18 Sep
2023
18 Sep
'23
11:05 p.m.
At Mon, 18 Sep 2023 10:55:13 +0200 (CEST) Christian Corti
<cc(a)informatik.uni-stuttgart.de> wrote:
as it will be soon of importance to us, I am seeking
for the systems
engineering manual and drawings, well, everything about the IBM 727 tape
drive (not the 729!). I especially need the module locations charts and
the module schematics.
Just a few weeks ago I donated to the Computer History Museum a set
of 14 original IBM black binders of "Type 7xx" manuals from the
1950s, including the 727. That one is likely to be the same as what's
on bitsavers, but since it's no longer in hand I can't check. They
probably haven't made it through the CHM cataloging process yet.
20 Sep
20 Sep
10:26 a.m.
New subject: IBM 727 tape drive
On Mon, 18 Sep 2023, Len Shustek wrote:
Just a few weeks ago I donated to the Computer History
Museum a set of 14
original IBM black binders of "Type 7xx" manuals from the 1950s, including
the 727. That one is likely to be the same as what's on bitsavers, but since
it's no longer in hand I can't check. They probably haven't made it through
the CHM cataloging process yet.
The background is, we will pick up a 727 drive next week. It appears to be
in a quite decent shape. I would like to restore it as much as possible,
so wiring diagrams, schematics, module utilization charts, in short,
everything that would help, is highly appreciated. The 729 is already
solid state, but the 727 with its tube modules is a real technical beauty :-)
It doesn't seem that there is any other such drive in existence, apart
perhaps at the Museum of Transport and Technology in New Zealand, but they
describe it as "Upright rectangular unit on four wheels" and things like
"A.C. Motor inside unit is coloured metallic blue with red stickers" *lol*
Christian
2:42 p.m.
New subject: IBM 727 tape drive
On Wed, 2023-09-20 at 12:26 +0200, Christian Corti via cctalk wrote:
On Mon, 18 Sep 2023, Len Shustek wrote:
I wonder if Susan Vigor has 727s with her 7094? Probably not.
Just a few weeks ago I donated to the Computer
History Museum a set
of 14
original IBM black binders of "Type 7xx" manuals from the 1950s,
including
the 727. That one is likely to be the same as what's on bitsavers,
but since
it's no longer in hand I can't check. They probably haven't made it
through
the CHM cataloging process yet.
The background is, we will pick up a 727 drive next week. It appears
to be
in a quite decent shape. I would like to restore it as much as
possible,
so wiring diagrams, schematics, module utilization charts, in short,
everything that would help, is highly appreciated. The 729 is already
solid state, but the 727 with its tube modules is a real technical
beauty :-)
It doesn't seem that there is any other such drive in existence,
apart
perhaps at the Museum of Transport and Technology in New Zealand, but
they
describe it as "Upright rectangular unit on four wheels" and things
like
"A.C. Motor inside unit is coloured metallic blue with red stickers"
*lol*
Christian
13 Oct
13 Oct
8:41 a.m.
New subject: IBM 727 tape drive
On Wed, 20 Sep 2023, Van Snyder wrote:
I wonder if Susan Vigor has 727s with her 7094?
Probably not.
That would be 729 drives (the transistorized successor of the 727).
We now have the 727 here (a 727 model III, built in 1957). It is complete
and in a very good shape. It only needs some normal cleaning. The belts,
the bearings and even the "flappers" (vacuum switches) seem to be fine.
Now, the need for 727 manuals has become even bigger :-))
A bit of information can be deduced from reading across the available
727 CE manual, the 753 tape control manual and the 700 series component
circuits manual. But they provide only small pieces that don't form the
whole, especially not the wiring and module charts.
And the interesting part will be to build the DC power supply for the many
voltages (-270V, -130V, -60V, +140V, +270V) and the heater supply.
And building a tape controller...
Christian
1:56 p.m.
New subject: IBM 727 tape drive
On Oct 13, 2023, at 4:41 AM, Christian Corti via
cctalk <cctalk(a)classiccmp.org> wrote:
...
And the interesting part will be to build the DC power supply for the many voltages
(-270V, -130V, -60V, +140V, +270V) and the heater supply.
A good source for information on how to do that would be an older edition of the ARRL
Amateur Radio Handbook. Those can be found, from used book dealers. I have a 1954
edition that would do well, though one from the 1960s is likely also good (perhaps better
since the earlier ones would have vacuum rectifiers, which in a newly built supplly
isn't optimal).
