16 Jan
2023
16 Jan
'23
5:14 a.m.
Hello list,
Yesterday, I was wondering, if there are any multiplatter disk pack production tools known
to exist?
There are disk pack inspection and cleaning tools in the wild (also one on eBay for a
ridiculously high price) and occasionally, I also saw unused and originally packed disk
platters for sale, but these are, to my limited knowledge, worthless if the production and
platter alignment tools are missing.
I remember vaguely somebody writing on this list years ago that some last systems were
tossed by some company in California. But disk packs were also produced on the European
continent and in for instance in Bulgaria(ISOT) for computer disk drives in the federal
republic of Germany and the Soviet Union.
I was just wondering about this since it is getting more and more difficult to come across
disk packs provided that spare unused platters arw available. The (9)877 for the CDC SMD
80MB drives 9762 and OEMs seemed to have been fairly wide-spread and these still show up
from time to time for offer. But the 300MB packs for the CDC 9766 are rare now. Older
drives are close to unobtainium. I never came across a five-platter pack for my CDC 854
drive and i have never seen packs for my MMD 844 or my CDC BC3xx disk drive for 200MB disk
packs.
The question will rise what I wanna do with these. I have a working 9762 drive and some
day, I would like to try to restore the other ones I have. For the SMD drives, I have
spare heads and alignment tools and a disk pack cleaner. I don't intend to run them
for hours because I don't have a clean room environment that is appropriate to the
specs of these drives. I just love these pieces of storage technology and it would be
great to at least have one pack for the drives that are missing one.
Any thoughts from the disk experts would be greatly appreciated :)
Greetings,
Pierre
-----------------------------------------------------------------------------http://www.digitalheritage.de
16 Jan
16 Jan
5:57 a.m.
New subject: Fw: Disk pack production tools
now. Older drives are close to unobtainium. I never
came across a five-platter pack for my CDC 854 drive and i have never seen packs for my
MMD 844 or my CDC BC3xx disk
drive for 200MB disk packs.
Little correction: It's a CDC 844 Multiple Disk Drive, not a 841.
Greetings,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
10:26 a.m.
I bought RK05 packs from Althea (sp?). I know they make diskettes too.
Trying to locate their web site so I must be spelling it wrong :-)
Bill
On Mon, Jan 16, 2023 at 5:14 AM p.gebhardt--- via cctalk <
cctalk(a)classiccmp.org> wrote:
Hello list,
Yesterday, I was wondering, if there are any multiplatter disk pack
production tools known to exist?
There are disk pack inspection and cleaning tools in the wild (also one on
eBay for a ridiculously high price) and occasionally, I also saw unused and
originally packed disk platters for sale, but these are, to my limited
knowledge, worthless if the production and platter alignment tools are
missing.
I remember vaguely somebody writing on this list years ago that some last
systems were tossed by some company in California. But disk packs were also
produced on the European continent and in for instance in Bulgaria(ISOT)
for computer disk drives in the federal republic of Germany and the Soviet
Union.
I was just wondering about this since it is getting more and more
difficult to come across disk packs provided that spare unused platters arw
available. The (9)877 for the CDC SMD 80MB drives 9762 and OEMs seemed to
have been fairly wide-spread and these still show up from time to time for
offer. But the 300MB packs for the CDC 9766 are rare now. Older drives are
close to unobtainium. I never came across a five-platter pack for my CDC
854 drive and i have never seen packs for my MMD 844 or my CDC BC3xx disk
drive for 200MB disk packs.
The question will rise what I wanna do with these. I have a working 9762
drive and some day, I would like to try to restore the other ones I have.
For the SMD drives, I have spare heads and alignment tools and a disk pack
cleaner. I don't intend to run them for hours because I don't have a clean
room environment that is appropriate to the specs of these drives. I just
love these pieces of storage technology and it would be great to at least
have one pack for the drives that are missing one.
