Motorola ASTRO Digital XTL 5000 Detailed Service Manual page 189

Troubleshooting Charts: Troubleshooting Tables
Table 5-3. XTL 5000 Troubleshooting Table (136-174 MHz, 380-470 MHz and 450-520 MHz Mid Power)
Symptom
No RX Audio/ Controller Block
Receive Does not
Unsquelch
Regulators
ABACUS Circuit
(380-470 MHz,
450-520 MHz)
6881096C74-B
Check Section Troubleshooting Procedure
(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
• 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
5-9