20 Apr
2006
20 Apr
'06
7:48 p.m.
----- Original Message -----
From: "Jay West" <jwest at classiccmp.org>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Wednesday, April 19, 2006 12:33 PM
Subject: Re: HP 1000 cmoputer (parts maybe)
<snip>
Joe is correct here.
Unless the metal plate is installed over the memory boards and controller
two problems will pop up.
First off, airflow over one corner of the memory controller board will be
shunted forward, away from the backplane, and flow behind the front
panel. The 2102B will get flakey under these conditions, depending on
how the memory timing is adjusted (by the pot on the controller board).
Just measure the temperature of the 2102B with and without the metal
plate installed. Measure the far side from the power supply, near the
memory backplane.
I've 'fixed' flakey machines be installing this baffle when it had been
missing.
Of course the correct fix is to replace/repair the 2102B.
Secondly, the memory ribbon cables will act up far more than they do
when this foam-lined metal plate is installed as the factory designed it to
be.
Under the
front panel is a
removeable plate that covers the CPU and memory cards. BTW I've been told
not to run the 1000 sithout the plate since it controls the cooling air
flow.
I suspect the cooling duct is misguided. With the door closed, there's
little difference in airflow. But there's a much better reason to keep
this panel in place. This panel is specifically designed to press tightly
on the ribbon cables that jumper between the memory controller and the
memory cards in the front card cage. This cable is notoriously finnicky.
That is the main reason for this front panel.