IMI disk drive on Cromemco

[M H Stein]

------------------Original Message
Date: Sat, 31 Mar 2007 21:02:51 -0400
From: info <info at harrells.net>
Subject: IMI disk drive on Cromemco

I have a Cromemco system that came with a IMI model 7700 Hard Drive. The 
drive was working when I got it but was having read errors. I begun 
backup up the files and planned on reformatting. I was able to back up 
the files I need but head a thump like something hit the drive of the 
drive. This is a 10" 5 meg drive with a plastic clear top. The drive 
then began to fail so I power it off and looked around as much as I 
could through the top. I power it back up and now the drive will begun 
ready. The heads look like they never go through the headload process 
but I can't be sure. If I move the unit I can see that the head actuator 
lets the heads float freely in and out.. I have measured all the power 
supply voltages going to the drive and they are good. I don't think it 
was a head crash as I don't see signs on the platters as much as I can 
see through the plastic. The top does look like it can be remove but I 
don't have a clean room I'm holding off until that is the last resort. I 
worked on CDC drives so this looks like one only smaller and without the 
little brush that would sweep the drives before the heads loaded. I 
don't have a manual so I'm limited to what I can do. I have a few 
questions if anyone can help with. The head lock does disengage when 
power is applied.

Does the drive need to come up to speed before voltage is applied to the 
actuator?
Does anyone know where I can find more out on this drive
Should I get ready to make two wall clocks out of the platters?

----------------Reply:
I think Herb Johnson will be able to supply you with a service manual:
http://retrotechnology.com/herbs_stuff/d_crom.html
(7710 IMI 7700 hard disk, 023-6027, January 1982, 100 pp.)

I have one of these drives but it hasn't been powered up for at least 20 
years, so I doubt that it's still good; they weren't too reliable even then.

There was also a 7720 (22MB) version of this drive; they were superseded
by the 5000 (5"FH) IMI drives before Cromemco finally went to ST-506.

I also have the 7000 installation manual, but it only covers connectors, 
switches and schematics for the power supply.

Get ready to make those clocks, but check it out a little more first...

Good luck!

mike