Any thoughts from the disk experts would be greatly appreciated :)
Greetings,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
11:30 a.m.
On Mon, 16 Jan 2023, Bill Degnan via cctalk wrote:
I bought RK05 packs from Althea (sp?). I know they
make diskettes too.
Trying to locate their web site so I must be spelling it wrong :-)
I think you're referring to Athana.
g.
--
Proud owner of F-15C 80-0007
http://www.f15sim.com - The only one of its kind.
http://www.diy-cockpits.org/coll - Go Collimated or Go Home.
Some people collect things for a hobby. Geeks collect hobbies.
ScarletDME - The red hot Data Management Environment
A Multi-Value database for the masses, not the classes.
http://scarlet.deltasoft.com - Get it _today_!
17 Jan
17 Jan
3:37 p.m.
Am Montag, 16. Januar 2023 um 17:30:50 MEZ hat geneb via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
Are there still companies like Athana in business that sell new and/or refurbished disk
packs?
I am aware of M.Farris and Associates, but I am not sure, if they are still in active
business. Their compatibility tables for packs and disk drives are fantastic, by the way!
Greetings,
Pierre
I bought RK05
packs from Althea (sp?). I know they make diskettes too.
Trying to locate their web site so I must be spelling it wrong :-)
I think you're referring to Athana. 
16 Jan
16 Jan
11:47 a.m.
On 1/16/23 02:14, p.gebhardt--- via cctalk wrote:
Hello list,
Yesterday, I was wondering, if there are any multiplatter disk pack production tools
known to exist?
There are disk pack inspection and cleaning tools in the wild (also one on eBay for a
ridiculously high price) and occasionally, I also saw unused and originally packed disk
platters for sale, but these are, to my limited knowledge, worthless if the production and
platter alignment tools are missing.
I remember vaguely somebody writing on this list years ago that some last systems were
tossed by some company in California. But disk packs were also produced on the European
continent and in for instance in Bulgaria(ISOT) for computer disk drives in the federal
republic of Germany and the Soviet Union.
I was just wondering about this since it is getting more and more difficult to come
across disk packs provided that spare unused platters arw available. The (9)877 for the
CDC SMD 80MB drives 9762 and OEMs seemed to have been fairly wide-spread and these still
show up from time to time for offer. But the 300MB packs for the CDC 9766 are rare now.
Older drives are close to unobtainium. I never came across a five-platter pack for my CDC
854 drive and i have never seen packs for my MMD 844 or my CDC BC3xx disk drive for 200MB
disk packs.
The question will rise what I wanna do with these. I have a working 9762 drive and some
day, I would like to try to restore the other ones I have. For the SMD drives, I have
spare heads and alignment tools and a disk pack cleaner. I don't intend to run them
for hours because I don't have a clean room environment that is appropriate to the
specs of these drives. I just love these pieces of storage technology and it would be
great to at least have one pack for the drives that are missing one.
Any thoughts from the disk experts would be greatly appreciated :)
The 844 drives date from the early 70s. I worked for CDC on a military
project where these were brought in to replace the 821s that were bid
(yes, I know there's no information on those--they're essentially a
high-capacity unit build on an 808 chassis and unreliable as hell). A
typical installation might have used over 100 of the units on a 4-CPU
Cyber cluster. They worked well, unless one got a bad pack, which would
clobber the heads on a drive; using the drive on a new pack would result
in creating another head-clobbering pack. I recall an overnight report
issued by an operator where he succeeded in trashing several packs and
multiple drives in his attempt to get something to work. It was a
blow-by-blow report somewhat akin to the Gerard Hoffnung bricklayer story.
Can't tell you more about the mechanics of the things--I haven't seen
one of these in many many years. They were the workhorse drive for CDC
large systems for quite some time. We used them on the STAR-100, for
example.
All the best,
Chuck
3:40 p.m.
