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

[Davis, Jack L. KTXL]

Message: 6
Date: Wed, 26 Oct 2005 21:07:16 -0400
From: Xen Scott <xenscott at earthlink.net>
Subject: [BC] ACR-25 and TCR-100 quad cart machines
To: Broadcast Radio Mailing List <broadcast at radiolists.net>
Message-ID: <5.2.0.9.2.20051026203958.00a1f830 at pop.earthlink.net>
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At 02:51 PM 10/26/05 -0500, Ron Cole wrote:
>We used to make dub reels for all of the newscast stop sets... so when 
>the
>ACR failed we could get out of the stopset intact and hope the engineer
could
>get the ACR running ASAP.
>
>On 10/26/05, Jack Antonio <JAntonio at ktvn.com> wrote:
> >
> > ...my impression of RCA VTRs compared to Ampex, was that the RCAs
> broke >more often, but were easier to fix than the Ampex machines...

I had about 15 years experience with Ampex ACR-25s at KYW-TV in
Philadelphia.
Any machine of this mechanical and electronic complexity will require some
preventive maintenance and will fail from time to time.  Those of you who
never saw or worked with the Ampex ACR-25 can get a sense of the machine by
knowing that the maintenance manual came in a set of 10 notebooks and that
the schematic drawing of the air system was a two page foldout.  The key to
reliable performance was to have the station maintenance techs attend Ampex
training school and then get lots of experience with the machine.

However, the ACR-25 could do things not possible with any other VTR such
as random access, instant start, and playback of any number of carts
with durations anywhere from ten seconds to six minutes, or longer if
you programmed a series of cart plays.  The Ampex ACR-25 was generally
pretty reliable, especially the later versions, as long as it was kept
clean and cool.  Early models were bothered by static electricity and some
design problems which were fixed with field modifications.  Using the same
brand of good quality videotape in all carts improved reliability greatly.
It was also important to replace damaged or stressed videotape so it
wouldn't cause a later problem.

I once made 56 ACR-25 plays (news pieces, graphic backgrounds, bumpers
and other news production) into a one hour local news program, not
including commercials which played from a second ACR-25.  I also
aired a complete one hour program from an ACR-25 which consisted of
a sequence of segments recorded on six-minute cassettes.

I understand that the record for the most number of carts played
in a local break was held by WTTG-TV in Washington.  They aired
22 carts between one local movie segment and the next.

Xen Scott


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 RCA had more
mechanical failures that were fairly easy to fix.  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.  

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.  

I had one machine with a buffer and a second with a TBC.  The buffer was
better at recovery but the TBC was much less complex.  Servo errors would
unlock the time base corrector but the buffer would just keep going.

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.  The idea was to have the loop centered, if it pulled out or
bottomed you were screwed.  The servo would try to correct and it would
actually weld the reel hub to the drive platter.  The drive had a neoprene O
ring glued to it and it would also fuse into the plastic reel hub. At times
you would have to use a big screwdriver to pry the cassette off the drive
hub to get it out of the machine. 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.  We always kept a box of lamps under the deck so you
could replace one quickly, it was the most common failure on the machine.

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.  

Both of them could be a bit dangerous to poke your fingers into, lots of
sudden rapid movement.  Every maintenance engineer that ever worked on a
TCR-100 learned the hard way NOT to shine a flashlight into the back.  It
would trip the tape photocells and cause the reel servo to rip the tape off
the one of the reels.  The "tractor" belt on the TCR-100 was very powerful
and could do some real damage if you got something caught in it!

If you look at the complexity of either machine and remember they were made
in the 70's you would wonder how they worked at all!  They were really
cutting edge at the time and very technologically advanced.  No LSI and no
microprocessors!

Jack Davis
K6YC