Northstar S100 compatability

From: Allison J Parent <allisonp_at_world.std.com>
Date: Fri Mar 20 20:09:47 1998

<Now I'm going to consider voltage wrt the machine ground i.e. the bottom
<of the transformer winding, not the tap.

Also on NS* there is an option to not make the metal chassis DC grond to
the logic. So ground must be the backplane ground.

I suspect Tony has a possible solution, miswiring of the secondary.

<I don't know where you are in the UK (can I conclude from your machine
<name that you are near Peterborough?), but if you think I can be of any
<help, please e-mail me. I have some generic S100 docs (although nothing
<N* specific - if you get anything, I'd be interested in seeing it), and a

I have a full set of NS* docs but I happen to be on the wrong side of the
pond. The PS schematic is pretty trivial. Tony had the design of the
+/- 16v correct.

If you open the power supply up to see the transformer leads 2,3 and 6 are
conneted to ground and common. For the +/-16 leads 5 and 7 go to the
bridge rectifier. For the +8 leads 1 and 4 go to the really big diodes
mounted on the L-shaped bracket.

The 8900uf cap should have -16 to -22v across it and the 11000uf cap +16
to 22v. The largest 180,000uf cap should have +8-10v.

Allison
Received on Fri Mar 20 1998 - 20:09:47 GMT