On Jan 16, 2023, at 11:47 AM, Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
The 844 drives date from the early 70s. ...
Can't tell you more about the mechanics of the things--I haven't seen
one of these in many many years. They were the workhorse drive for CDC
large systems for quite some time. We used them on the STAR-100, for
example.
On the CERL PLATO system at U of Illinois, around 1977, we had 20-ish 844-21 drives, and
maybe a few 844-41 as well. Those were roughly the same as the DEC RP04 and RP05 drives,
same pack and track count. Different sectors, though; 322 12-bit words per sector.
Those are 3600 rpm drives, linear voice coil head actuator, dedicated servo surface. The
details of the format was handled in a sort of microcoded bit handling engine, one of two
engines in the programmable controller (7054). I actually have the source code still
around, and the manual for that beast also still exists.
My favorite for wild mechanics is the IBM 1311 we had on an IBM 1629 Mod II. Those have
hydraulic actuators, 100 cylinders. In the controller, the subtractor that would tell the
machinery how many cylinders there are between the current one and the requested one was
an optional feature ("direct seek option") which we didn't have. Without
the option, all seeks would be done by retracting all the way to cylinder zero, then back
out again the number of cylinders corresponding to what the program asked for. You could
really make the drive shake by feeding it a simple program that stepped through the
cylinders; near the end of the loop it would spend a significant fraction of a second
getting from, say, track 98 to 99.
paul
7:20 p.m.
On 1/16/23 12:40, Paul Koning wrote:
On the CERL PLATO system at U of Illinois, around
1977, we had 20-ish
844-21 drives, and maybe a few 844-41 as well. Those were roughly the
same as the DEC RP04 and RP05 drives, same pack and track count.
Different sectors, though; 322 12-bit words per sector. Those are 3600
rpm drives, linear voice coil head actuator, dedicated servo surface.
The details of the format was handled in a sort of microcoded bit
handling engine, one of two engines in the programmable controller
(7054). I actually have the source code still around, and the manual
for that beast also still exists.
Most of our customers from that time had all of the drive farm as
well as the unit record equipment on MACs. (Predates Apple--Multiple
Access Controller). We kept Spence Preston busy... :
We had a 1311 on a CADET. Slow, but better than the alternatives (cards
or paper tape). Monitor IID, IIRC. Work cylinders were 0-25, IIRC.
No real file system, just DIM entries. I don't recall what options had
to be installed on a CADET to run Monitor, but I think indirect
addressing was a requirement.
My favorite was the CDC 6603/Bryant 4000. That bugger was engineered to
leak oil--it even had plastic jugs inside to collect the drippings. My
fondest memory was watching a COMSOURCE operator run to refill a 501
printer, hitting the Bryant oil patch and falling flat on his back...
--Chuck
17 Jan
17 Jan
3:54 p.m.
Am Dienstag, 17. Januar 2023 um 01:20:22 MEZ hat Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
On 1/16/23 12:40, Paul Koning wrote:
On the CERL PLATO system at U of Illinois, around
1977, we had 20-ish
844-21 drives, and maybe a few 844-41 as well. Those were roughly the
same as the DEC RP04 and RP05 drives, same pack and track count.
Different sectors, though; 322 12-bit words per sector. Those are 3600
rpm drives, linear voice coil head actuator, dedicated servo surface.
The details of the format was handled in a sort of microcoded bit
handling engine, one of two engines in the programmable controller
(7054). I actually have the source code still around, and the manual
for that beast also still exists.
Most of our customers from that time had all
of the drive farm as
well as the unit record equipment on MACs. (Predates Apple--Multiple
Access Controller). We kept Spence Preston busy... :
We had a 1311 on a CADET. Slow, but better than the alternatives (cards
or paper tape). Monitor IID, IIRC. Work cylinders were 0-25, IIRC.
No real file system, just DIM entries. I don't recall what options had
to be installed on a CADET to run Monitor, but I think indirect
addressing was a requirement.
