This PCB selects between one of five component video inputs & also provides
the output connector for Zone 3 audio.
IC100, IC101 & IC104 (LT1675CGN video buffers) require +5V & -5V. The
+5V comes direct from L123 & -5V is generated locally from the -15V supply
(from L123).
Selection of the five inputs is via IC102 (74HCT595D serial to parallel
converter, controlled via SPI Clk, Data & Vcomp latch) and IC100, IC101,
IC104. IC102 generates a /ENx signal which tri-states the output when high
and enables the output when low. When low the input is selected with the
SELx signal, high for input1, low for input2.
Truth table:
EN0 SEL0 EN1 SEL1 EN2 SEL2
0 0 1 X 1 x SAT
0 1 1 X 1 x AV
1 x 0 0 1 x VCR
1 x 0 1 1 x DVD
1 x 1 x 0 1 PVR
1 x 1 x 1 x BLANK*
*When component input is not used, BLANK should be selected.
SKT101 provides zone 3 audio output.
L113AY Component Input – Output board