Chances are those voltages don't need to be tightly regulated, not like trying to
build a TWT supply... so the main thing is the transformer(s). Those too can still be
found, or can be built; Hammond (Peter Dahl) is still in that business.
The heater supply is typically just a suitably large 6.3 or 12.6 volt transformer.
paul
2:10 p.m.
New subject: IBM 727 tape drive
On 10/13/2023 8:56 AM CDT Paul Koning via cctalk
<cctalk(a)classiccmp.org> wrote:
Several from the 80s and earlier are available on archive.org:
https://archive.org/search?query=arrl+handbook&and%5B%5D=mediatype%3A%2…
Will
If you want to build a ship, don't drum up people to collect wood and don't assign
them tasks and work, but rather teach them to long for the endless immensity of the sea.
Antoine de Saint-Exupery
On Oct 13, 2023, at 4:41 AM, Christian Corti via
cctalk <cctalk(a)classiccmp.org> wrote:
...
And the interesting part will be to build the DC power supply for the many voltages
(-270V, -130V, -60V, +140V, +270V) and the heater supply.
A good source for
information on how to do that would be an older edition of the ARRL Amateur Radio
Handbook. Those can be found, from used book dealers. I have a 1954 edition that would do
well, though one from the 1960s is likely also good (perhaps better since the earlier ones
would have vacuum rectifiers, which in a newly built supplly isn't optimal).
5:07 p.m.
New subject: IBM 727 tape drive
The valve audio afficionados / suppliers also offer both wisdom and components, e.g.
https://skillbank.co.uk/psu/ and many other sites / blogs
https://www.amazon.co.uk/Designing-Power-Supplies-Amplifiers-Second/dp/0956…
https://shop.elsevier.com/books/valve-amplifiers/jones/978-0-08-096640-3 and many other
titles
https://www.ampmaker.com/shop/vcb-vvr-voltage-control-kit/ and numerous other kits for
worked examples
https://www.thatsaudio.co.uk/product-category/valve-amplifier-transformers-…
Regulation is typically effected by a high voltage N-fet or similar device see e.g.
- https://www.microchip.com/en-us/product/lnd150# etc etc
- https://www.ti.com/lit/pdf/snva020 etc etc
Martin
-----Original Message-----
From: Paul Koning via cctalk [mailto:cctalk@classiccmp.org]
Sent: 13 October 2023 14:57
To: cctalk(a)classiccmp.org
Cc: Paul Koning <paulkoning(a)comcast.net>
Subject: [cctalk] Re: IBM 727 tape drive
On Oct 13, 2023, at 4:41 AM, Christian Corti via
cctalk <cctalk(a)classiccmp.org> wrote:
...
And the interesting part will be to build the DC power supply for the many voltages
(-270V, -130V, -60V, +140V, +270V) and the heater supply.
A good source for information on how to do that would be an older edition of the ARRL
Amateur Radio Handbook. Those can be found, from used book dealers. I have a 1954
edition that would do well, though one from the 1960s is likely also good (perhaps better
since the earlier ones would have vacuum rectifiers, which in a newly built supplly
isn't optimal).
Chances are those voltages don't need to be tightly regulated, not like trying to
build a TWT supply... so the main thing is the transformer(s). Those too can still be
found, or can be built; Hammond (Peter Dahl) is still in that business.
The heater supply is typically just a suitably large 6.3 or 12.6 volt transformer.
paul
5:31 p.m.
New subject: IBM 727 tape drive
On Oct 13, 2023, at 1:07 PM, Martin Bishop
<mjd.bishop(a)emeritus-solutions.com> wrote:
The valve audio afficionados / suppliers also offer both wisdom and components, e.g.
https://skillbank.co.uk/psu/ and many other sites / blogs
https://www.amazon.co.uk/Designing-Power-Supplies-Amplifiers-Second/dp/0956…
https://shop.elsevier.com/books/valve-amplifiers/jones/978-0-08-096640-3 and many other
titles
https://www.ampmaker.com/shop/vcb-vvr-voltage-control-kit/ and numerous other kits for
worked examples
https://www.thatsaudio.co.uk/product-category/valve-amplifier-transformers-…
I wonder if makers of ham radio focused products are likely to be more economical. Tube
audio has some cult aspects to it, and may have pricing to match. (Monster Cable comes to
mind as an analogous case.)
Regulation is typically effected by a high voltage
N-fet or similar device see e.g.
