IVC TBC

Here is some very heavy weight electronics for its time.

Back in the dark ages of the 1970's a video timebase corrector was a very exotic and expensive
device.

While TRW provided something of a breakthrough with the introduction of their 'Flash' video A
to D converters, one still needed a lot of electronics to make them into a usefull timebase
corrector. IVC's 2001 was one of the first digital timebase correctors to use these new chips, and
the 2002 was a slightly 'improved' version with a larger 32K (!) digital memory.

In contrast to the Ampex TBC6, this IVC was designed to be used with colour-under video tape
recorders, and because of their splitting of the video signal into colour and luminance signals,
they were forced to use 2 TRW chips (at several hundreds of pounds each). Actually it seems
these machines were built for IVC (and designed as well?) by a small company that later became
Quantel.

When you are more used to pushing a pencil (or prodding a keyboard with one finger) for a
living, getting one of these toys working properly is quite an interesting proposition. Here we
see the beast with its top cover removed and the memory board hinged open.

Slightly over a decade ago I acquired a pair of these (after 'having my eye' on them for almost a
decade before), and spent some time putting one good working one together. The manuals were,
as is usual with IVC equipment, very informative and just some board swapping and pot
tweaking did the trick.

The hinged out board has the larger 16 line 32K memory option, the upper centre board is the
broadcast spec. genlock, sync pulse generator and tape clock. To the right of this is the power
supply unit which contains the 4 separate Farnell switched-mode low-voltage power supplies
(behind the cover). Below this are some video band pass filters, the video processing /
enhancement PCB, and to the left of this the output Digital to Analog converters.

The beast still works (great for cleaning up VHS tapes and removing copy protection), though
needs the occasional tickle and tweak.

Here we see the underside of the beast.

The lower left board divides the input video into the chrominace and luminance signals, it then
passes them to the board to its right that slices the signals up 14 million times a second. These 2
streams of signals are passed to the 2 smaller boards above that contain the TRW flash A to D
convertors. The convertors sample these streams of analog data and produce two 8bit data
streams. The data is passed to the 32K memory, where it is clocked out in sync with the time
base corrector's internal oven'ed (high precision) crystal oscillator. The digital data is then
converted back into stable and syncronised composite analog video.

One of the nice things about this particular timebase corrector is that a fair amount of video
processing is also available. And it is an excellent device to tune-up marginal quality video
from the likes of VHS machines.