SERVICE MANUAL FOR M35&36; CHASSIS

TCL
Output (Fig. 16)
These pins are the analog Red/Green/Blue outputs
of the back-end. The outputs are current sinks.
Pin 45, VSUPAB* . Supply Voltage, Analog Back-end
This pin has to be connected to the analog supply voltage.
No supply current for the digital stages should
flow through this line.
Pin 46, GNDAB* . Ground, Analog Back-end
This pin has to be connected to the analog ground.
No supply current for the digital stages should flow
through this line.
Pin 47, VRD . DAC Reference Decoupling (Fig. 17)
Via this pin the DAC reference voltage is decoupled
by an external capacitor. The DAC output currents
depend on this voltage, therefore a pulldown transistor
can be used to shut off all beam currents. A d-
ecoupling capacitor of 4.7⎧F in parallel to 100 nF
(low inductance) is required.
Chassis M35&36 Service Manual
Pin 55, GNDS* . Ground, Standby
This is the ground reference for the standby circuitry.
Pins 56 and 57, XTAL1 Crystal Input and XTAL2
Crystal Output (Fig. 20)
These pins are connected to an 20.25 MHz crystal
oscillator which is digitally tuned by integrated shunt
capacitances. The CLK20 clock signal is derived from
this oscillator.
Pin 58, RESQ . Reset Input/Output (Fig. 21)
A low level on this pin resets the VCT 38xxA. The
internal CPU can pull down this pin to reset external
devices connected to this pin.
Pin 48, XREF . DAC Current Reference (Fig. 17)
External reference resistor for DAC output currents,
typical 10 k. to adjust the output current of the D/A
converters. (see recommended operating conditions).
This resistor has to be connected to analog g-
round as closely as possible to the pin.
Pin 49, 50, 51, AIN1.3 . Analog Audio Input
(Fig. 18)
The analog input signal from TUNER or SCART is
Fed to this pin. The input signal must be AC-coupled.
Alternatively these pins can be used as digital
I/O ports (Fig. 18’).
Pin 52,53, AOUT1AOUT2 . Analog Audio Output
(Fig. 19)
These pins are the analog audio outputs. Connections
to these pins must use a 680 ohm series resistor
as closely as possible to these pins. The output
signals are intended to be AC coupled. Alternatively
these pins can be used as digital I/O ports
(Fig. 18’).
Pin 54, VSUPS* . Supply Voltage, Standby
44 03.Mar.2003