PERQness...

Jules Richardson julesrichardsonuk at yahoo.co.uk
Tue Jul 3 17:34:01 CDT 2007


Tony Duell wrote:
>>    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....

Yep... I just wondered if the pulleys were deliberately shimmed to allow a bit 
of fine tuning either way or something. It's not really that big a deal - I'd 
just rather a belt that didn't drag at all just to keep wear as low as I can.

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

There's probably a Hoover manual somewhere covering the mechanical side ;)

>>    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. 

True. I don't remember the manual I was looking at for sure - I think it was 
"Guide to PNX" or somesuch, big thing about an inch thick. It mentioned 'bye' 
and 'shutdown' (in tandem with issuing a kill) in the same paragraph but 
wasn't too clear on what exactly did what.

I think I'm just too used to newer UNIX systems that take a few minutes to 
shutdown, so the couple of seconds or so of the PERQ just seemed way too fast :-)

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

Ouch. Yes, I think I've read that somewhere before (probably on here!)

>> (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. 

Yep. I made a fuss about it a while ago when we needed to move our other PERQ 
1 :-)




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