16 Jun
2012
16 Jun
'12
7:06 p.m.
I have an old project laying around that I just spent another two hours
on ..
It is an 1993 external parallel port attached CD-ROM. A company called
"Storage Devices Inc" made it, and IBM resold it. The model number is
SCD-683. There are some traces of it if you search the web, but not
much interesting. I have the drivers so that is not a problem.
The CD-ROM is a 1x SCSI unit that uses a caddy. There is a parallel to
SCSI bridge board in the enclosure based on the NCR 53C80 chipset, which
was well known back then. The CD-ROM does show up and talk when used on
an XT running PC DOS 3.3; it responds to commands like eject and it lets
me see its error counts using a utility program.
The problem is that it refuses to read any media that I give it. The
drive is very clean - I removed the top and had a look inside the
mechanism to be certain. It is a caddy loading model so I can't tell for
sure that the head has clear access but everything seems to be operating
freely. I'm using old pressed aluminum discs (OS/2 Warp) which should be
fine in any CD-ROM device. I have tried cleaning the heads with a
special CD that has the magic fibers on it, but nothing is helping. (I
even reached in gently with a Q-tip and isopropyl alcohol, but that did
not change anything.)
I'd like to see this thing run - it has a carry handle on the side!
Unless I come up with another idea to try the only way that is going to
happen is if I swap the drive out. The original drive is an IBM
CDRM00101 and the driver is looking for the ID string. So a drive swap
with a different SCSI drive will probably require patching the device
driver.
So, any ideas on what I can do to clean the head further? (It might just
be hopelessly out of alignment - I don't know the history of the drive.)
Mike
16 Jun
16 Jun
7:31 p.m.
Michael, CD-ROM reading heads isn't so hard to find. Why you don't take
a good photo of the CD optics so we can find something compatible?
---
Enviado do meu Motorola PT550
Meu site: http://www.tabalabs.com.br
----- Original Message -----
From: "Michael B. Brutman" <mbbrutman-cctalk at brutman.com>
To: "CCTalk_list" <cctalk at classiccmp.org>
Sent: Saturday, June 16, 2012 8:06 PM
Subject: Older CD-ROM refuses to read media - ideas for repair?
I have an old project laying around that I just spent
another two hours on
..
It is an 1993 external parallel port attached CD-ROM. A company called
"Storage Devices Inc" made it, and IBM resold it. The model number is
SCD-683. There are some traces of it if you search the web, but not much
interesting. I have the drivers so that is not a problem.
The CD-ROM is a 1x SCSI unit that uses a caddy. There is a parallel to
SCSI bridge board in the enclosure based on the NCR 53C80 chipset, which
was well known back then. The CD-ROM does show up and talk when used on an
XT running PC DOS 3.3; it responds to commands like eject and it lets me
see its error counts using a utility program.
The problem is that it refuses to read any media that I give it. The drive
is very clean - I removed the top and had a look inside the mechanism to
be certain. It is a caddy loading model so I can't tell for sure that the
head has clear access but everything seems to be operating freely. I'm
using old pressed aluminum discs (OS/2 Warp) which should be fine in any
CD-ROM device. I have tried cleaning the heads with a special CD that has
the magic fibers on it, but nothing is helping. (I even reached in gently
with a Q-tip and isopropyl alcohol, but that did not change anything.)
I'd like to see this thing run - it has a carry handle on the side! Unless
I come up with another idea to try the only way that is going to happen is
if I swap the drive out. The original drive is an IBM CDRM00101 and the
driver is looking for the ID string. So a drive swap with a different SCSI
drive will probably require patching the device driver.
So, any ideas on what I can do to clean the head further? (It might just
be hopelessly out of alignment - I don't know the history of the drive.)
Mike
7:49 p.m.
On 6/16/2012 6:31 PM, Alexandre Souza - Listas wrote:
Michael, CD-ROM reading heads isn't so hard to find. Why you don't take
a good photo of the CD optics so we can find something compatible?
I've never heard of that being done - is it really feasible to find a
replacement for a 15+ year old CD-ROM head assembly?
(I'm scared to touch it for fear of knocking it out of alignment, never
mind trying to find a drop in replacement and doing surgery.)
Mike
17 Jun
17 Jun
1:13 a.m.
Michael B. Brutman wrote:
(I'm scared to touch it for fear of knocking it out of alignment,
never mind trying to find a drop in replacement and doing surgery.)
There isn't much in the way of critical alignment. Track following and
focus both use closed-loop servo to the disc.
