27 Jan
2015
27 Jan
'15
2:36 p.m.
Responding on-list to an off-list message, with permission...
On Jan 27, 2015, at 09:30 , Lou Ernst <louis.ernst at verizon.net> wrote:
This is not silly. I think it can work. I had a
similar idea about TU60 decassettes. My task was easier there though since the TU60 uses
standard Philips compact cassette shells. The TU60 however has no capstan and uses the
spindle motors to maintain tape temsion. It was designed by the same guy who designed
dectape (TU55/56).
Using the spindle motors to maintain tape tension seems like a better scheme than that
danged drive belt in my opinion. I recall reading somewhere online about the heroic
measures that some engineers (at HP? Or was it 3M?) had to go to to get a DC-100A-like
cartridge design working, involving lots of hard work in the areas of lubricants, surface
finish, and how to make that drive belt by stretching out a small disc of plastic. My
interpretation is that they had to apply heroic efforts to make a crappy design barely
work. ;)
Long story short, I was able to play TU60
cassettes in a good audio cassette deck and digitize the audio on a PC. I manipulated the
audio file in Audacity. I was able to cut single data blocks and dump the blocks to a long
.CSV file. I opened these in Excel and created intelligence in the spreadsheet to digest
the audio samples back into the block data, even properly decoding the header and checking
the checksum. The hardest work in the spreadsheet was tracking the bit boundaries due to
the temporally varying bit-rate (no capstan in the real TU60).
Cool!
At last I did not have to use this means of
recovering data from TU60 cassettes. My real TU60/TA11 worked well enough to recover the
data on the cassettes I was provided to recover. I developed that tape deck/digitizing
method in case there were dropouts unrecoverable by the real TU60.
At least the real TU60 isn't hobbled by that dreadful cartridge design.
Perhaps you can build a sort of open frame
reel-to-reel deck to play and digitize the tu58 tapes.
That's what I'm thinking. While I could repeatedly use one or two good
cartridge/belt assemblies with the guts of multiple tapes in order to image them in a
TU58-XA transport, I don't relish the thought of repeatedly tinkering with the danged
belt if I can come up with a better solution.
I found a specification that includes the magnetic track dimensions of the DECTAPE II on
Al's site:
http://bitsavers.trailing-edge.com/pdf/dec/dectape/tu58/TU58_Engineering_Sp…
Also, I found a diagram showing track dimensions for various audio cassette formats here:
http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-a…
in particular:
http://www.richardhess.com/tape/cass_trk_lrg.gif
Both the DECTAPE II media and standard audio cassette media are 0.15" (3.81mm) wide.
DECTAPE II has two .057" (1.448mm) wide tracks, centered 0.046" (1.168mm) apart.
Data density is 800 BPI, with 2400 flux reversals per inch. At standard read speed of 30
ips, that turns into bits in 41.7us increments and flux changes in 13.9us increments. The
reels inside the cartridge will spin at around 380 to 800 RPM depending on how much tape
is on them, if I still know how to do math. Or twice that at the scanning speed of 60
ips.
Just based on track geometry, it seems to me that it may be quite possible to read DECTAPE
II media with the inner two tracks of a 4-track recorder head or auto-reversing stereo
audio deck head. Or even with both tracks of a 2-track 2-channel head as shown in the
diagram I found, though I don't know how common those are. 4-track recorders and
auto-reversing stereo decks are pretty common, though.
Running the tape at a stable speed near 30 ips instead of 1-7/8 ips would be the hardest
part, I think. My gut feeling is that a normal audio cassette capstan and pinch roller
assembly may not work well at 16x normal speed, and I haven't seen references to any
audio cassette tape applications that run the tape at controlled speeds that fast (rewind
and fast-forward speeds may be that fast or faster, but those run the tape at unregulated
speeds with the pinch roller disengaged).
I don't know if audio tape heads are electrically suitable for this application, but I
think they might be since the flux change period is in the same ballpark as the AC bias
frequency used in cassette recorders, so the head coils ought to respond ok at those
higher frequencies (?).
I'm curious about what folks with deeper magnetic media experience than I have might
think about this.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
27 Jan
27 Jan
3:58 p.m.
