Nokia RM-155, 2366i Vari Antenna Description and Troubleshooting

Nokia Customer Care
2366i (RM-155) Mobile Terminals
Antenna Description and
Troubleshooting
Issue 2 - February 2007 Company Confidential
2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care

Contents Page

Introduction ..................................................................................................................................................... 3
CDMA Antenna Assembly............................................................................................................................. 4
Remove the CDMA Antenna Assembly ..................................................................................................5
Circuit Description ......................................................................................................................................6
Damaged RF Feed Contact ........................................................................................................................ 6
Damaged RF Connector .............................................................................................................................7
GPS Antenna .................................................................................................................................................... 8
Expose the GPS Antenna Circuits ...........................................................................................................8
Malfunctions .................................................................................................................................................8
GPS Matching Components ......................................................................................................................9
Bluetooth Antenna...................................................................................................................................... 11
2366i (RM-155)
Nokia Customer Care Antenna Description and Troubleshooting

Introduction

This chapter addresses potential failures that affect antenna performance of the 2366i mobile terminals and discusses methods for correction of these failures. There are three serviceable antennas used in the 2366i mobile terminal:
CDMA antenna (a dual-band stub antenna)
GPS antenna (mounted to the main PWB)
Bluetooth antenna (a printed trace on the main PWB)
The following sections describe these antennas and their connections to the mobile terminal components.
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2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care

CDMA Antenna Assembly

You can disconnect the dual-band CDMA antenna assembly. Partial disassembly of the mobile terminal is required to remove and replace the CDMA antenna assembly. (See the Disassembly and Assembly chapters for instructions.) When installed, a T-shaped locking tab on the antenna assembly engages two locking ramps molded into the D-cover and an electrical spring clip contact connects to a pad on the main PWB. Figure 1 shows the antenna assembly and its mounting arrangement.
Locking ramps
Figure 1: CDMA Antenna Assembly and mounting arrangement
Antenna pogo pins
Spring Clip Contact
Locking Tab
Antenna Contact Pad
CDMA Antenna Assembly
Figure 2: Antenna Contact Pad
2366i (RM-155)
Nokia Customer Care Antenna Description and Troubleshooting

Remove the CDMA Antenna Assembly

Perform the following steps to remove the CDMA Antenna Assembly:
1. Remove the battery cover. Press down on the cover while sliding it away from the body of the mobile terminal.
Figure 3: Removal of the Battery Cover
2. If installed, remove the battery.
3. Remove the RF grommet.
Figure 4: Antenna Grommet
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2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care
4. Remove the antenna. Use a dental pick to lift the retaining latch. Do not cause damage to the contacts.
Figure 5: Disconnection of the Antenna (1)
Figure 6: Disconnection of the Antenna (2)

Circuit Description

Refer to Figure 7. The output of the diplexer is fed through RF connector X7300 and through a zero-ohm resistor R7358 to the antenna contact pad on the main PWB. The RF choke L7303 drains static charges to ground, protecting the preceding circuitry from electrostatic damage (ESD). If a test cable is inserted into RF connector X7300, a mechanical switch is opened, disconnecting diplexer Z7302 from the antenna contact pad.

Damaged RF Feed Contact

The CDMA antenna assembly has a metal spring clip that makes contact with an antenna contact pad on the main PWB. If the spring clip is damaged such that it does not make contact with the pad, then replace the CDMA antenna assembly. If the pad is damaged, replace the main PWB. If the contact does not make good contact with the pad, then the antenna gain is reduced by -25 dB.
2366i (RM-155)
Nokia Customer Care Antenna Description and Troubleshooting

Damaged RF Connector

The RF connector contains a switch. If this switch fails, there is a loss of continuity between the input to the diplexer and the CDMA antenna, resulting in a gain reduction of approximately -25 dB.
Measure the DC continuity through the CDMA RF connector with no cable connected. See Figure 7 and Figure 8 for the location of this connector. If there is no DC continuity, replace CDMA RF connector X7300.
CDMA RF Connector
Antenna Contact Pad
CDMA RF Connector
Figure 7: CDMA Antenna Circuit
Figure 8: D-cover Removed
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2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care

GPS Antenna

The GPS Antenna is a ceramic chip soldered onto the Main PWB. The antenna must be mounted exactly as shown in the figure, or the antenna does not operate correctly. RF choke L6253 acts as an ESD protection, draining static charges to ground. C6256 tunes the antenna. When a test connector is inserted into RF Connector X6250, an internal switch disconnects the filter from the GPS antenna circuits.
GPS RF Connector
Filter
Figure 9: GPS Antenna Circuit

Expose the GPS Antenna Circuits

Refer to the Disassembly chapter to remove the D-cover and expose the GPS antenna circuits for troubleshooting.

Malfunctions

Figure 10 shows the mounting orientation of the GPS antenna and the matching circuits.
Check the following items to troubleshoot the GPS antenna circuits:
If the GPS antenna looks damaged, or is missing, install a new antenna.
Check the orientation of the antenna against that shown in Figure 10, and correctly install a new antenna if the orientation is not correct.
The RF connector contains a switch. If this switch fails, there is a loss of continuity between the input to the Filter and the GPS antenna, resulting in a gain reduction of approximately -20 dB. Measure the DC continuity through the GPS RF Connector with no cable connected. See Figure 11 for the location of this connector. If there is no DC continuity, replace GPS RF connector X6250.
RF ChokeTuning Capacitor
2366i (RM-155)
Nokia Customer Care Antenna Description and Troubleshooting
GPS Antenna
Ground
Figure 10: GPS Antenna and mounting arrangement
Figure 11: GPS RF Connector (GPS Antenna removed)

GPS Matching Components

Figure 12 shows the impedance-matching components for the GPS antenna circuit.
Ensure that these components are properly installed and that the correct part number is used, as value and size are critical.
Feed
Ground
GPS RF Connector
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2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care
6,2 nH, NMP code 3649051
2.2 pF NMP code 2320523
Front Side
Rear Side
Figure 12: Matching components—GPS Antenna circuit
2366i (RM-155)
Nokia Customer Care Antenna Description and Troubleshooting

Bluetooth Antenna

The Bluetooth antenna, shown in Figure 13, is mounted on the main PWB. A 6.8 nH inductor is used as a tuning component. Ensure that the antenna is correctly mounted on the PWB. If the antenna is reversed, it does not function.
CDMA antenna matching network
GPS pogo pins
Figure 13: Main PWB - Bluetooth Antenna
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2366i (RM-155) Antenna Description and Troubleshooting Nokia Customer Care
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