-
minal on at least one power supply. This ensures DC ground is at the same potential as chassis ground.
Motherboards with plated mounting holes that are connected to DC ground may make this connection
to chassis ground for you as well.
If putting screws through pre-drilled holes in the cabinet, paint may prevent electrical contact with the
screw. You can slightly ream the holes or use a lockwasher to bite through the paint to ensure electrical
connection to the bottom case pan.
Power Supply Note
An internal lead can accidentally short against a mounting
screw in the small Meanwell RS-15 power supplies as
shown below. Make sure your mounting screws do not
reach in far enough to touch the exposed lead. You can
push the lead a bit to the left with a small screwdriver if
needed.
High Voltage Wiring
The incoming AC hot wire should be routed to an outside
pin on the J2 mating connector. On the opposite outside
position on the J2 mating connector (will be switched AC
hot), run a wire back to the AC line terminal on each power
supply.
Since modern switching power supplies are typically very
well self-protected and contain an internal fuse as a back-
up, an external line fuse is typically not necessary. Howev-
er, if you’re concerned about the AC hot path through the
switch prior to the power supplies, an in-line fuse can be
added there.