I can't find it at the moment but somewhere I have a Burroughs digital
cassette drive, capstan-less and capable of high-speed bidirectional seek.
AFAIK it uses the standard half-track mono tape format, one track for data
and the other for the clock.
Don't know if it'd be useful and not sure if I want to part with it
permanently, but keep it in mind if nothing else works out and you get
desperate ;-)
mike
----- Original Message -----
From: "Mark J. Blair" <nf6x at nf6x.net>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, January 27, 2015 5:36 PM
Subject: Re: Destructive Imaging of DECTAPE II Media
Responding on-list to an off-list message, with permission...
On Jan 27, 2015, at 09:30 , Lou Ernst <louis.ernst at verizon.net> wrote:
This is not silly. I think it can work. I had a
similar idea about TU60
decassettes. My task was easier there though since the TU60 uses standard
Philips compact cassette shells. The TU60 however has no capstan and uses
the spindle motors to maintain tape temsion. It was designed by the same
guy who designed dectape (TU55/56).
Using the spindle motors to maintain tape tension seems like a better scheme
than that danged drive belt in my opinion. I recall reading somewhere online
about the heroic measures that some engineers (at HP? Or was it 3M?) had to
go to to get a DC-100A-like cartridge design working, involving lots of hard
work in the areas of lubricants, surface finish, and how to make that drive
belt by stretching out a small disc of plastic. My interpretation is that
they had to apply heroic efforts to make a crappy design barely work. ;)
Long story short, I was able to play TU60
cassettes in a good audio
cassette deck and digitize the audio on a PC. I manipulated the audio file
in Audacity. I was able to cut single data blocks and dump the blocks to a
long .CSV file. I opened these in Excel and created intelligence in the
spreadsheet to digest the audio samples back into the block data, even
properly decoding the header and checking the checksum. The hardest work
in the spreadsheet was tracking the bit boundaries due to the temporally
varying bit-rate (no capstan in the real TU60).
Cool!
At last I did not have to use this means of
recovering data from TU60
cassettes. My real TU60/TA11 worked well enough to recover the data on the
cassettes I was provided to recover. I developed that tape deck/digitizing
method in case there were dropouts unrecoverable by the real TU60.
At least the real TU60 isn't hobbled by that dreadful cartridge design.
Perhaps you can build a sort of open frame
reel-to-reel deck to play
and digitize the tu58 tapes.
That's what I'm thinking. While I could repeatedly use one or two good
cartridge/belt assemblies with the guts of multiple tapes in order to image
them in a TU58-XA transport, I don't relish the thought of repeatedly
tinkering with the danged belt if I can come up with a better solution.
I found a specification that includes the magnetic track dimensions of the
DECTAPE II on Al's site:
http://bitsavers.trailing-edge.com/pdf/dec/dectape/tu58/TU58_Engineering_Sp…
Also, I found a diagram showing track dimensions for various audio cassette
formats here:
http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-a…
in particular:
http://www.richardhess.com/tape/cass_trk_lrg.gif
Both the DECTAPE II media and standard audio cassette media are 0.15"
(3.81mm) wide. DECTAPE II has two .057" (1.448mm) wide tracks, centered
0.046" (1.168mm) apart. Data density is 800 BPI, with 2400 flux reversals
per inch. At standard read speed of 30 ips, that turns into bits in 41.7us
increments and flux changes in 13.9us increments. The reels inside the
cartridge will spin at around 380 to 800 RPM depending on how much tape is
on them, if I still know how to do math. Or twice that at the scanning speed
of 60 ips.
Just based on track geometry, it seems to me that it may be quite possible
to read DECTAPE II media with the inner two tracks of a 4-track recorder
head or auto-reversing stereo audio deck head. Or even with both tracks of a
2-track 2-channel head as shown in the diagram I found, though I don't know
how common those are. 4-track recorders and auto-reversing stereo decks are
pretty common, though.
Running the tape at a stable speed near 30 ips instead of 1-7/8 ips would be
the hardest part, I think. My gut feeling is that a normal audio cassette
capstan and pinch roller assembly may not work well at 16x normal speed, and
I haven't seen references to any audio cassette tape applications that run
the tape at controlled speeds that fast (rewind and fast-forward speeds may
be that fast or faster, but those run the tape at unregulated speeds with
the pinch roller disengaged).
