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Ericsson LBI-38701, Руководство по обслуживанию, Страница: 19 / 23

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IF Tuning

1.

Monitor J501 with an AC voltmeter and inject an on
channel signal at the antenna jack modulated with a 60Hz
ramp at 5 kHz deviation.

2.

Adjust L504, L506, and L507 for a peak on the AC
voltmeter. Adjust the level of the signal generator to keep
the signal at J501 out of limiting (approximately -
65dBm).

3.

Repeak the coils.

Quadrature Detector Adjustment

1.

Inject a strong on channel signal at the antenna jack
modulated with a 1 kHz tone at 3 kHz deviation.

2.

Monitor the VOL/SQ HI output at J705-3 with an AC
voltmeter and adjust L509 for a peak on the meter.

Receiver Audio Level

1.

Inject a strong on channel signal at the antenna jack
modulated with a 1 kHz tone at 3 kHz deviation.

2.

Monitor VOL/SQ HI J705-3 with an AC voltmeter and
adjust R513 for a reading of 150 mVrms. Alternatively,
the RX AUDIO jack of the test box can be monitored
when the Volume has been adjusted to VOL=10. R513
may be adjusted for a reading of 215 mVrms. A+ supply
current should be less than 600 mA.

Sidetone Adjustment

The following adjustment requires duplex operation.

The RF signal generator must be isolated from the trans-
mitter RF power by connecting a 15 watt 30dB attenuator
or other isolation device in series with the RF signal
generator.

1.

Inject a strong on channel signal modulated by 1 kHz
tone at 3 kHz deviation at the RF input.

2.

Turn the RX audio on (FCN 0 2) and set the volume at
maximum. Measure the RX audio output at the RX
AUDIO jack of the test box (J701-5) which should be
215 mVrms.

3.

Turn off the 1 kHz modulation while leaving on the RF
generator signal.

4.

Apply a 1 kHz tone to the TX Audio input at TX MOD
jack of the test box (J701-4). Turn on the TX audio (FCN
0 4) and key the transmitter (FCN 0 1). Adjust the 1 kHz
tone level for 3 kHz deviation.

5.

Turn on the RX audio (FCN 0 2) and rekey (FCN 0 1).
Measure the RX audio output and adjust R624 on the
Audio Board for a null. The null should be less than 27
mVrms (< -18 dB down from the 215 mVrms reference
taken above). Push END to unkey the transmitter.

TRANSMITTER VERIFICATION

Place the radio in the test mode for the following tests

(FCN A).

Transmit Frequency

Key the transmitter (FCN 0 1) and measure the trans-

mit frequency (default test mode channel is the first fre-
quency in the trunk frequency set from which test mode
was entered). The measured frequency should be within

±

250 Hz. (Push END to unkey the transmitter.)

Transmit Power

Select channel 649 (CLR 6 4 9 CLR) at 814.0000

MHz. Key the transmitter (FCN 0 1). Power should be a
minimum of 10 watts. (Push END to unkey the transmit-
ter.)

Modulation Limiting

1.

Apply a 1 kHz tone at 300 mVrms to the TX AUDIO
input of the test box or J701-4.

2.

Select channel 649 (CLR 6 4 9 CLR) at 814.0000 MHz.
Turn on the TX audio (FCN 0 4). Turn on the channel
guard tone (FCN 2 5) which also keys the transmitter.

3.

The measured deviation should be 4.2 

±

0.2 kHz. (Push

END to unkey the transmitter.)

NOTE

The external speaker must be disabled otherwise
higher supply currents will be measured.

NOTE

A 1 kHz tone may be used if a 60Hz ramp is not
available

LBI-38701

19

Содержание LBI-38701

Страница 1: ...er 4 To Remove The Duplexer Assembly 4 To Remove The RF Board 4 To Remove The Audio Board 5 To Remove The Front Cap Assembly 5 To Remove The Logic Board 5 To Remove The Duplexer Interface Board 7 To Remove The System Board 7 To Remove The Handset Interface Board 7 Chip Component Replacement 7 To Remove Chip Components 7 To Replace Chip Components 7 Troubleshooting Procedures 8 Self Diagnostics Err...

