CCS Technical Documentation RH-25 Series Transceivers Troubleshooting - RF Issue 1 10/2003 Confidential ©Nokia Corporation
RH-25 Troubleshooting - RF CCS Technical Documentation Contents Page No Transceiver Troubleshooting ......................................................................................... 3 Receiver Troubleshooting ............................................................................................3 General instructions for RX troubleshooting ............................................................ 3 Path of the received signal ................................................................
RH-25 Troubleshooting - RF CCS Technical Documentation Transceiver Troubleshooting The first thing to do when you are encountered with a problem is to carry out a thorough visual check of the module. Make sure that: • there are no mechanical damages • the solder joints are OK Note: Before changing anything, ALL SUPPLY VOLTAGES AND THE SYSTEM CLOCK / SLEEP CLOCK should be checked.
RH-25 Troubleshooting - RF CCS Technical Documentation Fault finding charts for receiver chain AMPS Apply 881.49MHz = ch 383 -116dBm, 8kHz dev, 1kHz sine to external RF connector (X900) Y Connect HS to cellular tester, open AF: 1kHz sine meas SINAD AF:>12dB Y AMPS RX chain OK N Start troubleshooting N Start troubleshooting N Check UHF Vc (from C773) V: 1.8 ... 2.1V Y Check RXVHF Vc (from C720) V: 0.7 ... 1.3 Y Apply 881.
RH-25 Troubleshooting - RF CCS Technical Documentation Check input level at diplexer (Z907) N Change EXT RF connector N Change diplexer (Z907) N Change duplex filter (Z906) NOTE: Check all soldering and components in antenna circuit before changing. Y Check input level at duplex filter NOTE: Check all soldering and discrete components of front end.
RH-25 Troubleshooting - RF CCS Technical Documentation Check RF level at RX IF filter input at 135.54MHz N Check RF level at J751 and J752 at 2034.06MHz N Start synthesizer troubleshooting Y NOTE: Check all discrete components and voltages around TACO. Change TACO (N801) Check RF level at RX IF filter output at 135.54MHz N Change RX IF filter (Z830) N Check RF level by L730 without having electrical contact at 271.
RH-25 Troubleshooting - RF CCS Technical Documentation TDMA800 Since the same physical signal path is used for both analog and digital modes at the lower band, there is no need for additional troubleshooting in the digital mode. So if the digital mode at the lower band is not working properly, start the analog mode troubleshooting. TDMA1900 (only dualband) Only EXT RF connector –> 1st IF needs separate troubleshoot at upper band. After down conversion (RF –> 135.
RH-25 Troubleshooting - RF CCS Technical Documentation Check input level of diplexer (Z907) N Change EXT RF connector N Change diplexer (Z907) NOTE: Check all soldering and components in antenna circuit before changing. Y Check input level of duplex filter NOTE: Check all soldering and discrete components of front end. Y Check RF level at LNA input (at duplex filter RX output port) N Change duplex filter (Z962) N Check voltage at C854 out (V850 in). V: about 2.
RH-25 Troubleshooting - RF CCS Technical Documentation Y Check RF level at MIX1_B input N Change RX1900 band filter N Check RF level at J751 and J752 at 2095.56MHz Y Check RF level at RX IF filter input at 135.
RH-25 Troubleshooting - RF CCS Technical Documentation TDMA1900 (ONLY DUALBAND) UEM TX I/Q DA-converters -> I/Q modulator and Digital gain step amplifier (TACO) -> IFBPF -> Upconverter+driver (TACO) -> Balun->BPF -> PA -> Coupler (Power detector) -> Duplex-filter -> Diplexer -> EXT RF-connector -> Antenna Fault finding charts for the transmitter AMPS Page 10 1 Start the Phoenix software and set the phone to analog mode by using RF Test UI. 2 Set the channel to 383 and the power level to 2.