I don't know if audio tape heads are electrically suitable for this
application, but I think they might be since the flux change period is in
the same ballpark as the AC bias frequency used in cassette recorders, so
the head coils ought to respond ok at those higher frequencies (?).
I'm curious about what folks with deeper magnetic media experience than I
have might think about this.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
4:32 p.m.
On 2015-Jan-27, at 3:58 PM, Mike Stein wrote:
I can't find it at the moment but somewhere I have
a Burroughs digital cassette drive, capstan-less and capable of high-speed bidirectional
seek. AFAIK it uses the standard half-track mono tape format, one track for data and the
other for the clock.
That description fits the tape system used in the HP9830. The tape transport is actually a
"DigiDeck" OEM'd by International Computer Products, out of Dallas, Texas.
The head is non-standard though, in that it R/Ws both half-tracks simultaneously.
Don't know if it'd be useful and not sure if I
want to part with it permanently, but keep it in mind if nothing else works out and you
get desperate ;-)
I don't think it would be of any benefit to the OP's interest over what he already
has to work with.
6:51 p.m.
----- Original Message -----
From: "Brent Hilpert" <hilpert at cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, January 27, 2015 7:32 PM
Subject: Re: Destructive Imaging of DECTAPE II Media
On 2015-Jan-27, at 3:58 PM, Mike Stein wrote:
I can't find it at the moment but somewhere I have
a Burroughs digital
cassette drive, capstan-less and capable of high-speed bidirectional seek.
AFAIK it uses the standard half-track mono tape format, one track for data
and the other for the clock.
That description fits the tape system used in the HP9830. The tape transport
is actually a "DigiDeck" OEM'd by International Computer Products, out of
Dallas, Texas. The head is non-standard though, in that it R/Ws both
half-tracks simultaneously.
Don't know if it'd be useful and not sure if I
want to part with it
permanently, but keep it in mind if nothing else works out and you get
desperate ;-)
I don't think it would be of any benefit to the OP's interest over what he
already has to work with.=
----- Reply -----
Probably not, but I thought I'd mention it just in case; it doesn't use a
pinch roller though, and it is completely digital, FWIW.
I don't recall whether it was a DigiDeck, but ISTR that I compared the BBM
unit to another digital deck that was (relatively) popular way back when,
and I'm pretty sure that they were different.
http://www.picklesnet.com/burroughs/images/fullsize/burr0050.jpg
They were mostly used with Burroughs Series L machines, but I think some of
the small B series could also be equipped with them. I've still got a few
boxes of utility, game and program tapes for Burroughs L series machine, but
working L's are pretty thin on the ground so I sometimes toy with building
an emulator; that's why I still have the tapes and the drives (although
unfortunately I threw out a lot of paper tapes a long time ago), but that
project is pretty far down on the list...
Just a thought...
m
7:04 p.m.
On 2015-Jan-27, at 6:51 PM, Mike Stein wrote:
----- Original Message ----- From: "Brent Hilpert" <hilpert at
cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk at
classiccmp.org>
Sent: Tuesday, January 27, 2015 7:32 PM
Subject: Re: Destructive Imaging of DECTAPE II Media
On 2015-Jan-27, at 3:58 PM, Mike Stein wrote:
Can't tell from that pic - can't see internals.
Pics of the 9830 transport well down the page here:
http://www.cs.ubc.ca/~hilpert/e/HP9830/gallery/index.html
Some tech details of use in the 9830:
http://www.cs.ubc.ca/~hilpert/e/HP9830/hardware.html#tape
although I should correct my earlier statement: the HP uses 2 half-tracks for 1 bits and 0
bits, not data and clock as you indicate for the Burroughs, but they're still very
similar, the diff would just be in the electronics.
I can't find it at the moment but somewhere I
have a Burroughs digital cassette drive, capstan-less and capable of high-speed
bidirectional seek. AFAIK it uses the standard half-track mono tape format, one track for
data and the other for the clock.
That description fits the tape system used in the HP9830. The tape transport is actually
a "DigiDeck" OEM'd by International Computer Products, out of Dallas,
Texas. The head is non-standard though, in that it R/Ws both half-tracks simultaneously.
