7 Dec
2021
7 Dec
'21
2:38 p.m.
Hi!
Some time ago, I got my hands on a DECtape II, though no tapes.
That'll change after a long time and in a few days, even multiple
tapes will come in.
With that drive, I started some first tests. It's PSU seems to be
all fine, providing stable 5 and 12 V.
It's board's wire wrapping is in factory settings, so baud rate etc.
is all known.
However, when I checked the two drives capstans, they're old. One
has a crack, and as things go, they feel partially either hard or
gooey. Are there recommendations to exchange these for new ones? I
also noticed that one of the two motors rotates quite freely
(both unconnected from the board, so I'm sure they're not magnetically
braked) while the other ... can be turned without any unreasonable
torque, but it won't continue to spin at all.
Also, when the tapes arrive, are there recommendations in case their
drive belts are gone?
And a final question: There are three firmware versions archived for
the TU58 control board. It's a known version:
jbglaw at charon:~/customers/Glaw/VAX/DECtape II$ md5sum *.bin | sort
0e5f30a960e72c9d64174a4da8f48f50 23-294E2-00.bin
5e059396f779aef9cd80bc75a36c90b2 23-089E2-00.bin
5e059396f779aef9cd80bc75a36c90b2 jbglaw-DECtapeII-ROM.bin
a407fbb5aaa4823a92dd2bc374d1d3ae 23-389E2-00.bin
I guess I got the oldest version? Were there board changes, or could I
put in a compatible 2Kx8 ROM with any of these versions? I guess any
firmware will probably work "good enough", but if I'd avoid known
problems (are the differences known?), I'd rather avoid them.
But after all, I'm quite happy that all the bits'n'pieces will come
together in a few days. Yay!
MfG, JBG
--
7 Dec
7 Dec
7:48 p.m.
On 12/7/2021 4:38 PM, Jan-Benedict Glaw via cctalk wrote:
Hi!
Some time ago, I got my hands on a DECtape II, though no tapes.
That'll change after a long time and in a few days, even multiple
tapes will come in.
With that drive, I started some first tests. It's PSU seems to be
all fine, providing stable 5 and 12 V.
It's board's wire wrapping is in factory settings, so baud rate etc.
is all known.
However, when I checked the two drives capstans, they're old. One
has a crack, and as things go, they feel partially either hard or
gooey. Are there recommendations to exchange these for new ones? I
also noticed that one of the two motors rotates quite freely
(both unconnected from the board, so I'm sure they're not magnetically
braked) while the other ... can be turned without any unreasonable
torque, but it won't continue to spin at all.
I made some up using some two layer rubber hose from Home Depot,
sanded/ground down to the proper diameter.
Also, when the tapes arrive, are there
recommendations in case their
drive belts are gone?
And a final question: There are three firmware versions archived for
the TU58 control board. It's a known version:
jbglaw at charon:~/customers/Glaw/VAX/DECtape II$ md5sum *.bin | sort
0e5f30a960e72c9d64174a4da8f48f50 23-294E2-00.bin
5e059396f779aef9cd80bc75a36c90b2 23-089E2-00.bin
5e059396f779aef9cd80bc75a36c90b2 jbglaw-DECtapeII-ROM.bin
a407fbb5aaa4823a92dd2bc374d1d3ae 23-389E2-00.bin
Interesting. I have no idea which ones I have. Maybe earlier versions
came out for the PDP-11 before the VAXen?
I guess I got the oldest version? Were there board
changes, or could I
put in a compatible 2Kx8 ROM with any of these versions? I guess any
firmware will probably work "good enough", but if I'd avoid known
problems (are the differences known?), I'd rather avoid them.
But after all, I'm quite happy that all the bits'n'pieces will come
together in a few days. Yay!
MfG, JBG
11:43 p.m.
Also, when the tapes arrive, are there recommendations in case their
drive belts are gone?
You can 3D-print replacements.
Use Innoflex filament, 100% fill-in and the following OpenScad formula :
module ring(d1,d2,w)
{
difference()
{ cylinder( w, d1/2, d1/2, $fn=230);
cylinder( w, d2/2, d2/2, $fn=230);
}
}
ring(38.2,35,6); // TU60 Dectape-II
Already 2 TU60 have been repaired with the above.
Jos
8 Dec
8 Dec
1:56 a.m.
On Wed, Dec 8, 2021 at 8:43 AM Jos Dreesen via cctalk
<cctalk at classiccmp.org> wrote:
which Innoflex filament? There are several different hardness variants.
Also, when the tapes arrive, are there recommendations in case their
drive belts are gone?
You can 3D-print replacements.
Use Innoflex filament, 100% fill-in and the following OpenScad formula :
module ring(d1,d2,w)
{
difference()
{ cylinder( w, d1/2, d1/2, $fn=230);
cylinder( w, d2/2, d2/2, $fn=230);
}
}
ring(38.2,35,6); // TU60 Dectape-II
Already 2 TU60 have been repaired with the above.
Useful. Thanks!
--
Regards,
Torfinn Ingolfsen
5:39 p.m.
On Wed, Dec 8, 2021 at 2:43 AM Jos Dreesen via cctalk
<cctalk at classiccmp.org> wrote:
Cool. Thanks for sharing that!
Also, when
the tapes arrive, are there recommendations in case their
drive belts are gone?
You can 3D-print replacements.
Use Innoflex filament, 100% fill-in and the following OpenScad formula :
module ring(d1,d2,w)
{
difference()
{ cylinder( w, d1/2, d1/2, $fn=230);
cylinder( w, d2/2, d2/2, $fn=230);
}
}
ring(38.2,35,6); // TU60 Dectape-II Already 2 TU60 have been repaired with the above.
TU60 are direct-drive digital cassettes.
https://www.pdp-11.nl/peripherals/tape/tu60-info.html
The TU58 uses DC100 cartridges.
http://www.hp9825.com/html/dc100_tape.html
I had a boss who recycled some DEC TU58 for our HP 4951A serial
analyzer. It can format cassettes, the TU58 cannot, so it's a
one-way-trip.
-ethan
7 Dec
7 Dec
11:59 p.m.
On Tue, Dec 7, 2021 at 10:38 PM Jan-Benedict Glaw via cctalk
<cctalk at classiccmp.org> wrote:
However, when I checked the two drives capstans,
they're old. One
has a crack, and as things go, they feel partially either hard or
gooey. Are there recommendations to exchange these for new ones?
I turned a replacement hub from aluminium rod and used an O-ring as
the tyre. It only has to engage with the drive roller in the
cartridge, it doesn't contact the tape of course.
I
also noticed that one of the two motors rotates quite freely
(both unconnected from the board, so I'm sure they're not magnetically
braked) while the other ... can be turned without any unreasonable
torque, but it won't continue to spin at all.
Hmm... Try a drop of light oil on the bearings first.
I'd then try running the motor off a bench supply and measuring the
current it draws. If the 2 motors run properly like that and draw much
the same current then there are no problems.
-tony
876
days inactive
878
days old
6 comments
6 participants
participants (6)
-
ard.p850ug1＠gmail.com -
cube1＠charter.net -
ethan.dicks＠gmail.com -
jbglaw＠lug-owl.de -
jos.dreesen＠greenmail.ch -
tingox＠gmail.com