Страница 2: ...ervice Aids 17 Transmitter Alignment 17 Receiver Alignment 18 Transmitter Verification 19 Receiver Verification 20 Diagrams Audio Signal Flow Diagram 21 Control Signal Flow Diagram 22 Power Distribution Diagram 23 Copyright March 1992 Ericsson GE Mobile Communications Inc LBI 38701 2 ...

Страница 3: ...tion When ground connections are not made directly to the battery the connection from the battery to vehicle chassis must be checked for low imped ance A high impedance may cause excessive voltage drops and alternator noise problems ELECTRICAL SYSTEM Check the voltage regulator and alternator or gener ator periodically to keep the electrical system within safe and economical operating limits Overv...

Страница 4: ...ures the duplexer assembly to the casting 3 The duplexer can now be removed by disconnecting the SMB connectors from the TX and RX inputs of the duplexer and disconnecting the TNC connector from the ANT port of the duplexer TO REMOVE THE RF BOARD A2 l Remove the top and bottom covers and the duplexer assembly from the radio refer to the procedures above 2 Refer to Figure 3 Pry off the friction fit...

Страница 5: ... by the clip TO REMOVE THE FRONT CAP ASSEMBLY l Remove the top and bottom covers of the radio 2 Remove the two M3 5 06 x 8 TORX screws 15 drive from both sides of the front cap and the TORX screw on the bottom of the front cap 3 Gently pull the front cap assembly away from the radio exposing the ribbon cable on the rear of the assembly TO REMOVE THE LOGIC BOARD A1 l Remove the top and bottom cover...

Страница 6: ...Figure 4 Top View Figure 3 Bottom View Without Duplexer LBI 38701 6 ...

Страница 7: ...s used PA module replacement is located in the RF Board manual Replacement of chip capacitors should always be done with a temperature controlled soldering iron operating at 700F 371C However DO NOT touch black metal film of the resistors or the ceramic body of capacitors with the soldering iron NOTE The metallized end terminations of the parts may be touched with the soldering iron without causin...

Страница 8: ...Board Analog to digital and digital to analog conversion of the RX and TX audio CAS squelch output signal to the Logic Board Conventional analog tone fil tering and processing Logic Board Routes signals between the RF Audio and Control Boards Contains the EEPROM for the radio personality Contains the main radio micro processor Accepts PTT from the micro phone Provides DPTT to turn on the transmitt...

Страница 9: ...T command to the RF Board If present then the problem is likely on the RF Board If the DPTT is not present the problem is likely on the Logic Board Low Tx Power Check the transmit frequency If its not OK check the synthesizer on the RF Board and the synthesizer load commands from the Logic Board If the commands are not present a problem on the Logic Board is likely If the Tx frequency is correct r...

Страница 10: ...st mode commands Modulate the generator with the correct tone sequence and busy tone If the test fails check the limited data output from the Audio board If the data is present the Logic Board may be faulty If the data is not present the Audio Board may be faulty Tx encode check Use FCN 08 for the encode test If the test fails the Audio or Logic Board may be faulty Look for proper tones to the Aud...

Страница 11: ...ng test mode will revert to the first programmed channel in the frequency set that was being scanned when test mode was entered Channel Frequency Select To select a channel other than the frequencies in the current trunked set press CLR followed by a 2 to 4 digit channel number 10 1208 followed by CLR The chan nels can be entered without leading zeros For example to select channel 12 enter CLR 12 ...

Страница 12: ...lume Up VOLUP The VOLUP command causes the radio to increment the volume setting by one step There are 16 possible steps The volume setting affects the receive audio and the audi ble user tones A visual prompt is seen in the display of the new volume setting ranging from 00 through 15 for exam ple VOL 04 Volume Down VOLDN The VOLDN command decrements the volume set ting A visual prompt is seen in ...