Don't know if it'd be useful and not sure
if I want to part with it permanently, but keep it in mind if nothing else works out and
you get desperate ;-)
I don't think it would be of any benefit to the OP's interest over what he
already has to work with.=
----- Reply -----
Probably not, but I thought I'd mention it just in case; it doesn't use a pinch
roller though, and it is completely digital, FWIW.
I don't recall whether it was a DigiDeck, but ISTR that I compared the BBM unit to
another digital deck that was (relatively) popular way back when, and I'm pretty sure
that they were different.
http://www.picklesnet.com/burroughs/images/fullsize/burr0050.jpg
They were mostly used with Burroughs Series L machines, but I think some of the small B
series could also be equipped with them. I've still got a few boxes of utility, game
and program tapes for Burroughs L series machine, but working L's are pretty thin on
the ground so I sometimes toy with building an emulator; that's why I still have the
tapes and the drives (although unfortunately I threw out a lot of paper tapes a long time
ago), but that project is pretty far down on the list...
8:48 p.m.
----- Original Message -----
From: "Brent Hilpert" <hilpert at cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, January 27, 2015 10:04 PM
Subject: Re: Destructive Imaging of DECTAPE II Media
On 2015-Jan-27, at 6:51 PM, Mike Stein wrote:
----- Original Message ----- From: "Brent Hilpert" <hilpert at
cs.ubc.ca>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Tuesday, January 27, 2015 7:32 PM
Subject: Re: Destructive Imaging of DECTAPE II Media
On 2015-Jan-27, at 3:58 PM, Mike Stein wrote:
Can't tell from that pic - can't see internals.
Pics of the 9830 transport well down the page here:
http://www.cs.ubc.ca/~hilpert/e/HP9830/gallery/index.html
Some tech details of use in the 9830:
http://www.cs.ubc.ca/~hilpert/e/HP9830/hardware.html#tape
although I should correct my earlier statement: the HP uses 2 half-tracks
for 1 bits and 0 bits, not data and clock as you indicate for the Burroughs,
but they're still very similar, the diff would just be in the electronics.
----- Reply -----
No, completely different mechanically and electronically, and the analog and
most of the digital electronics are on a set of five cards at the back of
the unit.
But that doesn't mean they couldn't read each other's tapes with some effort
and a few jumper wires ;-)
Found the Tech manuals; FWIW:
Model: A9490
Read speed:
Start & stop: 10 ips
Continuous: 30 ips
Write speed: 10 ips
Mode:
NRZ (2 tracks, clock & data)
or (optional):
PE (Single track, can use both sides)
Rewind speed: 60 ips
Doesn't Al have one of these at the CHM on a B700 or something similar?
I can't find it at the moment but somewhere I
have a Burroughs digital
cassette drive, capstan-less and capable of high-speed bidirectional
seek. AFAIK it uses the standard half-track mono tape format, one track
for data and the other for the clock.
That description fits the tape system used in the HP9830. The tape
transport is actually a "DigiDeck" OEM'd by International Computer
Products, out of Dallas, Texas. The head is non-standard though, in that
it R/Ws both half-tracks simultaneously.
Don't know if it'd be useful and not sure
if I want to part with it
permanently, but keep it in mind if nothing else works out and you get
desperate ;-)
I don't think it would be of any benefit to the OP's interest over what he
already has to work with.=
----- Reply -----
Probably not, but I thought I'd mention it just in case; it doesn't use a
pinch roller though, and it is completely digital, FWIW.
I don't recall whether it was a DigiDeck, but ISTR that I compared the BBM
unit to another digital deck that was (relatively) popular way back when,
and I'm pretty sure that they were different.
http://www.picklesnet.com/burroughs/images/fullsize/burr0050.jpg
They were mostly used with Burroughs Series L machines, but I think some
of the small B series could also be equipped with them. I've still got a
few boxes of utility, game and program tapes for Burroughs L series
machine, but working L's are pretty thin on the ground so I sometimes toy
with building an emulator; that's why I still have the tapes and the
drives (although unfortunately I threw out a lot of paper tapes a long
time ago), but that project is pretty far down on the list...
6:28 p.m.