My favorite was the CDC 6603/Bryant 4000. That bugger was engineered to
leak oil--it even had plastic jugs inside to collect the drippings. My
fondest memory was watching a COMSOURCE operator run to refill a 501
printer, hitting the Bryant oil patch and falling flat on his back...
Paul, Chuck, the hydraulic actuator-driven disk systems surely bring maintenance
and related issues to another level and stories :) Thanks!
From what I see at least by the return on our list, there don't seem to be, for
example,
servo writer and disk plattern mechanical alignment tools still around - at least to the
knowledge of the cctalk list members.
I wonder, if the CHM could have any additional knowledge about this and I will contact
Al Kossow out of curiosity regarding this.
Anybody aroundhere who used drives in the last 10 years to read multi-platter disk
packs successfully?
At least the CHM did so to read single-platter disks and archive software (thanks to the
great
videos, curious Marc!), but I don't know if they tried to work with multi-platter
disks.
I recall that the Jim Austin Computer Museum tried to get a 9766 300MB disk drive up and
running, but it suffered a head-crash after a few hours and they decided not to go any
further
down this road...
Greetings,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
3:45 p.m.
Am Montag, 16. Januar 2023 um 17:57:46 MEZ hat Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
Hi Chuck,
The 844 drives date from the early 70s. I worked for
CDC on a military
project where these were brought in to replace the 821s that were bid
(yes, I know there's no information on those--they're essentially a
high-capacity unit build on an 808 chassis and unreliable as hell). A
typical installation might have used over 100 of the units on a 4-CPU
Cyber cluster. They worked well, unless one got a bad pack, which would
clobber the heads on a drive; using the drive on a new pack would result
in creating another head-clobbering pack. I recall an overnight report
issued by an operator where he succeeded in trashing several packs and
multiple drives in his attempt to get something to work. It was a
blow-by-blow report somewhat akin to the Gerard Hoffnung bricklayer story.
Wow, thanks for sharing this story!
Did the 844 drives have the same hydraulic-actuator approach like the MMD 841 drives?
Greetings,
Pierre
-----------------------------------------------------------------------------
http://www.digitalheritage.de
4:58 p.m.
On Jan 17, 2023, at 3:45 PM, P Gebhardt via cctalk
<cctalk(a)classiccmp.org> wrote:
Am Montag, 16. Januar 2023 um 17:57:46 MEZ hat Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
Hi Chuck,
No, 844 drives use linear voice coils (linear motors), which seems to have become the norm
in the early 1970s. RK05 is another example. The term "voice coil" is used
because they look like oversized versions of the coil that drives the speaker cone in
loudspeakers. These all are some sort of servo device; in many of them the servo signal
is on the media, but not always. For example, the RK05 uses a pattern of lines on a glass
substrate attached to the actuator; the "fault" light on the drive indicates a
failure of the light bulb that illuminates the servo pattern.
A common feature of linear motor actuators is an emergency retract circuit, powered by
rather large capacitors, to pull the heads off the disk if there is a power failure.
paul
The 844 drives date from the early 70s. I worked
for CDC on a military
project where these were brought in to replace the 821s that were bid
(yes, I know there's no information on those--they're essentially a
high-capacity unit build on an 808 chassis and unreliable as hell). A
typical installation might have used over 100 of the units on a 4-CPU
Cyber cluster. They worked well, unless one got a bad pack, which would
clobber the heads on a drive; using the drive on a new pack would result
in creating another head-clobbering pack. I recall an overnight report
issued by an operator where he succeeded in trashing several packs and
multiple drives in his attempt to get something to work. It was a
blow-by-blow report somewhat akin to the Gerard Hoffnung bricklayer story.
Wow, thanks for sharing this story!
Did the 844 drives have the same hydraulic-actuator approach like the MMD 841 drives?
5:09 p.m.
