DECTape head problem

[Marc Howard]

8 track tapes use 1/4" wide tape.  Most 8 track units use heads with only
two tracks implemented.  There was a stepper solenoid that moved the head
down (or up after all 4 stereo programs were played).  Growing up in the
60s you never forget things like listening to In-A-Gadda-Da_Vida fade in
the middle of the drum solo and a loud "klunk-klunk" sound and the song
resuming.

Some true 8 track heads were made for mastering pre-recorded tapes and
maybe for consumer recorders.

Marc


On Mon, Feb 7, 2022 at 12:51 PM Michael Thompson via cctech <
cctech at classiccmp.org> wrote:

> DECtapes have 5x redundant tracks. If you could find an 8-track head that
> had the same track pitch, and maybe track width, you could read the tape
> but lose redundancy on the Mark and Timing tracks. That probably would not
> work with a marginal DECtape.
>
> On Mon, Feb 7, 2022 at 3:33 PM Wayne S <wayne.sudol at hotmail.com> wrote:
>
> > I’ve often wondered if the tape heads from consumer tape devices such as
> > cassette or 4-8 track tape players could be used or be made to be used as
> > replacements. Anybody ever try that?
> >
> > Sent from my iPhone
> >
> > > On Feb 7, 2022, at 11:51, Michael Thompson via cctech <
> > cctech at classiccmp.org> wrote:
> > >
> > > 
> > >>
> > >>
> > >> From: Gary Oliver <go at aerodesic.com>
> > >> Subject: DECTape head problem
> > >>
> > >> In debugging my DECtape interface lashup, I found that one of my head
> > >> has two open windings.? Specifically, one channel has an open 'ground'
> > >> with the other two lines apparently the full winding of the channel.?
> > >> The second channel failing has no continuity between any of the three
> > >> lines.? I have tested the other head and it has all the requisite
> > >> continuity so I'm hoping I can at least get a single spindle running.
> > >>
> > >> Has any ever attempted repair of one of these?
> > >>
> > >> -Gary
> > >>
> > >
> > > At the Rhode Island Computer Museum we found several DECtape heads on
> > TU55
> > > and TU56 drives with open connections. A volunteer got one head X-Rayed
> > so
> > > we could see the solder joints between the tiny wires for the head
> coils,
> > > and the larger twinax wires that go to the relay board. We couldn't see
> > any
> > > damage to the wires or solder joints.
> > >
> > > We tried heating the potting material to soften it, and digging it out
> to
> > > get to the solder joints. While digging at the potting material you
> can't
> > > see the tiny wires, so they will likely get damaged.
> > >
> > > We considered using a solvent to remove the potting material, but
> thought
> > > that it would eat the enamel off the head coil wires and damage them
> > beyond
> > > repair.
> > >
> > > So far we haven't found a way to repair the heads.
> > >
> > > Michael Thompson
> >
>
>
> --
> Michael Thompson
>