On Jan 27, 2015, at 15:58 , Mike Stein <mhs.stein
at gmail.com> wrote:
I can't find it at the moment but somewhere I have a Burroughs digital cassette
drive, capstan-less and capable of high-speed bidirectional seek. AFAIK it uses the
standard half-track mono tape format, one track for data and the other for the clock.
Don't know if it'd be useful and not sure if I want to part with it permanently,
but keep it in mind if nothing else works out and you get desperate ;-)
If I had one sitting around, then I might consider using it. But I wouldn't want to
borrow one, especially because I'm much better at starting projects than finishing
them. ;)
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
11:24 p.m.
On 1/27/2015 6:28 PM, Mark J. Blair wrote:
Could you use an instrumentation recorder's cassette transport? Teac
made cassette systems with 7 and 9 tracks. Ebay item 251372482082
I believe is a 7 track assembly. Or look for one of their complete units
MR-30, MR40 etc. Might be a good starting point for building up
a reader. They are variable speed units also, with a wide range of speeds.
Bob
--
Dentopedalogy is the science of opening your mouth and putting your foot in it.
I've been practising it for years.
-Prince Philip
On Jan 27,
2015, at 15:58 , Mike Stein <mhs.stein at gmail.com> wrote:
I can't find it at the moment but somewhere I have a Burroughs digital cassette
drive, capstan-less and capable of high-speed bidirectional seek. AFAIK it uses the
standard half-track mono tape format, one track for data and the other for the clock.
Don't know if it'd be useful and not sure if I want to part with it permanently,
but keep it in mind if nothing else works out and you get desperate ;-)
If I had
one sitting around, then I might consider using it. But I wouldn't want to borrow one,
especially because I'm much better at starting projects than finishing them. ;)
11:52 p.m.
On Jan 27, 2015, at 23:24, Bob Rosenbloom <bobalan
at sbcglobal.net> wrote:
Could you use an instrumentation recorder's cassette transport? Teac made cassette
systems with 7 and 9 tracks. Ebay item 251372482082
I believe is a 7 track assembly. Or look for one of their complete units MR-30, MR40 etc.
Might be a good starting point for building up
a reader. They are variable speed units also, with a wide range of speeds.
Hmm, I don't know. I'm not familiar with those yet, so I'll have to search to
learn more about them (especially, how fast they can run the tape with controlled speed).
The mechanics of the thing look sturdy. Thanks for the suggestion!
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
28 Jan
28 Jan
12:05 a.m.
On Jan 27, 2015, at 23:24, Bob Rosenbloom <bobalan
at sbcglobal.net> wrote:
Could you use an instrumentation recorder's cassette transport? Teac made cassette
systems with 7 and 9 tracks. Ebay item 251372482082
I believe is a 7 track assembly. Or look for one of their complete units MR-30, MR40 etc.
Might be a good starting point for building up
a reader. They are variable speed units also, with a wide range of speeds.
Ok, it looks like the top speed of a complete MR-30 is 38.1 cm/s, or 15 ips. That's
half the speed of a normal TU-58, but maybe it's close enough to get a good signal?
And maybe the mechanism can be driven faster? For $24 shipped, it's worth
experimenting with, and if it works, then that solves most of the mechanical hurdles.
Thanks for the lead!
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
27 Jan
27 Jan
5:22 p.m.
On 2015-Jan-27, at 2:36 PM, Mark J. Blair wrote:
I found a specification that includes the magnetic track dimensions of the DECTAPE II on
Al's site:
http://bitsavers.trailing-edge.com/pdf/dec/dectape/tu58/TU58_Engineering_Sp…
Also, I found a diagram showing track dimensions for various audio cassette formats
here:
http://richardhess.com/notes/formats/magnetic-media/magnetic-tapes/analog-a…
in particular:
http://www.richardhess.com/tape/cass_trk_lrg.gif
Both the DECTAPE II media and standard audio cassette media are 0.15" (3.81mm) wide.
DECTAPE II has two .057" (1.448mm) wide tracks, centered 0.046" (1.168mm) apart.
