Looking for RL02 cable and terminator

Tony Duell ard at p850ug1.demon.co.uk
Sun Oct 16 12:29:12 CDT 2005

> Also, I think someone cannibalized the disk brush out of mine :( 
> There is a big open area towards the right rear of the disk
> compartment and a pin with a snapring groove protruding downwards,
> but nothing in the empty hole there except two silver-colored
> tubes down below (air ducts?)... seemed pretty clean inside, as it
> should.

IIRC, the brush assembly was not fitted to later drives (maybe all RL02s 
didn't have it), as it did more harm than good.

Those tubes are air ducts. There are basically 2 airflows in the RLs. The 
first is the cooling air, which comes in at the front through the 
prefilter, through those tubes, which are a sort of heat exchanger to 
cool the disk pack air, and then over the logic and out through the 
muffin fan at the back. The second is the air that recirculates through 
the back and the absolute filter, driven by a fan on the motor. Although 
there is clearly some interchage of air (it's not a sealed-unit 
winchester or anything like that), doing it this way reduces the amount 
of 'dirty' air going onto the abcsolute fiter, so the filter is claimed 
to last longer.

> So I left the heads parked (blocked by the transport plate),
> inserted the disk pack and ran the blower for a while anyway.
> Fault light was on, load light was not. I didn't hook it up to the
> interface board (obviously :) but not being well-acquainted with
> these drives I don't know if it *has* to be connected before the
> fault light goes off, or the heads free to load, or both...

You will get a FAULT light if there's no controller connected. The drive 
needs a clock signal from the controller

> I do have a copy of the "RL01/02 Disk Subsystem User's Manual" but
> the service manual and parts list looks essential at this point.
> Hope it's on bitsavers ;)

The 3 manuals I use a lot are the printset (obviously), a very complete 
technical manual (it even explains the contents of the PROMs on the drive 
logic board) that I've only ever seen on microfiche, and the pocket 
service guide, which has a remarkable amount of useful info in it.


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