Страница 13: ... Tone 42 is the dial tone detect all channels busy tone Tones 1 through 39 are transmitted at a high deviation level while tones 40 through 42 are generated at a low deviation level GEMARC TONE TABLE All GEMARC tones numbers and their respective frequencies are provided in Table 1 below Increment Tone 3 The 3 command increments the tone number to the next GEMARC tone If tone 42 is displayed then t...

Страница 14: ...io On FCN 0 4 This FCN 0 4 function displays MICAUDON and transmits the signal present on the mic audio path during transmit Microphone Audio Off FCN 0 5 The FCN 0 5 function displays MICAUDOF and disables the mic audio path during transmit Transmit Standard Busy Tone FCN 0 6 The FCN 0 6 function checks the lock detect line of the synthesizer and displays UNLOCK if the synthesizer is out of lock O...

Страница 15: ...he normal mode it will decode the individual decode tone set and the selected group as well as groups 1 2 3 If one of the tone sets is decoded the display will be updated with the same name handle that the tone set has in trunked mode The radio then sounds either the single group decoded or dual individual decoded note alert The radio will then return to looking for the busy tone PTT or another fu...

Страница 16: ... if the check sum fails PROM OK is displayed if the test is successful TCXO Low Frequency Modulation Test FCN 2 3 The FCN 2 3 function checks the lock detect line of the synthesizer and displays UNLOCK if the synthesizer is out of lock Otherwise the radio displays DCG ENC keys the transmitter even if an unlock condition exists and continuously transmits a 10 HZ square wave useful in setting the lo...

Страница 17: ...cing both sides of the audio board while powered up 19A705235P2 Service Cable provides an ex tension two feet between the System and Control Boards Not required for most servicing if ex isting cable is not looped through the front of the radio assembly 19A801348P4 Provides a two foot extension be tween the 9 pin D connectors on the Logic and Control boards Permits servicing all assemblies in the F...

Страница 18: ... Set 1 While on channel 649 key the transmitter FCN 0 1 and adjust R111 in the power control circuit for 11 watts 2 Push END to unkey the transmitter RECEIVER ALIGNMENT Frequency Set 1 Verify that the transmitter is on frequency as described in the transmitter alignment above 2 Inject a strong unmodulated on channel signal 60dBm at the antenna input J101 3 Monitor J501 with a frequency counter and...

Страница 19: ...t the RX AUDIO jack of the test box J701 5 which should be 215 mVrms 3 Turn off the 1 kHz modulation while leaving on the RF generator signal 4 Apply a 1 kHz tone to the TX Audio input at TX MOD jack of the test box J701 4 Turn onthe TX audio FCN 0 4 and key the transmitter FCN 0 1 Adjust the 1 kHz tone level for 3 kHz deviation 5 Turn on the RX audio FCN 0 2 and rekey FCN 0 1 Measure the RX audio...

Страница 20: ...pply a strong 60 dBm on channel signal modulated with a 1 kHz tone at 3 kHz deviation 2 Set the volume at maximum Monitor the RX AUDIO jack on the test box or J705 6 The output level should be approximately 215 mVrms with less than 5 distortion Duplex Receive Sensitivity The following test requires a completely assembled radio with all covers in place A calibrated attenuator pad 30 dB 15 watts mus...

Страница 21: ...AUDIO SIGNAL FLOW DIAGRAM LBI 38701 Figure 6 Audio Signal Flow Diagram 21 ...

Страница 22: ...LBI 38701 CONTROL SIGNAL FLOW DIAGRAM Figure 7 Control Signal Flow Diagram 22 ...

Страница 23: ...POWER DISTRIBUTION DIAGRAM LBI 38701 Figure 8 Power Distribution Diagram 23 ...

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