[BC] ACR-25 and TCR-100 quad cart machines

[Xen Scott]

At 01:45 PM 10/27/05 -0500, Jack Davis wrote:
>The ACR-25 was more reliable than the TCR-100 but it took longer to repair
>the Ampex because it was much more complex than the RCA... The ACR-25 was 
>designed by a number of people and had different design for sub assemblies...
>There was TTL, ECL and even some RTL logic depending if you were in the
>servo, buffer or signal sections.

The Ampex ACR-25 was considerably more sophisticated than the TCR-100.
There were considerations given as to which way to rotate the carousel
assembly to get the next cart into to position for loading into a transport
in the shortest amount of time.  The carousel servo also calculated how
much force to apply and that depended upon the number of carts in the carousel
and how the load of carts was distributed.  Having different types of logic
circuitry complicated the spare parts inventory.

>I once took a 60 second spot and put it on 10 ACR carts with 6 seconds on
>each.  If your machine was working properly it would play the spot back with
>no discernable errors.  The ACR could load thread and cue the carts fast
>enough to allow this to happen.  In a really tight situation you could
>inhibit the rewind and it would run even faster.

The rewind inhibit was a plastic twist latch built into each cassette.
It could be set to tell the machine to rewind the cart after playing
or not.  It primarily was used to allow the playing of a six minute
cart followed by a 10 second cart followed by another cart.  There
wasn't enough time to rewind a six minute cart and cue a third cart
while the ten second cart played.  Carts of one minute or less didn't
need to employ rewind lockout.


>The secret was to set up the vacuum columns regularly, we used to do it
>every Friday afternoon to try and keep the calls down on the weekends. The
>tape was buffered in a vacuum column with lamps on one side and photocells
>on the other....  Sometimes the lamps would burn out and when you replaced
>one you had to set it up and the illumination from lamp to lamp was 
>different.

Lamps caused another problem.  At KYW-TV, the filaments could be vibrated
by subway trains passing next to the building.  This caused the servo
system unnecessary stress as it tried to control the position of the
tape in the vacuum column.  The solution to both the variation in
lamp illumination and filament vibration was to replace the incandescent
lamps with infrared LEDs.

>The TCR-100 used pneumatic cylinders for a lot of the process and they made
>a very unique sound when cueing or loading.  The operators could tell if
>there was a problem by the sound of the machine.

The ACR-25 had its signature sounds as well.  A skilled maintenance
tech knew what sounded normal and what sound was associated with a
particular mechanical problem.

Xen Scott