Tait TM8110 Service Manual

TM8100/TM8200 Service Manual CODEC and Audio Fault Finding 381
© Tait Electronics Limited June 2006
13 CODEC and Audio Fault Finding
Fault Conditions This section covers the diagnosis of faults in the CODEC and audio
circuitry. There are five conditions that indicate a possible fault in the
circuitry:
■ no speaker audio or speaker audio is distorted
■ no speaker audio at auxiliary connector
■ receiver does not operate
■ no transmit modulation or modulation is distorted
■ no transmit modulation despite modulation at auxiliary connector
In the first
case regarding the speaker audio, the green STATUS LED will be
operating correctly and all unmute criteria will be satisfied. In the second
case the receiver will be operating normally. In the third
case the assumption
is that the receiver and power-supply circuitry were checked and no faults
were found. In the fourth
case regarding the transmit modulation, the radio
will be transmitting the correct amount of RF power. In the fifth
case the
transmitter will be operating normally.
Fault-Diagnosis
Procedures
The procedures for diagnosing the above faults are given below in the
following sections. In each case, however, first carry out the tasks of “Power
Supplies” on page 382. Also note that the conditions concerning the
auxiliary connector can both occur at the same time. In this case carry out
both “No Speaker Audio at Auxiliary Connector” on page 391 and “Faulty
Modulation Using Auxiliary Connector” on page 402.
CCTM Commands The CCTM commands required in this section are listed in Table 13.1.
Full details of the commands are given in “Computer-Controlled Test
Mode (CCTM)” on page 118.
Table 13.1 CCTM commands required for the diagnosis of faults in the CODEC and audio circuitry
Command Description
21 Unmute received audio
32 Set radio in receive mode
33 Set radio in transmit mode
110 x Set level x (in range 0 to 255) of audio volume
323 x y Generate audio tone AUD TAP IN at tap point x of tap type y
324 x y Output audio signal at tap point x of tap type y to AUD TAP OUT
400 x Select channel with channel number x

Tait TM8110 Specifications

General

Brand	Tait
Model	TM8110
Category	Radio
Language	English