Nokia 2112, rh57 RF Description and Troubleshooting
Nokia Customer Care
2112 (RH-57) Series Transceivers
Troubleshooting - RF
Issue 1 07/2004 Company Confidential ©2004 Nokia Corporation
2112 (RH-57)
Troubleshooting - RF Nokia Customer Care
Contents Page
RF Troubleshooting......................................................................................................................................... 3
2112 General Troubleshooting Notes .................................................................................................... 3
Phone Components ..................................................................................................................................... 4
Phone Cannot Make a Call..................................................................................................................... 5
Transmitter Troubleshooting ....................................................................................................................6
Low Tx Power ............................................................................................................................................. 6
Cell Transmitter Setup............................................................................................................................. 7
Cell Transmitter Path ............................................................................................................................... 9
Cell Power Amplifier ............................................................................................................................. 13
Cell PMIC.................................................................................................................................................. 13
Cell IF/RF AGC and PA Control........................................................................................................... 15
Cell Power Detector .............................................................................................................................. 17
Tx System Block Diagram .................................................................................................................... 19
Receiver Troubleshooting ........................................................................................................................20
Rx IF........................................................................................................................................................... 20
Switching the Gain................................................................................................................................ 25
Rx RF.......................................................................................................................................................... 27
Rx AGC (Cell mode) ............................................................................................................................... 29
Receiver Block Diagram ....................................................................................................................... 31
Synthesizer Troubleshooting ..................................................................................................................32
Synthesizer Setup .................................................................................................................................. 32
VCTCXO Tuning....................................................................................................................................... 33
VCTCXO Reference Clock..................................................................................................................... 37
Synthesizer Block Diagram ................................................................................................................. 38
UHF Synthesizer ..................................................................................................................................... 39
Rx VHF....................................................................................................................................................... 40
Tx VHF ....................................................................................................................................................... 41
Tuning Descriptions ..................................................................................................................................43
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RF Troubleshooting
2112 General Troubleshooting Notes
First check the RX AGC PDM value when troubleshooting the receiver. The AGC value
should be close to the typical values in the tables. The Rx AGC tries to keep a constant
amplitude at the output of the receiver chain. If the AGC value indicates an AGC gain
that is substantially higher than normal, the AGC is compensating for extra loss in
another component. If the AGC PDM values are normal but there is still a problem, check
the actual AGC voltages. RF probing at specific locations in the chain can help to
pinpoint the source of the problem.
Likewise, first check the measured output power and AGC values when troubleshooting
the transmitter, which give an indication of where to start probing.
Although the tables in this chapter include power levels for many combinations of AGC
values, it is generally only necessary to check one combination. The additional
information is provided for use in unexpected situations. Likewise, although probing
points and signal-level information are given for each point in the receiver and
transmitter chains, it is not necessary to probe each point on every phone — only the
suspected trouble spots.
Absolute power measurements were made with an Agilent (HP) 85024A active
high-impedance probe. Other probes may be used (make sure the probe is highimpedance so the measurement does not load the circuit), but they may have different
gains. Therefore, adjust the absolute measurements accordingly, especially if you are
using a probe attenuator.
Typically, the higher loss occurs at the band edges where a range is given for loss.
Probing is not a very accurate method to measure absolute power; therefore, you cannot
expect measured results to exactly match the numbers listed.
Power depends on the impedance of the circuit. For example, if a filter has a nominal loss
of 5 dB, straightforward probing on the input and output and then subtracting might not
result in 5 dB because the input impedance could be different from the output
impedance. Most components in the RF section have the same input and output
impedance (50ohms). Where this is not the case, absolute power is noted in the tables in
dBm rather than loss or gain in dB.
Inject a CW tone into the receiver when testing the CDMA receiver. The gains and losses
are the same for a CW signal as for the CDMA.
Note: After opening the shield lids, always replace them with new lids.
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Troubleshooting - RF Nokia Customer Care
Phone Components
Figure 1 and Figure 2 illustrate the main components of the 2112.
RF connector LCD module connector
Figure 1: RF components (top)
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Nokia Customer Care Troubleshooting - RF
Cell Duplexer
Cell Isolator
PA PMIC DC-DC Converter
Cell Tx PA
Battery Converter
YODA Rx Downconverter
Rx IF CDMA Filter
UEM (B.B)
On/Off Switch
Rx IC “Alfred” LNA+Downconverter
Cell Rx RF SAW Filter
Cell Tx SAW Filter
Jedi Tx Up-Converter
VCO
VCTCXO
UPP (B.B)
SIM Card Connector
Phone Cannot Make a Call
Verify the following if the phone cannot make a call:
• The phone is in normal mode (i.e., the phone is searching for a signal, net server
is on).
• The Preferred Roaming List (PRL) is loaded into the phone.
Flash
Tomahawk Connector
Figure 2: RF components (bottom)
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• The phone is tuned and has passed tuning. (Read the tuning parameters using the
batch tune component in Phoenix; an untuned phone has all zeros in the tuning
file.)
• The call box channel is set for a channel in PRL.
