Motorola XTL 1500, Detailed Service Manual, Page: 165 / 452

June 15, 2005 6815854H01-A
5-4 Troubleshooting Charts: Troubleshooting Tables
Radio Dead, No
Display, No LED
Backlighting (cont.) Flex/Control Head Check for SW_B+_CH at J0401-
17, TP0413.
Check for all voltages in CH;
1.55V, 1.88V, 2.8V, 3.3V, 5V and
UNSW_VCC (3.0V).
Check for Board ID resistors on
CH. Should match schematics.
Absence of signal may indicate
failure with flex, control head
Absence/mismatch warranats
replacement to correct location.
Clocks
A+
Check for 32 kHz clock at
U0102-4, and 16.8 MHz clock at
C0106, C0911
Check A+ to the Control Head
J0401-19, 21
Presence of signals may indicate
failure with U0001
(Microprocessor Board).
Absence of signals may indicate
failure with U0102 (Inverter) or
with FGU reference oscillator
circuit
• Absence of voltage F0400 may
be blown.
No RX Audio/
Receive Does not
Unsquelch Controller Block (Inject 1 kHz tone, 3 kHz
deviation into radio antenna, set
volume to rated audio.
• Check for speaker leads
shorted to ground, or at U0204-
4, 6.
• Check for > 30 mV rms audio
at audio PA input, U0204-1,9.
• Check for > 30 mV rms audio
at U0206-8 or TP0205.
• Check for > 30 mV rms audio
at U0210-6 or U0200-2.
• Check that U0204-8 is >10 V
• Short may indicate failure with
VR0400, VR0412, or U0204
• Presence of signal may
indicate failure with U0204
(Audio PA)
• Presence of signal may
indicate failure with U0206
(Log-POT)
• Presence of signal may
indicate failure with U0210
(MUX); Absence of signal may
indicate failure with U0200
(CODEC), or U0001
(Microprocessor Board)
• Absence of >10V may indicate
failure with Q0200 or U0001
Regulators See description for No VOCON
Powerup
Table 5-2. XTL 1500 Troubleshooting Table (700–800 MHz, 380-470 MHz and 136-174 MHz) (Continued)
Symptom Check Section Troubleshooting Procedure Component