DP485 Service Manual
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9.Equipment for Maintenance and Test
1. Wireless general-purpose tester HP8920/8921
2. Digital multimeter
3. Regulated DC power supply
10.Troubleshooting
A. Check the battery. If it is low, charge or replace it.
B. The Power key does not work well. Replace the key.
C. The CPU does not work well. Replace it with a new IC19.
A. Make sure the channels the both radios communicate on are of the
same frequency.
B. The radios use different CTCSS/DCS signaling codes. Set the
same one via PC.
C. Out of communication range.
A. The antenna has bad contact. Screw up the antenna connector.
B. Sensitivity is low. Fine tune the “debugging mode”.
C. The squelch level is too high, so that squelch cannot be enabled.
Set a lower level via PC.
D. The Q3 does not work well. Replace the 2SC3356.
Red light on during
transmitting,
but receiver hears
no voice
A. The tube power amplifier outputs no power. Replace with a new
amplifier.
B. The microphone does not work well. Replace with a new
microphone.
Green light on during
receiving,
but cannot hear
voice
A. The speaker does not work well. Replace with a new speaker.
B. The audio amplifier IC5 does not work well. Replace with a new
TDA8547.
Check the settings of volume and MIC gain via the PC Tool.