Circuit Diagram Of The Volume Control Circuitry; 14.11 Volume Control Faulty - Tait TM9100 Service Manual

14.11 Volume Control Faulty

The voltage level of the volume control potentiometer is converted to a
digital signal by an analog/digital converter, processed by the FPGA and
transmitted to the main board.
Note
Figure 14.15 Circuit diagram of the volume control circuitry
If the volume control works only intermittently, works only at full volume,
or does not work at all:
1.
2.
416 Fault Finding of Control Head
This section only describes faults to the volume control caused by
the control head, which has been established during the initial
servicing tasks by means of elimination test. For fault finding of
the amplifier circuitry of the main board, refer to xxx on page yyy.
ADC DO 3
FPGA
Check that the voltage between pins CW and WIP of the volume-
control potentiometer RV1 varies linearly between about 0V and
3.3V.
RV1: 0 to 3.3V
If the voltage is not correct, replace the potentiometer RV1
Send CCTM command 1010 to read the volume potentiometer.
No volume: reading 0 (1V)
Full volume: reading 255 (3.3V)
If the signal is not correct, remove can E100 and replace the
analog/digital converter U601.
If the signal is correct, replace the speaker.
3V3
8
VCC
6 VOL WIP DC
U601
CH1 DO
4
TM9100 Service Manual
© Tait Electronics Limited August 2005
3V3
R105
RV101