Motorola ASTRO Digital XTL 5000 Detailed Service Manual page 185

Troubleshooting Charts: Troubleshooting Tables
Table 5-2. XTL 5000 Troubleshooting Table (700–800 MHz, 380-470 MHz and 136-174 MHz) (Continued)
Symptom
Radio Dead, Display Clocks
Lights Up
A+
No RX Audio/ Controller Block
Receive Does not
Unsquelch
Regulators
ABACUS Circuit
(380-470 MHz,
450-520 MHz)
6881096C74-B
Check Section Troubleshooting Procedure
Check for 32 kHz clock at
U0102-4, and 16.8 MHz clock at
C0106, C0911
Check A+ to the Control Head
J0401-19, 20
(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
See description for No VOCON
Powerup
• Check for 20 kHz Frame Sync
pulse signal at testpoint FS
(U5002-31)
• Check for 1.2 MHz Clock
square wave at testpoint
CLKOUT (U5002-28)
• Check for random data pattern
at testpoint DOUTA (U5002-29)
• Check for Clock Oscillator at
R5025 (18 MHz)
• Check for Local Oscillator at
C5058 (71.1 MHz or 75.6 MHz)
Component
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.
• 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
• Absence of signal causes no
receive. Possible U5002
(ABACUS) failure or U0001
(Microprocessor Board) failure
• Absence of signal causes no
receive. Possible U5002
(ABACUS) failure or U0001
(Microprocessor Board) failure
• Absence of signal causes no
receive. Possible U5002
(ABACUS) failure or U0001
(Microprocessor Board) failure
• Absence of Clock signal
causes no receive. Possible
U5002 (ABACUS), Clock VCO,
or U0001 (Microprocessor
Board) failure
• Absence of LO signal causes
no receive. Possible U5002
(ABACUS), or LO VCO
May 25, 2005
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