22 Nov
2007
22 Nov
'07
2:24 p.m.
Subject: FD400 drive troubleshooting
From: "Richard A. Cini" <rcini at optonline.net>
Date: Wed, 21 Nov 2007 19:54:46 -0500
To: "Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
All:
As you all know from previous posts, I?m having trouble with the drive
system on my IMSAI. While I wait to receive a memory board and some other
stuff from a friend of mine, Herb Johnson gave me some new energy in looking
at the existing iCOM Frugal Floppy system.
This system uses Pertec FD400 drives. One works perfectly, the other one
has consistent CRC errors as evidenced by the CRC light on the drive
cabinet, and BDOS errors reported by CP/M. I ensured that the spindle is
engaging the diskette hub, and I also cleaned the heads using a wet cleaning
diskette.
Get in there and scrub the head with a swab. I found the wet disks didn't
cut it long ago.
Make sure the spindle speed is good and not irregular.
Try swapping drives A and B and se if the problem moves with the drive
or not. Just to make sure you not having a issues with something else.
Is there any common failure mode on this model of drive that I should
start tracking down?
Everyone I'd seen either had fallen apart mechanically (broken hubs,
doors or other plastic) or the drive motor had gone noisy or mechanically
flakey. NOTE: those motors often had bronze (oilite) bearings that dried
out and then became oval or other wise out of useful shape. It was a side
effect of lot of hours and the belts side tension. Result is the motor
speed is uneven. I've seen bad boards too, usually tossed the board and
salvaged from another mechanical pig.
I looked over the maintenance procedures for the
drive
and many if the tests allude to a diagnostics program that can manually
control the spindle and head stepping. None of the iCOM manuals I have
provide diagnostics code for manually controlling the drives in this manner..
There maybe diags but your on you own to find them.
Before I start coding, does anyone have diagnostics
code I can use? I
found some code in the SIGM archive (for the iCOM 3712 controller) but it
doesn?t seem to work properly with this controller.
What controller (CHIP on the FDC board)?
Allison
Thanks.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://highgate.comm.sfu.ca/~rcini/classiccmp
23 Nov
23 Nov
3:50 a.m.
Just a few quick answers:
-- The FD400 is a DC direct drive spindle so no belt. Another list member
gave me a scan of a tach disk to glue on the spindle motor. I will look at
the bearings, etc. I also recall in the past swapping the drives and
concluding it's the drive and not the electronics in the controller.
-- The controller is a two-board totally TTL controller. I have the tech
manual and a BIOS sample so I'm sure I could craft something; I was just
trying to save some time.
Rich
On 11/22/07 9:24 AM, "Allison" <ajp166 at bellatlantic.net> wrote:
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://highgate.comm.sfu.ca/~rcini/classiccmp
Subject: FD400 drive troubleshooting
From: "Richard A. Cini" <rcini at optonline.net>
Date: Wed, 21 Nov 2007 19:54:46 -0500
To: "Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
All:
As you all know from previous posts, I?m having trouble with the drive
system on my IMSAI. While I wait to receive a memory board and some other
stuff from a friend of mine, Herb Johnson gave me some new energy in looking
at the existing iCOM Frugal Floppy system.
This system uses Pertec FD400 drives. One works perfectly, the other one
has consistent CRC errors as evidenced by the CRC light on the drive
cabinet, and BDOS errors reported by CP/M. I ensured that the spindle is
engaging the diskette hub, and I also cleaned the heads using a wet cleaning
diskette.
Get in there and scrub the head with a swab. I found the wet disks didn't
cut it long ago.
Make sure the spindle speed is good and not irregular.
Try swapping drives A and B and se if the problem moves with the drive
or not. Just to make sure you not having a issues with something else.
Is there any common failure mode on this model of drive that I should
start tracking down?
Everyone I'd seen either had fallen apart mechanically (broken hubs,
doors or other plastic) or the drive motor had gone noisy or mechanically
flakey. NOTE: those motors often had bronze (oilite) bearings that dried
out and then became oval or other wise out of useful shape. It was a side
effect of lot of hours and the belts side tension. Result is the motor
speed is uneven. I've seen bad boards too, usually tossed the board and
salvaged from another mechanical pig.
I looked over the maintenance procedures for the
drive
and many if the tests allude to a diagnostics program that can manually
control the spindle and head stepping. None of the iCOM manuals I have
provide diagnostics code for manually controlling the drives in this manner..
There maybe diags but your on you own to find them.
Before I start coding, does anyone have
diagnostics code I can use? I
found some code in the SIGM archive (for the iCOM 3712 controller) but it
doesn?t seem to work properly with this controller.
What controller (CHIP on the FDC board)?
Allison
Thanks.
Rich
--
Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator
http://www.altair32.com
http://highgate.comm.sfu.ca/~rcini/classiccmp
6253
days inactive
6254
days old
1 comments
2 participants
participants (2)
-
ajp166＠bellatlantic.net -
rcini＠optonline.net