Display Flashes "Fail 001; Table 4-13. Test Mode Channels (700-800 Mhz); Table 4-14. Vco Frequency Calculation And Switching Logic (700-800 Mhz) - Motorola ASTRO Digital XTL 5000 Detailed Service Manual

Troubleshooting Procedures: 700–800 MHz Main Board Troubleshooting
4.9.1

Display Flashes "FAIL 001"

This display indicates a synthesizer "out-of-lock" condition. The following information will help to
trouble shoot the frequency generation unit to the component level. Perform the following checks to
determine the mode of the Fail 001:
1. Determine if the "out-of-lock" condition occurs in either receive mode, transmit mode, or both.
Also, check other frequencies programmed in the unit if available.
2. To determine if the "out-of-lock" is frequency or VCO dependant, place the unit into RF TEST
Mode, as described in the ASTRO Digital XTL 5000 VHF/UHF Range 1/UF Range 2/700–
800 MHz Mobile Radio Basic Service Manual (6881096C73) and step through each test
channel.
In addition,
Test LV Frac-N
MODE TX Logic
CHAN 1 AUX 1
CHAN 2 AUX 1
CHAN 3 AUX 1
CHAN 4 AUX 1
CHAN 5 AUX 1
CHAN 6 AUX 2
CHAN 7 AUX 2
CHAN 8 AUX 2
CHAN 9 AUX 2
CHAN 10 AUX 2
Table 4-14. VCO Frequency Calculation and Switching Logic (700–800 MHz)
MODE Frequency
Rx 764.0125 -
Rx 851.0125 -
Tx (TA) 764.0125 -
Tx(RPTR) 794.0125 -
Tx(RPTR) 806.0125 -
6881096C74-B
Table 4-13 indicates the frequency and Aux logic level for each test mode channel.
Table 4-14 provides information about the frequency of operation for each VCO.
Table 4-13. Test Mode Channels (700–800 MHz)
TX
Oscillator
U6754 osc1
U6754 osc1
U6754 osc1
U6754 osc1
U6754 osc1
U6754 osc2
U6754 osc2
U6754 osc2
U6754 osc2
U6754 osc2
Radio VCO
Frequency
(MHz) Formula
F(U6755 osc1) =
775.9875 Fc + 73.35 MHz
F(U6755 osc2) =
868.9875 Fc - 73.35 MHz
F(U6754 osc1) =
775.9875 Fc
F(U6754 osc1) =
805.9875 Fc
F(U6754 osc2) =
823.9875 Fc
TX Freq LV Frac-N
MHz RX Logic
762.0125 AUX 3
769.0125 AUX 3
775.9875 AUX 3
794.0125 AUX 4
805.9875 AUX 4
806.0125 AUX 4
823.9875 AUX 4
851.0125 AUX 4
860.0125 AUX 4
869.8875 AUX 4
VCO
AUX
Frequency
1
(MHz)
837.3625 - Low
849.3375
777.6625 - Low
795.6375
764.0125 - HIgh
775.9875
794.0125 - HIgh
805.9875
806.0125 - Low
823.9875
RX RX Freq
Oscillator MHz
U6755 osc1 762.0625
U6755 osc1 769.0625
U6755 osc1 775.9375
U6755 osc2 851.0625
U6755 osc2 860.0625
U6755 osc2 860.0625
U6755 osc2 869.9375
U6755 osc2 851.0625
U6755 osc2 860.0625
U6755 osc2 869.9375
AUX AUX AUX
2 3 4
Low HIgh Low
Low Low HIgh
Low Low Low
Low Low Low
HIgh Low Low
May 25, 2005
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