LBI-38557A Mobile Communications SERVICE SECTION FOR MPI-II VHF PERSONAL RADIO Ericsson GE Mobile Communications Inc. Mountain View Road•Lynchburg, Virginia 24502 Copyright January 1991, Ericsson GE Mobile Communications, Inc. Maintenance Manual Printed in U.S.A.
LBI-38557 LBI-38557 INTRODUCTION TABLE OF CONTENTS Page INTRODUCTION................................................................................................................................. 1 DISASSEMBLY PROCEDURE .......................................................................................................... TOOLS NEEDED.......................................................................................................................... BATTERY ...................................
LBI-38557 LBI-38557 BNC CONNECTOR 1. Remove the No. 3-48 x .125 setscrew (D) using a 0.050 hex tool. 2. Unsolder the BNC center pin from the antenna contact. 3. Remove the BNC connector. UDC COVER Remove the M2.5-0.45 screw using a flat blade screwdriver or the edge of a coin. TOP COVER 1. Pull off the two knobs from the ON/OFF/VOLUME and the Squelch control. 2. Remove the Spanner nuts (E) using a Spanner Tool ST2311. 3. Remove the 1/4-40 (F) nut using a 5/16 wrench. 4.
LBI-38557 LBI-38557 Several tests are presented which will help isolate a possible RF or control circuit problem. The control circuits, which are located on the T/R Board, contain no adjustments and there is no alignment required for the control circuits. See the Troubleshooting section for test information if a problem is suspected in the control circuits. TEST EQUIPMENT General Equipment 1. RF Generator (136-174 MHz) 2. Wattmeter (5 watts) 3. Ammeter (2 amperes) 4. Distortion Analyzer 5.
LBI-38557 LBI-38557 Figure 4 - Location of Tuning Controls and Test Points 4
LBI-38557 2. 3. 4. LBI-38557 Check power on the lower channel. Adjust C124 in the direction that increases power output to a level half way between the initial lower and upper channel levels. Recheck the upper channel power. If the upper channel power is reduced, reset to the previous level by adjusting C126. Repeat this procedure until the power out on both channels is equal (±.1W).
LBI-38557 3. 4. LBI-38557 Check for proper operation of the synthesizer. There should be approximately 0 dBm drive level on the SYNTH output line for proper transmit operation. If a Syntheiszer problem is suspected, following the suggestions in Troubleshooting Synthesizer section. Check to see that Channel Guard signal is at the output of the post limiter filter, U301-A pin 1, or at the TX MOD output.
LBI-38557 LBI-38557 D.C. Analysis Bilateral Switch U205 CAUTION Battery voltage (7.5/10 Volts, B+) is supplied to a 5.4 volt regulator circuit consisting of transistors Q801, Q802 and Q803. Diode regulator U801 provides a 2.5 volt reference for this circuit. Battery voltage (B+) is also supplied to the Synthesizer Board for isolation amplifier U206. the 5.4 volt regulator supplies both the synthesizer and most of the Transmit and Receive circuits.
LBI-38557 LBI-38557 SURFACE MOUNT COMPONENT REPLACEMENT 1. "Tin" one terminal end of the new component and the corresponding pad of the PWB. Use as little solder as possible. 2. Place the component on the PWB pads, observing proper orientation for capacitors, diodes, transistors, etc. 3. Simultaneously touch the "tinned" terminal end and the "tinned" pad with the soldering iron. Slightly press the component down on the board as the solder liquifies.
LBI-38557 2. A full charge cycle using an appropriate Ericsson GE charger. 3. This procedure should be repeated again. Performing the rated discharge and charge cycle at least twice should sufficiently restore the battery. LBI-38557 MODIFICATION INSTRUCTIONS (Alternate IF Option) 3. To install the Alternate IF Option, follow the instructions shown below:. 1. Remove 2nd oscillator crystal unit Y501 and install 45.755 MHz crystal unit (19B233066G18) 2 Remove 1st IF crystal filters Z501 and Z502.
