Northstar Horizon Update

From: bluoval <bluoval_at_mindspring.com>
Date: Sat May 22 17:02:27 1999

If you _really_ wanted to check the distance from the leads to the plate, just
put a piece of clay under it and assemble it, then unassemble and look at the
clay.

Anthony Clifton - Wirehead wrote:

> >> > Once those were clipped and a piece of anti-static foam inserted beneath
> >> > the motherboard, the machine now talks to the terminal FAR more reliably
> >> > than before.
>
> >Anti-static foam _is_ slightly conductive, but the resistance would be
> >too high to cause problems with TTL (or LS TTL) signals. Had this been
> >CMOS logic (much higher input impedance, so it's possible to drive the
> >inputs from high impedance sources), I would have been more worried.
> >
> >Although I do wonder why you didn't simply cut off the excess leads
> >yourself...
>
> DOH! =-D Actually, I thought about that. I was going to put some
> plastic underneath but it tends to slide around unless you tape it
> down. I could put tape underneath but that gets icky after a couple
> years. I remembered an Apple II mb a friend had mounted in a PC
> case, which didn't fit the mounting screws, so he used some anti-static
> foam underneath to support it and it worked fine. I've seen it used
> and used it this way all over the place so I guess it never occured to
> me that it could cause a problem.
>
> It certainly hasn't. If anything the machine is more stable now.
> There's just something about a board full of chips with their leads
> an 1/8th inch away from an aluminum ground plane that bothers me.
>
> At any rate, I DID clip the excess leads but since the angles make
> it about impossible to see UNDER the motherboard when it's mounted in
> the chassis, I decided not to take any chances. Plus the back half
> of a N* motherboard is NOT well supported. The center tends to sag
> I bit I notice and I also wanted it supported so I wouldn't get
> intermittants due to cracks in the aging PCB traces.
>
> Note: BTW, I found a reference in the N* newsletters I have to the A2
> 16k ram board being susceptible to noise on the bus. The A3 board,
> which was available also as an upgrade to the A2, has alot better noise
> immunity.
>
> Anthony Clifton
Received on Sat May 22 1999 - 17:02:27 BST