- https://www.microchip.com/en-us/product/lnd150# etc etc
- https://www.ti.com/lit/pdf/snva020 etc etc
Yes, that works if you need regulated power. You can also use tubes to regulate (see the
1967 Handbook on archive.org). That assumes regulation is even needed, which is not often
the case for tube circuits. Also, a simple shunt regulator is often adequate, either a
classic neon tube or a Zener diode (or a couple in series if you need a higher voltage).
I haven't worked with tube computer or logic circuits, but tube circuits in
transmitters or receivers are not normally regulated, with the exception of LC
oscillators. For those, a typical design would just use a neon tube shunt regulator.
paul
5:49 p.m.
New subject: IBM 727 tape drive
The cost of implementing a linear regulator will be modest, measured in £s rather than
10's for the components. Much of the actual cost will be in the pin board layout;
FWIW I have found 3 mm PTFE sheet, drilled as required and fitted with crimp castle posts
works nicely.
One merit of (wide range) linear regulation is that you can ramp up the power rail(s)
during commissioning / fault finding and possibly release less / no magic essence.
Regarding the audiophile magic products I think due diligence is the way forward.
However, fertile ground for 1 April pranks.
Martin
-----Original Message-----
From: Paul Koning [mailto:paulkoning@comcast.net]
Sent: 13 October 2023 18:32
To: Martin Bishop <mjd.bishop(a)emeritus-solutions.com>
Cc: cctalk(a)classiccmp.org
Subject: Re: [cctalk] IBM 727 tape drive
On Oct 13, 2023, at 1:07 PM, Martin Bishop
<mjd.bishop(a)emeritus-solutions.com> wrote:
The valve audio afficionados / suppliers also offer both wisdom and components, e.g.
https://skillbank.co.uk/psu/ and many other sites / blogs
https://www.amazon.co.uk/Designing-Power-Supplies-Amplifiers-Second/dp/0956…
https://shop.elsevier.com/books/valve-amplifiers/jones/978-0-08-096640-3 and many other
titles
https://www.ampmaker.com/shop/vcb-vvr-voltage-control-kit/ and numerous other kits for
worked examples
https://www.thatsaudio.co.uk/product-category/valve-amplifier-transformers-…
I wonder if makers of ham radio focused products are likely to be more economical. Tube
audio has some cult aspects to it, and may have pricing to match. (Monster Cable comes to
mind as an analogous case.)
Regulation is typically effected by a high voltage
N-fet or similar device see e.g.
- https://www.microchip.com/en-us/product/lnd150# etc etc
- https://www.ti.com/lit/pdf/snva020 etc etc
Yes, that works if you need regulated power. You can also use tubes to regulate (see the
1967 Handbook on archive.org). That assumes regulation is even needed, which is not often
the case for tube circuits. Also, a simple shunt regulator is often adequate, either a
classic neon tube or a Zener diode (or a couple in series if you need a higher voltage).
I haven't worked with tube computer or logic circuits, but tube circuits in
transmitters or receivers are not normally regulated, with the exception of LC
oscillators. For those, a typical design would just use a neon tube shunt regulator.
paul
5:45 p.m.
New subject: IBM 727 tape drive
On 10/13/23 10:07, Martin Bishop via cctalk wrote:
Regulation is typically effected by a high voltage
N-fet or similar device see e.g.
- https://www.microchip.com/en-us/product/lnd150# etc etc
- https://www.ti.com/lit/pdf/snva020 etc etc
What, no violet-glow voltage regulator tubes (e.g. VR105)? Horrors!
--Chuck
14 Oct
14 Oct
12:57 a.m.
New subject: IBM 727 tape drive
On 10/13/23 12:07, Martin Bishop via cctalk wrote:
The valve audio afficionados / suppliers also offer
both wisdom and components, e.g.
Ages ago I bought a Potter plug-compatible 9-track tape
drive from a surplus shop. It was designed as a 24xx
compatible drive. I was used to Pertec unformatted drives.
But, apparently, the IBM 2400-series drives had very minimal
logic in them, and fed the analog output from the read amps
directly onto the "bus" cable. Pertec unformatted drives
convert the analog signals through comparators to set FFs
and then produce a trigger pulse that serves as a byte
clock. Making the Potter drive look like a Pertec drive
would be a fair bit of circuitry.
I assume the 727/729 series was similarly primitive, and
would need the same amount of logic to be used.
Jon
404
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10 comments
8 participants
participants (8)
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Christian Corti -
Chuck Guzis -
Jon Elson -
Len Shustek -
Martin Bishop -
Paul Koning -
Van Snyder -
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