TP9100 Service Manual Interface Fault Finding 141
© Tait Electronics Limited May 2005
Tas k 3 —
On/Off Switch
Faulty
Use this procedure if the radio fails to power up when the ON/OFF switch is
turned on. Before proceeding, make sure the fault is not related to one or
more of the following:
■ The battery is flat.
■ The LCD, LED or speaker is faulty. This can be misinterpreted as a faulty
ON/OFF switch if the radio does not exhibit normal startup behaviour.
■ The radio is inhibited (stunned).
■ The firmware is missing or corrupt.
If the
ON/OFF switch is faulty:
1. Remove the front panel and main-shield assembly.
2. Remove power from the radio.
3. Connect a resistance meter (such as a multimeter) across the test
points
TP900 and TP7V5SW. See Figure 7.1.
4. Measure the resistance with the switch in the on and off positions.
The correct ranges are below:
5. If the switch resistances are outside these limits, replace RV1. If the
resistances are within the limits then the on/off switch is not faulty;
go to “Power Supply Fault Finding” on page 149.
resistance when switch position ON: < 10Ω
resistance when switch position OFF: > 100kΩ
Figure 7.1 PCB layout of test points next to the switch pins of RV1
(bottom side)
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