Motorola EP450 Service Manual page 37

5-6
Table 5-3. Troubleshooting Table for Transmitter (Continued)
Symptom Possible Causes
No EXT MIC audio 1. Mic bias fault
2. Audio path fault
3. Defective audio acces-
sory
November 24, 2003
VHF Troubleshooting Tables: Troubleshooting Table for Transmitter
Procedure
Verify approx 1.8 V dc across EXT
MIC cartridge in TX mode. Verify
audio present (~10 mV rms) when
speaking into mic.
Verify mic audio present (~10 mV
rms) at U451-46.
Verify amplified mic audio present
(~200 mV rms) at U451-40.
Try another accessory.
Corrective Action
Check Q470. R475, R477,
L471. Check VR473, VR475,
D470 for shorts.
Check L471, C470.
Check/replace U451.
Replace defective accessory.
HKLN4216A