On 1/17/23 13:58, Paul Koning via cctalk wrote:
No, 844 drives use linear voice coils (linear motors), which seems to have become the
norm in the early 1970s. RK05 is another example. The term "voice coil" is
used because they look like oversized versions of the coil that drives the speaker cone in
loudspeakers. These all are some sort of servo device; in many of them the servo signal
is on the media, but not always. For example, the RK05 uses a pattern of lines on a glass
substrate attached to the actuator; the "fault" light on the drive indicates a
failure of the light bulb that illuminates the servo pattern.
A common feature of linear motor actuators is an emergency retract circuit, powered by
rather large capacitors, to pull the heads off the disk if there is a power failure.
And, IIRC, a bit red warning sticker on the actuator.
--Chuck
5:14 p.m.
On Jan 17, 2023, at 5:09 PM, Chuck Guzis via cctalk
<cctalk(a)classiccmp.org> wrote:
On 1/17/23 13:58, Paul Koning via cctalk wrote:
Yes indeed. Triggering the emergency retract with the drive open for service could easily
take off fingers. The amount of power involved in moving those head stacks around is
pretty substantial.
paul
No, 844 drives use linear voice coils (linear motors), which seems to have become the
norm in the early 1970s. RK05 is another example. The term "voice coil" is
used because they look like oversized versions of the coil that drives the speaker cone in
loudspeakers. These all are some sort of servo device; in many of them the servo signal
is on the media, but not always. For example, the RK05 uses a pattern of lines on a glass
substrate attached to the actuator; the "fault" light on the drive indicates a
failure of the light bulb that illuminates the servo pattern.
A common feature of linear motor actuators is an emergency retract circuit, powered by
rather large capacitors, to pull the heads off the disk if there is a power failure.
And, IIRC, a bit red warning sticker on the actuator.
--Chuck 
10:18 p.m.
Does anyone know if that light bulb is still available? I’m not sure what
the response of that photo sensor is and that might rule out using a led
replacement. The fact that the bulb is almost certainty driven below the
rated voltage also complicates matters.
Marc
On Tue, Jan 17, 2023 at 5:10 PM Chuck Guzis via cctalk <
cctalk(a)classiccmp.org> wrote:
On 1/17/23 13:58, Paul Koning via cctalk wrote:
And, IIRC, a bit red warning sticker on the actuator.
--Chuck
No, 844 drives use linear voice coils (linear motors), which seems to
have become the norm in the early 1970s. RK05 is another example. The
term "voice coil" is used because they look like oversized versions of the
coil that drives the speaker cone in loudspeakers. These all are some sort
of servo device; in many of them the servo signal is on the media, but not
always. For example, the RK05 uses a pattern of lines on a glass substrate
attached to the actuator; the "fault" light on the drive indicates a
failure of the light bulb that illuminates the servo pattern.
A common feature of linear motor actuators is an emergency retract
circuit, powered by rather large capacitors, to pull the heads off the disk
if there is a power failure.
18 Jan
18 Jan
1:42 p.m.
On 1/17/23 21:18, Marc Howard via cctalk wrote:
Does anyone know if that light bulb is still
available? I’m not sure what
the response of that photo sensor is and that might rule out using a led
replacement. The fact that the bulb is almost certainty driven below the
rated voltage also complicates matters.
If you need JUST ONE badly enough, you can probably keep it
going. Likely an LED could be used as a substitute. But, a
roughly equivalent bulb with the wrong base could likely be
found and hacked.
Jon
19 Jan
19 Jan
2:46 p.m.
On Wed, Jan 18, 2023 at 12:42:26PM -0600, Jon Elson wrote:
On 1/17/23 21:18, Marc Howard via cctalk wrote:
Originally discussing RK05 head position sensor bulb. I have replaced it. The
offical part to replace it isn't available. You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of the
small ones with wires. It doesn't use bulb with base. LED didn't work. I
think sensor is IR.