• The SID is correct and entered into the phone.
• The MIN and MDN are entered into the phone.
• The VCTCXO is centered as described in the VCTCXO tuning description on
page 33.
• The transmitter and receiver are working properly in Local Mode.
Transmitter Troubleshooting
Low Tx Power
Use Phoenix to turn on the transmitter in Local Mode, and check the following:
• Verify the current (0.7 - 1A for max power, mode, and channel dependent).
• Use a microscope to visually inspect the PWB for proper placement, rotation, and
soldering of components.
• Look for the presence of a Tx signal on the spectrum analyzer at the correct
frequency:
• If the signal is not on frequency, check in the 100 MHz span.
• If the signal is present but off frequency, check the synthesizer. Most likely,
one of the synthesizers is not locked, or the VCO has no output signal.
• If the signal is not present, or is present but low in amplitude, use the
probing tables to determine where in the chain the fault occurs.
• Verify that the AGC PDMs are set for the desired Tx power as listed in the Tx AGC
Tuning table on page 12, and ensure that the AGC voltages are correct.
• Check the synthesizers for proper frequency and amplitude.
• Ensure that the power supplies to the transmitter have the correct voltage.
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Nokia Customer Care Troubleshooting - RF
Cell Transmitter Setup
Use the following steps to set up the phone for Tx troubleshooting in Phoenix.
1. Open the Phone Control dialog box.
Figure 3: Phone Control dialog box for Tx troubleshooting
2. Click the LOCAL button in the Phone State area to put the phone into Local
Mode.
3. Select the following values on the RF Main Mode dialog box:
• Band = Cell (CDMA)
• Channel = 384
• Mode = Rx/Tx
Figure 4: RF Main Mode dialog box for Tx troubleshooting
4. Click Set.
Note: Be sure that the “RF Main Mode set successfully...” message appears in the status bar.
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5. Select the Rho ON check box on the CDMA Control dialog box.
Figure 5: CDMA Control dialog box for Tx troubleshooting
6. Click Execute.
7. At this point you should be able to measure Tx Pout at the RF connector. The cell
band Tx Pout =0 to 2 dBm. If you do not see these values, set the AGC PDM for
25 dBm and probe the Tx path to figure out where in the path the fault occurs.
8. Open the General I/O dialog box to set the PA gain state.
9. Enter 10, 13, 12, and 8 in the PIN # fields.
Figure 6: General I/O dialog box for Tx troubleshooting
10. Select the boxes in the Enable column for each pin.
11. Cl i ck t h e Get All button.
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12. Ensure that all of the pins have a value of H in the State column. (Click the L
values to change them to H values.)
13. Adjust the following PDM field values on the RF PDM dialog box:
• Tx IF AGC = -280
• Tx RF AGC = -280
Figure 7: RF PDM dialog box for Tx troubleshooting
14. Ensure that the Phone Tx Pout = +25dBm and the current = 770-860mA.
Cell Transmitter Path
Table 1 indicates the test points (see Figure 8) to probe when troubleshooting the cell
transmitter path. It is recommended that you follow the steps in order. An HP high
frequency probe was used to make the frequency and output power measurements
Table 1: Cell Transmitter Test Points
Typical
Test
Point
Part* Function
Value/
Frequency
HP85024A
T1 Z601 pin1 Jedi-Out -43dBm/
836.52MHz
T2 Z601 pin 3 PA-In -25dBm/
836.52MHz
T3 N803 pin 8 PA-Out 5.0dBm/
836.52MHz
Typical
Value
Frequency
Prod Probe
-13.2dBm/
836.52MHz
-15.4dBm/
836.52MHz
18.3dBm/
836.52MHz
Comments
Output of Jedi Driver, Input to Tx
SAW Filter
Output of Tx SAW, Input to PA
Output of PA, Input to Isolator
T4 Z803T Iso-Out 2.2dBm/
836.52MHz
T5 C603L IF-Out -29dBm/
228.6MHz
10.3dBm/
836.52MHz
-24dBm/
228.6MHz
Output of Isolator, Input to
Duplexer
Tx IF Probing Point at IF Filter
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Table 1: Cell Transmitter Test Points (Continued)
Typical
Test
Point
Part* Function
Value/
Frequency
HP85024A
T6 C638T, C654T,
C633R,
C635R,
C603LR
T7 C655R VR7 2.7V dc UHF PLL Supply from UEM
T8 C636L, C624T,
L609B, C612L,
C630B, L607B
T9 C605R, C606R VAGC-Tx 0.2 to 1.8V dc Tx AGC Control Voltage from
T10 C658R, C600T VIO-Tx 1.8V dc Supply for Digital circuits from
T11 C805B, C810T,
C816R
VR5 2.7V dc VHF VCO/PLL, IQ modulator
VR2 2.7V dc Mixer, driver, and IF supply from
VBAT 3.6V dc Battery Voltage
Typical
Value
Frequency
Prod Probe
Comments
supply from UEM
UEM
UPP.
