Specifications

CA10 Course Notes
Sharp Electronics (UK) Limited
CE Technical Support GroupPage 44
Indicating Devices
Figure 41 : Stereo and OPC LED Drive Circuit
There are three indicating devices used within the CA10 chassis. The first of these is the standby
indicator, which is a neon connected across the live and neutral mains input, after the mains switch. This
will illuminate whenever mains is applied to the set.
The second indicator is the stereo LED. Whenever a stereo broadcast is being received ( a NICAM signal
is being decoded ), the audio processor will communicate with the system control microprocessor over
the I C bus 1 line and instruct it to give a high on pin 9 ( STLED ) so that LED301 illuminates. Note that
2
when a stereo input is fed into the receiver via one of the SCART inputs or the front AV input, the stereo
LED will not illuminate.
Thirdly there is the OPC indicator. This LED, LED302 is turned on by a high level on pin 14 ( LEDOPC
) of IC101. The OPC function is turned on and off by selection of the picture menu via the remote control.