After Sales
Technical Documentation
RAE/RAK–1N
Faultfinding/Disassembly
Page 8 – 30
Original, 05/97
4.2 Sound OK?
Listen to the sound, or optionally measure the output of the BUZZEROUT
with an oscilloscope. If the frequency and the level are correct, then
proceed to 4.2.1 otherwise the buzzer can be considered to be functional.
4.2.1 Disconnect SIM–Flex
In order to isolate the fault to the PDA module, disconnect the SIM–flex.
4.2.2 SPKR (pin 124)
Check the output of the pin 124 in the CPU (D130). Output should be a
square wave at a given frequency. If the signal is not toggling, go to
4.2.2.1 If the CPU controls the output ok, then proceed to 4.2.3
4.2.2.1 CPU Fault
If the CPU does not control the SPKR output, even though the buzzer test
is reported to be successful by the service software, then the CPU is likely
to be faulty.
4.2.3 BUZZEROUT OK?
If the BUZZEROUT is OK then proceed to 4.2.4, otherwise the fault is in
the buzzer driver circuitry; proceed to 4.2.3.1
4.2.3.1 Check Driver Circuitry
If the SPKR output stops before BUZZEROUT, check the circuitry
R142–R148, V132–V135, C138.
4.2.4 SIM–Flex OK?
Check if the SIM–flex, and all the connectors are OK. If the connection
from BUZZEROUT to the buzzer is OK, then proceed to the 4.2.5,
otherwise go to 4.2.4.1
4.2.4.1 SIM–Flex Fault
If the connection between the BUZZEROUT and the buzzer is broken,
check the SIM–flex along with the board–to–board connectors, CMT
module etc.
4.2.5 Buzzer Fault
If the CPU driven square wave is coming to the buzzer, but the buzzer
does not beep, then change the buzzer.
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