0.2V = Max Gain
1.8V = Min Gain
UEM
(Nominal Voltage 3.6V dc)
T12 C802L, C813L VPA 3.6V dc
(High Gain)
T13 C814R VG 1.8V dc
(Enable)
* The R, L, T, and B values at the end of the part names indicate the Right, Left, Top, and Bottom side
of the part respectively in Figure 8 and Figure 9.
Main PA Supply Voltage from
PMIC. Lgain=0.8V,
Mgain=-1.25V, Hgain=Vbat
PA Gate Voltage (Enable/Disable)
Disable=0V
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Figure 8 shows each test point for the Jedi TXIC section from Table 1, “Cell Transmitter
Test Points,” on page 9. Always attach a 20 dB pad (11881-60001) when probing with an
HP85024A high frequency probe.
Figure 8: (Top) PWB. (Bottom left) A zoomed view of the testing points on the Jedi TXIC section.
(Bottom right) A zoomed view of the Jedi TXIC section with part numbers.
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Figure 9 shows each testing point for the PA section from Table 1, “Cell Transmitter Test
Points,” on page 9. Always attach a 20 dB pad (11881-60001) when probing with an
HP85024A high frequency probe.
Figure 9: (Top) PWB. (Bottom left) A zoomed view of the testing points on the PA section.
Tx AGC Tuning
Tx power versus IF/RF PDM can be verified against FlaLi specification limits. Make sure
that the PA is set in high gain mode (GenIO bits 10, 13, and 12 are set to H).
(Bottom right) A zoomed view of the PA section with part numbers.
Table 2: Tx AGC Tuning Steps
Tx Tuning
AGC Step
Tx AGC (0) 308 -46 -55 -37
Tx AGC (1) 130 -24 -34 -14
Tx AGC (2) 85 -15 -25 -6
Tx AGC (3) 51 -4.5 -14 5
Tx AGC (4) 19 2.5 -7 12
Tx AGC (5) -5 6 -3 15
Tx AGC
PDM Value
Target
Power
Low
Limit
High
Limit
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Table 2: Tx AGC Tuning Steps (Continued)
*Not an actual FlaLi tuning PDM. The PDM produces approximately 25dBm at the antenna
connector.
Cell Power Amplifier
The power amplifier (PA) has the DC/DC converter (PMIC device), which controls the
transmitter. The following tables show the circuits that have an effect on the transmitter
path and how to troubleshoot them.
Tx Tuning
AGC Step
Tx AGC (6) -94 15 6 24
Tx AGC (7)* -280* 25 21 27
Tx AGC
PDM Value
Table 3: PA Power and Gain Measurements
Power Amp
Input Test Point
pin3-Z601 left-R814
Table 4: PA Power and Gain Specifications
Target
Power
Low
Limit
Power Amp
Output Test Point
High
Limit
Mode Name
Gain mode 0 V0 up to 6 23.8 0.75- 0.88 C806
Gain mode 1 V1 6 to 11 25.2 1.125- 1.375 C806
Gain mode 3 V2 Not used Not used 2 - 2.5 C806
Gain mode 2 Bypass 11 up 29 3 - 4 C806
Gain mode 0 V0 up to 6 23.8 0.75- 0.88 C806
Gain mode 1 V1 6 to 11 25.2 1.125- 1.375 C806
*Not an actual FlaLi tuning PDM. PDM to produce approximately 25dBm at antenna connector.
Power Output
Range
Nominal Gain Vcc Range Vcc Test Point
Cell PMIC
The following tables show the PMIC troubleshooting information.
Table 5: PMIC Setup
Mode Tx Rx Band
Local On On CELL
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Table 6: PMIC Measurements
Pin Label Test Point Units Depends On Comments
1 EP Pin 1 1.8 UPP IC enable = GenIO 10
2 M0 Pin 2 1.8 UPP Control 0 = GenIO 12
3 M1 Pin 3 1.8 UPP Control 1 = GenIO 13
4NC NC NC NC NC
5 FB Pin 5 0.75 - 4 M0, M1 See PA worksheet. Output to flyback
inductor.
6 FB Pin 6 0.75 - 4 M0, M1 Shares PWB pad with pin 5
7 BYPVout bottom-
C808
8 VDD right-L810 VBATT VBATT Digital DC supply, shared with pin 12,
9 VSS GND GND GND Digital GND, shared gnd with pin 13
10 NC NC NC NC NC
11 Vbgap NC NC NC Bandgap voltage output
12 VDD right-L810 VBATT VBATT Digital DC supply
13 Vss GND GND GND Digital GND, shared gnd with pin 9
14 Vsw right-L810 VBATT VBATT Switcher supply
15 Vsw right-L810 VBATT VBATT Switcher supply
16 Gsw GND GND GND Switcher GND, does not share with pin 9
0.75 - 4 M0, M1 PMIC bypass output used at
Pout > 12 dBm
14, and 15
and pin 13
Table 7: Good Phone PMIC Resistances
Pin Resistance
160k
275k
380k
41.59M
51.6M
62M
72M
82M
90.1
10 100
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