PERQness...

Tony Duell ard at p850ug1.demon.co.uk
Tue Jul 3 15:04:29 CDT 2007


> 
> 
> Spent a fun morning messing around with a PERQ 1, which is the first time I've 
> ever got the chance to actually sit in front of a working example...
> 
> A few questions:
> 
>    1) The hard disk (Shugart SA4008) drive belt seems to have a habit of 
> running 1mm or so out of line at startup, resulting in it rubbing against the 
> chassis beneath the spindle pulley. Once it picks up speed it sorts itself 
> out, but I was wondering whether there's any adjustment in either the spindle 
> pulley or drive motor in order to get it to run a little better?

IIRC those pulleys are 'crowned' -- that is they are convex. The belt 
will run towards the edge when it's running slowly, and will come to the 
middle when it's up to speed. I don't know of anything you can do about 
this. Maybe fiddle with the motor position, but....

The SA4000 service manual that I have has full schematics and PCB layouts 
but nothing on the mechanical side at all.


[...]

>    3) Shutdown procedure - is 'bye' sufficient or do I need to be doing 
> something else first? The manual's a little ambiguous on this (and 'bye' alone 
> executes so unbelievably quickly that it made me worry it wasn't correctly 
> flushing files, parking heads etc.)

I always did sync 3 times before bye. It can't hurt. 

bye will park the heads on a PERQ1 (or 1A), but puts them in totally the 
wrong place on later machines (!).

> 
> (I seriously love that hard disk - it's got a wonderful backyard-engineering 
> made-from-washing-machine-parts feel to it :-)

It is rather fun. I assume you know to lock the positioner and the 
spindle before moving the machine. 

-tony



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