Does anyone know if that light bulb is still
available? I’m not sure what
the response of that photo sensor is and that might rule out using a led
replacement. The fact that the bulb is almost certainty driven below the
rated voltage also complicates matters.
If you need JUST ONE badly enough, you can probably keep it going. Likely
an LED could be used as a substitute. But, a roughly equivalent bulb with
the wrong base could likely be found and hacked.
4:01 p.m.
On Jan 19, 2023, at 2:46 PM, David Gesswein via cctalk
<cctalk(a)classiccmp.org> wrote:
On Wed, Jan 18, 2023 at 12:42:26PM -0600, Jon Elson wrote:
Hard to know what the sensor wants given that it isn't described in any DEC documents
I could find. The schematics do mention that the light bulb runs on +5 volts, which
suggests that indeed it might be below its rated voltage.
If the sensors want IR you could try an IR LED. Or a white LED on the theory that
it's a broadband light source...
paul
On 1/17/23 21:18, Marc Howard via cctalk wrote:
Originally discussing RK05 head position sensor bulb. I have replaced it. The
offical part to replace it isn't available. You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of the
small ones with wires. It doesn't use bulb with base. LED didn't work. I
think sensor is IR. Does anyone know if that light bulb is still
available? I’m not sure what
the response of that photo sensor is and that might rule out using a led
replacement. The fact that the bulb is almost certainty driven below the
rated voltage also complicates matters.
If you need JUST ONE badly enough, you can probably keep it going. Likely
an LED could be used as a substitute. But, a roughly equivalent bulb with
the wrong base could likely be found and hacked.
10:54 p.m.
Most white LEDs are really blue LEDs with a thin yellow phosphor coating
(the eye sees yellow as red + green). I doubt they have much energy in the
IR range.
IR LED is probably the way to go. How hard is it to get to that bulb?
Marc
On Thu, Jan 19, 2023 at 4:02 PM Paul Koning via cctalk <
cctalk(a)classiccmp.org> wrote:
it. The
On Jan 19, 2023, at 2:46 PM, David Gesswein via
cctalk <
cctalk(a)classiccmp.org> wrote:
On Wed, Jan 18, 2023 at 12:42:26PM -0600, Jon Elson wrote:
> On 1/17/23 21:18, Marc Howard via cctalk wrote:
>> Does anyone know if that light bulb is still available? I’m not sure
what
>> the response of that photo sensor is and
that might rule out using a
led
>> replacement. The fact that the bulb is
almost certainty driven below
the
>> rated voltage also complicates matters.
>
> If you need JUST ONE badly enough, you can probably keep it going.
Likely
> an LED could be used as a substitute. But, a
roughly equivalent bulb
with
the wrong
base could likely be found and hacked.
Originally discussing RK05 head position sensor bulb. I have replaced
offical part to replace it isn't available.
You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of
the
small ones with wires. It doesn't use bulb
with base. LED didn't work. I
think sensor is IR.
Hard to know what the sensor wants given that it isn't described in any
DEC documents I could find. The schematics do mention that the light bulb
runs on +5 volts, which suggests that indeed it might be below its rated
voltage.
If the sensors want IR you could try an IR LED. Or a white LED on the
theory that it's a broadband light source...
paul
20 Jan
20 Jan
12:33 p.m.
I used to gouge out and replace those bulbs in the RK05. The original
part was all in one piece, emitter and receiver, but later they made the
emitter part easy to remove and I kept one re-lamped in my kit for a
quick change.
I still had a pack of them a year or two ago, but donated them to the
National Museum of Computing at Bletchley Park in England. If Sean is
on this list maybe he can read the part number off the package.
cheers,
Nigel
Nigel Johnson, MSc., MIEEE, MCSE VE3ID/G4AJQ/VA3MCU
Amateur Radio, the origin of the open-source concept!
