Manual

Issue 3, August 2015 Model 45A User Guide
Page 26 Studio Technologies, Inc.
operating software (“firmware”). Re-pro-
gramming this memory requires using a
specialized programming unit. While not
outrageous in price, it still costs in the
range of US$500. The programmer uses a
ribbon cable and socket to interface with a
6-pin “header” on the Model 45A’s printed
circuit board. And, as you would guess,
once connected reprogramming takes
only a matter of seconds. But unfortunate-
ly the programmer is not something that
would be found in a typical “field shop” or
repair facility.
Two Units can be a TW-12B
Replacement
Two Model 45A units with their 4-wire
interface connectors linked in a crossover
fashion can act as a universal 2-wire-to-
2-wire “bridge.” This should, in theory,
create an updated and improved version
Figure 13. Two Model 45A units connected as a universal 2-wire-to-2-wire bridge
of the venerable Clear-Com TW-12B unit.
In this arrangement two independent
2-wire party-line intercom systems can
function as one while still maintaining full
electrical isolation.
The connection scheme is very simple,
using just four male-female 3-pin XLR
patch cords. The 4-wire outputs of the first
Model 45A would be connected to the
4-wire inputs on the second Model 45A;
the 4-wire outputs on the second Model
45A would connect to the 4-wire inputs
on the first Model 45A. A 2-wire party-line
intercom circuit would connect to each
Model 45A unit. Power can be provided by
the connected intercom circuits or by way
of an external source of 24 volts DC. The
final step to achieve correct performance
is for the auto null function on each Model
45A to be activated. Refer to Figure 13 for
details.