Motorola Astro XTL 1500 - Table 4-13. Test Mode Channels (700-800 Mhz); Table 4-14. VCO Frequency Calculation and Switching Logic (700-800 Mhz)

6815854H01-A June 15, 2005
Troubleshooting Procedures: 700–800 MHz Main Board Troubleshooting 4-23
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 1500 VHF/UHF Range 1/UF Range 2/700–
800 MHz Mobile Radio Basic Service Manual (6815853H01) and step through each test
channel. Table 4-13 indicates the frequency and Aux logic level for each test mode channel.
In addition, Table 4-14 provides information about the frequency of operation for each VCO.
Table 4-13. Test Mode Channels (700–800 MHz)
Test
MODE
LV Frac-N
TX Logic
TX
Oscillator
TX Freq
MHz
LV Frac-N
RX Logic
RX
Oscillator
RX Freq
MHz
CHAN 1 AUX 1 U6754 osc1 762.0125 AUX 3 U6755 osc1 762.0625
CHAN 2 AUX 1 U6754 osc1 769.0125 AUX 3 U6755 osc1 769.0625
CHAN 3 AUX 1 U6754 osc1 775.9875 AUX 3 U6755 osc1 775.9375
CHAN 4 AUX 1 U6754 osc1 794.0125 AUX 4 U6755 osc2 851.0625
CHAN 5 AUX 1 U6754 osc1 805.9875 AUX 4 U6755 osc2 860.0625
CHAN 6 AUX 2 U6754 osc2 806.0125 AUX 4 U6755 osc2 860.0625
CHAN 7 AUX 2 U6754 osc2 823.9875 AUX 4 U6755 osc2 869.9375
CHAN 8 AUX 2 U6754 osc2 851.0125 AUX 4 U6755 osc2 851.0625
CHAN 9 AUX 2 U6754 osc2 860.0125 AUX 4 U6755 osc2 860.0625
CHAN 10 AUX 2 U6754 osc2 869.8875 AUX 4 U6755 osc2 869.9375
Table 4-14. VCO Frequency Calculation and Switching Logic (700–800 MHz)
MODE
Radio
Frequency
(MHz)
VCO
Frequency
Formula
VCO
Frequency
(MHz)
AUX
1
AUX
2
AUX
3
AUX
4
Rx 764.0125 -
775.9875
F(U6755 osc1) =
Fc + 73.35 MHz
837.3625 -
849.3375
Low Low HIgh Low
Rx 851.0125 -
868.9875
F(U6755 osc2) =
Fc - 73.35 MHz
777.6625 -
795.6375
Low Low Low HIgh
Tx (TA) 764.0125 -
775.9875
F(U6754 osc1) =
Fc
764.0125 -
775.9875
HIgh Low Low Low
Tx(RPTR) 794.0125 -
805.9875
F(U6754 osc1) =
Fc
794.0125 -
805.9875
HIgh Low Low Low
Tx(RPTR) 806.0125 -
823.9875
F(U6754 osc2) =
Fc
806.0125 -
823.9875
Low HIgh Low Low