Skype: TILBURY2591
On 2023-01-19 22:54, Marc Howard via cctalk wrote:
> Most white LEDs are really blue LEDs with a thin yellow phosphor coating
> (the eye sees yellow as red + green). I doubt they have much energy in the
> IR range.
>
> IR LED is probably the way to go. How hard is it to get to that bulb?
>
> Marc
>
> On Thu, Jan 19, 2023 at 4:02 PM Paul Koning via cctalk <
> cctalk(a)classiccmp.org> wrote:
>
>>> On Jan 19, 2023, at 2:46 PM, David Gesswein via cctalk <
>> cctalk(a)classiccmp.org> wrote:
>>> On Wed, Jan 18, 2023 at 12:42:26PM -0600, Jon Elson wrote:
>>>> On 1/17/23 21:18, Marc Howard via cctalk wrote:
>>>>> Does anyone know if that light bulb is still available? I’m not
sure
>> what
>>>>> the response of that photo sensor is and that might rule out using
a
>> led
>>>>> replacement. The fact that the bulb is almost certainty driven
below
>> the
>>>>> rated voltage also complicates matters.
>>>> If you need JUST ONE badly enough, you can probably keep it going.
>> Likely
>>>> an LED could be used as a substitute. But, a roughly equivalent bulb
>> with
>>>> the wrong base could likely be found and hacked.
>>>>
>>> Originally discussing RK05 head position sensor bulb. I have replaced
>> it. The
>>> offical part to replace it isn't available. You can open it up and put
in
>>> a new bulb. I wasn't able to quickly find what bulb I used a number of
>>> years ago but if someone really needs to know I can dig further. One of
>> the
>>> small ones with wires. It doesn't use bulb with base. LED didn't
work. I
>>> think sensor is IR.
>> Hard to know what the sensor wants given that it isn't described in any
>> DEC documents I could find. The schematics do mention that the light bulb
>> runs on +5 volts, which suggests that indeed it might be below its rated
>> voltage.
>>
>> If the sensors want IR you could try an IR LED. Or a white LED on the
>> theory that it's a broadband light source...
>>
>> paul
>>
>>
4:27 a.m.
On Thu, 19 Jan 2023, David Gesswein wrote:
Originally discussing RK05 head position sensor bulb.
I have replaced it. The
offical part to replace it isn't available. You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of the
small ones with wires. It doesn't use bulb with base. LED didn't work. I
think sensor is IR.
I have also replaced it many years ago. I bought a hand full of 5V micro
miniature light bulbs with wires. I think I bought them at Bürklin back
then. Anyways, they were a 1:1 match and the replacement works like a
charm. I guess that the filament orientation in the buld is important and
that it should be parallel to the graticule.
Christian
9:43 a.m.
On Jan 20, 2023, at 4:27 AM, Christian Corti via
cctalk <cctalk(a)classiccmp.org> wrote:
On Thu, 19 Jan 2023, David Gesswein wrote:
From the looks of the setup (a Moiré system) you'd want reasonably uniform
illumination. So parallel to the graticule would spread out the light a bit.
paul
Originally discussing RK05 head position sensor
bulb. I have replaced it. The
offical part to replace it isn't available. You can open it up and put in
a new bulb. I wasn't able to quickly find what bulb I used a number of
years ago but if someone really needs to know I can dig further. One of the
small ones with wires. It doesn't use bulb with base. LED didn't work. I
think sensor is IR.
I have also replaced it many years ago. I bought a hand full of 5V micro miniature light
bulbs with wires. I think I bought them at Bürklin back then. Anyways, they were a 1:1
match and the replacement works like a charm. I guess that the filament orientation in the
buld is important and that it should be parallel to the graticule.
16 Jan
16 Jan
11:54 a.m.
On 1/16/23 04:14, p.gebhardt--- via cctalk wrote:
Hello list,
Yesterday, I was wondering, if there are any multiplatter disk pack production tools
known to exist?
