Motorola EP350 User Manual

12-2 UHF1 Troubleshooting Tables: Troubleshooting Table for Synthesizer (UHF1)
12.2 Troubleshooting Table for Synthesizer (UHF1)
Table 12-2. Troubleshooting Table for Synthesizer (UHF1)
Symptom Possible Causes Procedure Corrective Action
Synthesizer Out of
Lock (No RX
Mode)
1. Defective 12.8 MHz
VCTCXO
Verify clock output FL701 Pin 3 is
12.8 MHz using high impedance
probe.
Repair/Replace FL701
2. 1/2VCC defective Verify FL701 Pin 1, U502–B Pin 5 &
U502–D Pin 14 voltage is 1.9V.
Troubleshoot: 1/2VCC circuitry
3. No RX–Enable Verify U101 Pin 71 (RX–EN1) is
high.
Verify Q304 collector voltage is
approximately 4.7V in RX mode
Check U101 operating
Troubleshoot: Q304 & Q305
circuitry
4. Check PLL–LD port Verify U101 Pin 27 is Low (Normal
Mode)
Verify U101 Pin 27 is swept from low
to high (Power Save Mode)
Troubleshoot: PLL circuitry.
Repair/Replace U701
Synthesizer Out of
Lock (No TX Mode)
1. Defective 12.8 MHz
VCTCXO
Verify clock output FL701 Pin 3 is
12.8 MHz using high impedance
probe.
Repair/Replace FL701
2. 1/2VCC defective Verify FL701 Pin 1, U502–B Pin 5 &
U502–D Pin 14 voltage is 1.9V.
Troubleshoot: 1/2VCC circuitry
3. No TX–Enable Verify U101 Pin 84(TX–EN1) is high
when PTT is pressed.
Verify Q407 collector voltage is
approximately 4.7V when PTT is
pressed (TX–EN2).
Check U101 operating
Check U101–Pin 85 is high/
Replace Q407/check LK2 is
short
4. Check PLL–LD port Verify U101 Pin 27 is Low (Normal
Mode)
Verify U101 Pin 27 is swept from low
to high (Power Save Mode)
Troubleshoot: PLL circuitry
Repair/Replace U701

Motorola EP350 Specifications

General

Channel Capacity	16 channels
IP Rating	IP54
Drop Resistance	1.2 meters
Frequency Range	VHF: 136-174 MHz, UHF: 403-470 MHz
Battery Life	Up to 11 hours
Power Supply	7.5 V (Nominal)
Waterproof	Splashproof
Dimensions	127.6 x 62 x 42 mm (with standard battery)