RH-25 Troubleshooting - RF CCS Technical Documentation AMPS, PL2, CH383 Visual check of TX -PA -TX SAW -Duplex filter -Passive components OK Start synthesizer troubleshooting OK Check supply voltages -VR2 -VBATTRF -VR5 -IPA1 NOK Check UEM and UPP (Baseband) NOK Check UEM (Baseband) NOK Change TACO or Z960 NOK Change TACO OK Check TX I/q signals Test points J901 ... J904 OK Check Z960 input and output power out:-20dBm+3/-6dB IL:2dB OK Check TX RF (836.
RH-25 Troubleshooting - RF CCS Technical Documentation Check TX SAW input and output power IL:-3dB NOK Change TX SAW filter Z905 or T961 NOK Change PA NOK Change N930 NOK Change Z906 or RF connector OK Is ltot 700...900mA? Check PA output power and gain. Output power: dBm Gain: ~30 OK Check PWRDET insertion loss IL<0.3dB OK Check duplexer (Z906), diplexer (Z907), and RF connector (X900) insertion loss Dupl IL ~2.2 Dipl ~0.35 RF conn ~0.
RH-25 Troubleshooting - RF CCS Technical Documentation TDMA1900 (only dualband) TDMA1900 mode and DAMPS mode have a common RF modulator. TDMA1900, PL2, CH1000 Is TDMA800 mode OK? NOK Start AMPS troubleshooting OK Start synthesizer troubleshooting OK Check supply voltage -VR2 -VBATTRF -IPA2 NOK Check UEM and UPP (Baseband) NOK Change TACO NOK Change TACO NOK Change T960 or Z961 OK Check TX IF input power (180.54MHz) IF: -20 dBm +3/-6dB OK Check TX RF (1879.
RH-25 Troubleshooting - RF CCS Technical Documentation Is ltot 350...450mA? Check PA output power and gain. Output power: ~29dBm Gain: ~30dB NOK Change PA (N960) NOK Change PWRDET (N930) NOK Change Z906 or Z907 or RF connector OK Check PWRDET (N930) insertion loss IL<0.3dB OK Check duplexer (Z906), diplexer (Z907), and RF connector (X900) insertion loss Dupl IL ~2.2dB Dipl ~0.35dB RF conn ~0.
RH-25 Troubleshooting - RF CCS Technical Documentation Power control loop The power detection is done with the Power detector module and power control is done inside the TACO. Power detection is basically similar for both bands, except that both bands have their own coupler. Is PWRDET vs. output power OK? (See chart below) N Check VR2 and RFTEMP. Check C930, C931, and PWRDET module. N Check UEM (Baseband) NOTE: See PWRDET vs. Output power curve Y Is DAC value vs.
RH-25 Troubleshooting - RF CCS Technical Documentation Synthesizer Troubleshooting There are four oscillators generating the needed frequencies for RF section. A 19.44 MHz VCTCXO is used as a reference signal oscillator, 2 GHz UHF VCO with loop filter circuit is used for RX and TX channel selection, TX VHF and RF VHF are for TX modulator and 2nd RX mixer locals generation. The VHF synthesizers are integrated in TACO, but have external VCO coils and loop filters. RX VHF frequency is fixed to 271.
RH-25 Troubleshooting - RF CCS Technical Documentation RX VHF The RX VHF signal is used to generate receiver Intermediate frequency. RX VHF has one fixed frequency (271.08 MHz). Operating frequency is locked in Phase locked loop. RX VHF PLL output signal is integrated in TACO. There are only four external components, VCO coil (L730) and loop filter components C740, C741, and R741. 3 Replace TACO OK 2 No 1 START HERE! Yes Is frequency locked to 271.
RH-25 Troubleshooting - RF CCS Technical Documentation UHF Synthesizer The UHF VCO signal is used for RF channel selection. This signal is fed as a local signal for 1st mixer of RX path and for upconverter of TX path. When operating on lower band, the VCO signal is divided by 2 before feeding. This synthesizer is used for channel selection in all modes and both bands. The UHF synthesizer consists of an external 2GHz VCO module with loop filter components and integrated PLL parts in TACO.