There are disk pack inspection and cleaning tools in the wild (also one on eBay for a
ridiculously high price) and occasionally, I also saw unused and originally packed disk
platters for sale, but these are, to my limited knowledge, worthless if the production and
platter alignment tools are missing.
Washington University had a magnetic media lab at one time,
and got several semi loads of gear from an IBM lab. There
were air bearing spindle tables and many racks of IBM
circuitry based on MST chip technology. I assume some of
this could have been used as servo track writers. Any
system that doesn't have a dedicated servo surface or
embedded servo info doesn't need a servo track writer, it
can just format the pack by itself (with proper diagnostic
programs, of course.)
Aligning the heads on the drive is an issue only if you want
to interchange platters. Then, you need an alignment pack -
wow, those would be quite hard to find today! There are
tools like alignment meters that can make the job easier,
but really all you need is a scope and generally a rod with
an eccentric tip to adjust the head position.
Jon
3:32 p.m.
On Jan 16, 2023, at 11:54 AM, Jon Elson via cctalk
<cctalk(a)classiccmp.org> wrote:
On 1/16/23 04:14, p.gebhardt--- via cctalk wrote:
There are a few other odd cases. Fixed head drives might have a timing track; the DEC
RS64 and RF11 do. For those, if you replace the platter you have to rewrite the timing
track, which requires a specialized device. I've seen it done on an RF11 that was
pretty much rebuilt from the base plate upward. The special tools needed -- alignment
disk and timing writer -- had to be sent over from Maynard, they were not standard field
service equipment. The documentation was pretty minimal, but our FS tech was really good
and had no trouble figuring it out. I think it was the first time he did one of these
jobs.
paul
Hello list,
Yesterday, I was wondering, if there are any multiplatter disk pack production tools
known to exist?
There are disk pack inspection and cleaning tools in the wild (also one on eBay for a
ridiculously high price) and occasionally, I also saw unused and originally packed disk
platters for sale, but these are, to my limited knowledge, worthless if the production and
platter alignment tools are missing.
Washington University had a magnetic media lab at one time, and got several semi loads of
gear from an IBM lab. There were air bearing spindle tables and many racks of IBM
circuitry based on MST chip technology. I assume some of this could have been used as
servo track writers. Any system that doesn't have a dedicated servo surface or
embedded servo info doesn't need a servo track writer, it can just format the pack by
itself (with proper diagnostic programs, of course.)
17 Jan
17 Jan
3:41 p.m.
Am Montag, 16. Januar 2023 um 17:55:22 MEZ hat Jon Elson via cctalk
<cctalk(a)classiccmp.org> Folgendes geschrieben:
Washington University had a magnetic media lab at one
time,
and got several semi loads of gear from an IBM lab. There
were air bearing spindle tables and many racks of IBM
circuitry based on MST chip technology. I assume some of
this could have been used as servo track writers. Any
system that doesn't have a dedicated servo surface or
embedded servo info doesn't need a servo track writer, it
can just format the pack by itself (with proper diagnostic
programs, of course.)
Aligning the heads on the drive is an issue only if you want
to interchange platters. Then, you need an alignment pack -
wow, those would be quite hard to find today! There are
tools like alignment meters that can make the job easier,
but really all you need is a scope and generally a rod with
an eccentric tip to adjust the head position.
Jon
Thanks for sharing this information with us, Jon! I wasn't aware that academia got
equipment from industry for research on magnetic media, but it actually makes sense, as a
lot of research was conducted in this field.
I can confirm that finding alignment packs is extremely difficult!
Greetings,
Pierre
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23 comments
11 participants
participants (11)
-
Bill Degnan -
Christian Corti -
Chuck Guzis -
David Gesswein -
geneb -
Jon Elson -
Marc Howard -
Nigel Johnson Ham -
P Gebhardt -
p.gebhardt＠ymail.com
-
Paul Koning