Something's funny there, the C-to-C distance between two tracks has to be greater than
(with separation gap as shown in the manual) or equal to the track width, that is:
C-to-C = TW/2 + SEPGAP + TW/2
C-to-C >= 2*(TW/2)
but:
.046 < .057
Data density is 800 BPI, with 2400 flux reversals per
inch. At standard read speed of 30 ips, that turns into bits in 41.7us increments and flux
changes in 13.9us increments. The reels inside the cartridge will spin at around 380 to
800 RPM depending on how much tape is on them, if I still know how to do math. Or twice
that at the scanning speed of 60 ips.
Just based on track geometry, it seems to me that it may be quite possible to read
DECTAPE II media with the inner two tracks of a 4-track recorder head or auto-reversing
stereo audio deck head.
Do some auto-reversing stereo decks have 4-transducer heads? The ones I've seen (not
many, so I don't know) mechanically flip a 2-transducer head around 180 degrees.
Or even with both tracks of a 2-track 2-channel head
as shown in the diagram I found, though I don't know how common those are. 4-track
recorders and auto-reversing stereo decks are pretty common, though.
Running the tape at a stable speed near 30 ips instead of 1-7/8 ips would be the hardest
part, I think. My gut feeling is that a normal audio cassette capstan and pinch roller
assembly may not work well at 16x normal speed, and I haven't seen references to any
audio cassette tape applications that run the tape at controlled speeds that fast (rewind
and fast-forward speeds may be that fast or faster, but those run the tape at unregulated
speeds with the pinch roller disengaged).
I don't know if audio tape heads are electrically suitable for this application, but
I think they might be since the flux change period is in the same ballpark as the AC bias
frequency used in cassette recorders, so the head coils ought to respond ok at those
higher frequencies (?).
I'm curious about what folks with deeper magnetic media experience than I have might
think about this.
I think the question would be what are the head-gap widths. It's got to be small
enough to adequately discern the linear-rate-of-change of the flux variation on tape. I
don't think that's necessarily going to correspond to the AC bias F in audio
recording, but yes, it's still in the ballpark of 20KHz hi-fi audio.
6:27 p.m.
On Jan 27, 2015, at 17:22 , Brent Hilpert <hilpert
at cs.ubc.ca> wrote:
On 2015-Jan-27, at 2:36 PM, Mark J. Blair wrote:
>
> I found a specification that includes the magnetic track dimensions of the DECTAPE II
on Al's site:
>
>
http://bitsavers.trailing-edge.com/pdf/dec/dectape/tu58/TU58_Engineering_Sp…
[...]
Both the
DECTAPE II media and standard audio cassette media are 0.15" (3.81mm) wide. DECTAPE
II has two .057" (1.448mm) wide tracks, centered 0.046" (1.168mm) apart.
Something's funny there, the C-to-C distance between two tracks has to be greater
than (with separation gap as shown in the manual) or equal to the track width, that is:
C-to-C = TW/2 + SEPGAP + TW/2
C-to-C >= 2*(TW/2)
but:
.046 < .057 Do some auto-reversing stereo decks have 4-transducer
heads? The ones I've seen (not many, so I don't know) mechanically flip a
2-transducer head around 180 degrees.
I have never seen one that moved the heads. I'm pretty sure that I've seen ones
that simply have four coils/gaps, just like the head in a 4-track audio recorder would
have.
I think the question would be what are the head-gap
widths. It's got to be small enough to adequately discern the linear-rate-of-change of
the flux variation on tape. I don't think that's necessarily going to correspond
to the AC bias F in audio recording, but yes, it's still in the ballpark of 20KHz
hi-fi audio.
I'm also blindly assuming that the coil/gap orientations are the same. Well, I could
always avoid the problem by using a real TU58 head; then I have to guide the tape
externally to the head (perhaps using tape guide spools harvested from a sacrificial tape
cart) instead of using the sheet metal guide notch found on typical audio tape heads, and
I need to get that epoxied-in head out of the transport and provide some means to mount
and adjust it. In contrast, my recollection of audio tape heads that I've seen is that
they're usually screwed in place (not epoxied), and in better drives there's even
an alignment adjustment.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/
3621
days inactive
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days old
11 comments
4 participants
participants (4)
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bobalan＠sbcglobal.net -
hilpert＠cs.ubc.ca -
mhs.stein＠gmail.com -
nf6x＠nf6x.net