TL Audio VTC - Manual (Page 51)

51
The external monitoring inputs are routed off PC355 by the IDC cable at CN7, to the Control Room
and Studio module, PC352.
4.16. Metering.
The console is fitted as standard with retro-style VU meters for the eight groups plus left and right
outputs. Each of these meters also has a peak LED adjacent to it. Control of the meters and LEDs is
from PC344, located on the master section rear panel and connected to the backplane, PC355, by an
IDC cable.
The circuit diagram for the meter controller is CD1334, which shows the meter trims accessible from
the rear panel, and the peak detect circuits. There is an overall peak threshold trim, also accessible
from the rear panel. The default calibration for the trimmers is 0VU = +4dBu and peak LED
threshold = +18dBu.
4.17. Meter Bridge Option.
The meter controller, PC344, and rear panel of each input section carry a 25 pin “D-type” connector
for connection of the optional LED bargraph meter bridge. The circuit diagrams for the meter bridge
are CD1353 (input sections) and CD1354 (master section). The master section of the bridge includes
“Send” and “Return” switching, which is bussed on 3 pin headers to all input sections, where it
selects between the tape send (Direct Out) or return (Monitor) input.
Power to the meter bridge is also conveyed on the D-type connector. There is a master calibration
trimmer on the rear of each meter bridge PCB, which should be used to set the 0VU point of the
bargraphs in that section, plus an individual bargraph offset trim which should be used to set the “on”
threshold of the lowest LED in the bargraph. The offset trim will need to be re-adjusted if the lowest
LED segment illuminates when there is no signal present. To access the trimmers, the relevant rear
section of the meter bridge needs to be removed - this is possible without removing the entire meter
bridge from the console.