TM9100 Service Manual Circuit Descriptions 79
© Tait Electronics Limited August 2005
Auxiliary Audio
Output
The source for the auxiliary audio output signal CDC AUD TAP OUT is provided
by IC204 (
RAMPDAC ball). The DAC output of IC204 is low-pass filtered to
remove high-frequency artefacts. The low-pass filter, formed by IC201
(pins 1 to 3), R219, R220, R221, R224, C206, C208 and C210, is a third-
order Butterworth type with a cut frequency of approximately 12kHz.
The output of the low-pass filter is amplified by 6dB by a buffer amplifier,
IC201 (pins 5 to 7), and fed via R207 and R208 to drive the
CDC AUD TAP
OUT interface line. The DC bias for this signal path is provided by IC204 and
is approximately 1.2V when operational. The offset at
CDC AUD TAP OUT is
approximately 2.4V owing to the gain of the buffer amplifier.
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