Anyhow, it's already broken. You're not going to make it worse.
4:40 p.m.
Anyhow, it's already broken. You're not going
to make it worse.
While I would agree that's probably true _in this case_, it could be very
bad advice in other cases.
You might have a unit with a trivial fault, but by messing around with it
in the wrong way, you could turn it into a much worse problem.
For example, you might have a floppy drive with just a drive belt
probklem. But if you mess up the head alignment, you will then not only
have to rpelace the belt but also get an alignment disk... Or you might
haev a machine with an easy-to-get IC that's failed. Mess up the PSU or
zap the thing with static, and yoy may have to also replace many much
harder-to-get ICs
-tony
9:47 a.m.
I've never heard of that being done - is it really
feasible to find a
replacement for a 15+ year old CD-ROM head assembly?
15 years is "new" talking about CD-ROMs. I replace heads sometimes
older...
(I'm scared to touch it for fear of knocking it
out of alignment, never
mind trying to find a drop in replacement and doing surgery.)
It is already broken, isn't it? :o)
9:54 a.m.
Typical failure mechanism for CDROM (and all optical drives) is the
gradual degradation of the LED. If you look closely at the optical head,
you might find a potentiometer that you can tweak to increase the LED
output. Be aware that this will hasten the failure of the LED.
Clint
On Sat, 16 Jun 2012, Michael B. Brutman wrote:
On 6/16/2012 6:31 PM, Alexandre Souza - Listas wrote:
Michael, CD-ROM reading heads isn't so hard to find. Why you don't take
a good photo of the CD optics so we can find something compatible?
I've never heard of that being done - is it really feasible to find a
replacement for a 15+ year old CD-ROM head assembly?
(I'm scared to touch it for fear of knocking it out of alignment, never mind
trying to find a drop in replacement and doing surgery.)
Mike
11:05 a.m.
At 18:06 Uhr -0500 16.6.2012, Michael B. Brutman wrote:
So, any ideas on what I can do to clean the head
further? (It might just
be hopelessly out of alignment - I don't know the history of the drive.)
For a 20 year old CDROM drive, I'd expect the laser diode to fade.
HAND,
hauke
--
"It's never straight up and down" (DEVO)
4:34 p.m.
I have an old project laying around that I just spent another two hours
on ..
It is an 1993 external parallel port attached CD-ROM. A company called
"Storage Devices Inc" made it, and IBM resold it. The model number is
SCD-683. There are some traces of it if you search the web, but not
much interesting. I have the drivers so that is not a problem.
The CD-ROM is a 1x SCSI unit that uses a caddy. There is a parallel to
SCSI bridge board in the enclosure based on the NCR 53C80 chipset, which
was well known back then. The CD-ROM does show up and talk when used on
an XT running PC DOS 3.3; it responds to commands like eject and it lets
me see its error counts using a utility program.
The problem is that it refuses to read any media that I give it. The
drive is very clean - I removed the top and had a look inside the
mechanism to be certain. It is a caddy loading model so I can't tell for
sure that the head has clear access but everything seems to be operating
freely. I'm using old pressed aluminum discs (OS/2 Warp) which should be
fine in any CD-ROM device. I have tried cleaning the heads with a
special CD that has the magic fibers on it, but nothing is helping. (I
even reached in gently with a Q-tip and isopropyl alcohol, but that did
not change anything.)
Most older (at least) CD-ROM drives and CD players do muc hthe same thing
when asked toread a disk. They go through this sequence :
1) Turn on laser, get intensity correct
2) Energize focus coil, move objective lense away from disk until focus
point found (they normally do this a couple of times)
3) Start spindle motor,start to track, get speed correct.
So, you want to see how far into that sequence it's getting. In
particular, is the disk ever spinning when toy try to read it? If not,
it's either that the spidnel motor or its drive is defective _OR_ that
the thin never foudn the focus point, possibly due to problems with the
laser.
If the disk is spinning, there will be a testpoint on the photodiode
preamplifier where you cna conenct a 'scope to see the 'RF Eye' pattern.
Thsi point is often lavelled, amazingly, and conencting a 'scope there is
a good next step.
-tony
4423
days inactive
4424
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8 comments
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participants (6)
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ard＠p850ug1.demon.co.uk -
cctech＠vax-11.org -
eric＠brouhaha.com -
hauke＠Espresso.Rhein-Neckar.DE -
mbbrutman-cctalk＠brutman.com -
pu1bzz.listas＠gmail.com