TU58 yet one more time

Mark J. Blair nf6x at nf6x.net
Tue May 31 10:38:43 CDT 2016

On May 31, 2016, at 00:07, Mattis Lind <mattislind at gmail.com> wrote:
> One thing to think of is that a TU58 drive does not have optical BOT / EOT
> detectors. They make use of special patterns on the tape for this. So to
> format a blank tape can be a tricky operation, possibly manually
> positioning the tape and then just write the nominal number of blocks and
> hope the tape will be long enough.

The TU58-XA mechanism doesn't have the BOT/EOT sensors, but I believe that the tapes still have the BOT/EOT tape perforations and the mirror behind the tape to form a 90 degree optical path. So, it should be possible to add physical BOT/EOT sensors to a TU58-XA mechanism as part of a custom tape imager/formatter project.

The approach I'm hoping to take is different, though, and inspired by my perhaps irrational level of distrust of the tape cartridge design: Transferring the tape to be imaged into an audio cassette housing, and then imaging it on a hacked up transport, thus eliminating that #*&!$*! capstan and belt mechanism from the equation.

I wonder how the TU58 tape's magnetic properties compare to any audio cassette tape formulations? If I could find a way to create new tape belts, then it would be nice to be able to overhaul old cartridges.

On May 31, 2016, at 03:06, Tony Duell <tony_duell at yahoo.co.uk> wrote:

> Now that I have done. I started off with aluminium alloy rpd (I think
> 1/2" diameter, but I can check my notes), turned it down, turned a 
> groove for an o-ring, drilled the centre hole (oddly for a US machine
> this is 3mm, not 1/8" -- and note the motor has different diameter 
> spindles on the 2 ends!) drilled and tapped for the grub screw. With
> a good tape I get a good, stead signal at the right speed at the output
> of the read amplifier.

I like your approach for making a substitute drive wheel.

Mark J. Blair, NF6X <nf6x at nf6x.net>

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