Nokia RM-57 Service Manual page 241

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3.1.1.1.1.1 Ferrite inductor L7503 ok?
• Check that component is in place and solder joints are ok
• Measure voltage from the both ends of L7503. Is it faulty or is there short circuit in RF end?
• Disconnect the power supply from the phone and use an ohmmeter to check that inductor is
conducting DC.
3.1.1.1.2 RFBUS signals ok?
• GSM receiver has to be active before RFBUS signals can be measured. Procedure is explained
in section "GSM RX chain activation for manual measurements". Also WCDMA/GSM transmitter
and WCDMA receiver activation can be used for the measurement but then RFBUS -signals
don't necessarily look like in figures mentioned below.
• Measurements can be performed with an oscilloscope and a probe. Check all five RF BUS
signals:
RFBUSDAT: Connect the probe to J7504. Typical RFBUSDAT -signal is shown in section 6.5.9.3
-
"RFBUSDAT (GSM
RFBUSCLK: Connect the probe to J7505. Typical RFBUSCLK -signal is shown in sections 6.5.9.1
-
"RFUSCLK (GSM
RFBUSENA: Connect the probe to J7506. Typical RFBUSENA -signal is shown in section 6.5.9.2
-
"RFBUSCLK and RFBUSENA (GSM
RXRESETX: Connect the probe to J7515. RXRESETX -signal is a constant 2 V DC-signal after GSM
-
transceiver has been activated the first time after phone boot up. The level of this signal
should be about 0 V before transceiver activation.
TXRESETX: Connect the probe to J7517. TXRESETX -signal is a constant 2 V DC-signal after GSM
-
transceiver has been activated the first time after phone boot up. The level of this signal
should be about 0 V before transceiver activation.
3.1.1.1.2.1 RAP3G (or Vinku or Hinku) faulty?
• RAP3G (D2800) cannot be replaced.
3.1.1.1.3 Vinku (N7501) regulator voltages VREG1, VREG2 ok?
• GSM transmitter has to be active before VREG1 and VREG2 voltages can be measured.
Procedure is explained in section "Transmitter troubleshooting."
• Measurements can be done with an oscilloscope and a probe.
• VREG1: Connect the probe to C7543
• VREG2: Connect the probe to C7548 (or C7547)
RX)"
RX)" and 6.5.9.2 "RFBUSCLK and RFBUSENA (GSM
RX)"
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Appendix A: RF Troubleshooting
RX)"
A-23