Nokia 8270 Service Manual 10 nsd5trouble
Programmes After Market Services
NSD-5 Series Transceivers
10. Troubleshooting
Issue 1 05/02 Nokia Corporation
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10. Troubleshooting P AMS Technical Documentation
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Contents
Page No
Troubleshooting............................................................................................................. 5
Baseband Troubleshooting............................................................................................. 5
Main Circuit Sections..................................................................................................... 5
Power Circuitry ............................................................................................................5
CCONT ........................................................................................................................5
Vbat ..............................................................................................................................5
Vref ..............................................................................................................................5
Linear Regulators .........................................................................................................5
1. Vbb........................................................................................................................ 5
2. RF Regulators (VR1–VR7)................................................................................... 6
3. V2V (VMAD) ....................................................................................................... 6
Switch mode regulator .................................................................................................6
1. V5V (+5V_POWER) ............................................................................................ 6
2. VSIM (3V_5V) ..................................................................................................... 6
A/D Conversion......................................................................................................... 6
Watchdog .................................................................................................................. 7
Serial bus................................................................................................................... 7
Clocks ..........................................................................................................................7
Sleep Clock ............................................................................................................... 7
System Clock............................................................................................................. 7
CDMA clock............................................................................................................. 7
Charging Circuit ..........................................................................................................7
CAFE ...........................................................................................................................8
Microphones.............................................................................................................. 8
Earpiece and XEAR .................................................................................................. 8
Transmit and Receive RF Signals............................................................................. 8
MAD4 ..........................................................................................................................8
DSP............................................................................................................................ 8
MCU.......................................................................................................................... 9
Memories .....................................................................................................................9
Troubleshooting Instructions ....................................................................................... 10
Check System Clock ............................................................................................... 11
Check Sleep Clock.................................................................................................. 12
In the Field .............................................................................................................. 12
Power Supplies........................................................................................................ 12
Phone is Totally Dead ................................................................................................13
Phone Won’t Power Up .............................................................................................13
Power Doesn’t Stay on or Phone is Jammed .............................................................14
Flash Programming Fails ...........................................................................................14
Audio failures ............................................................................................................14
Battery Will Not Charge ............................................................................................18
Baseband Test Points .................................................................................................19
Baseband Test Point Layout (Top side view) ............................................................21
Baseband Test Points Layout (Bottom side View A) ................................................22
Baseband Test Points Layout (Bottom side View B) ................................................23
RF Troubleshooting ..................................................................................................... 24
Purpose ......................................................................................................................24
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Introduction ................................................................................................................24
Reference Documents ................................................................................................24
WinTesla General Set Up ............................................................................................ 25
CDMA Fault-finding Set Up .....................................................................................25
Synthesizer Tuning Menu ..........................................................................................26
Tuning AFC............................................................................................................. 26
Description of Test.................................................................................................. 26
Definition of Result................................................................................................. 27
Manual Verification ................................................................................................ 27
Synthesizer Troubleshooting .....................................................................................27
Test Points............................................................................................................... 29
Trouble Case 1: Tx VHF LO Power < -20dBm ........................................................29
Trouble Case 2: Rx VHF LO Power < -12dBm ........................................................30
Trouble Case 3: UHF LO Power < -5dBm ................................................................30
Trouble Case 3: Rx UHF LO Power < -5dBm ..........................................................30
TX Tuning .................................................................................................................35
Description of Test.................................................................................................. 35
Definition of Result................................................................................................. 36
Manual Verification ................................................................................................ 36
TX Troubleshooting Flowchart .................................................................................38
1900 PCS Tuning Rx IF AGC ...................................................................................40
Description of Test.................................................................................................. 40
Definition of Result................................................................................................. 41
Manual Verification ................................................................................................ 41
1900 PCS Tuning Rx IF Compensation ....................................................................42
Description of Test.................................................................................................. 42
Definition of Result................................................................................................. 42
Manual Verification ................................................................................................ 43
RX Troubleshooting ..................................................................................................45
Troubleshooting ...................................................................................................... 45
Rx VHF LO Measured at RIF Pin 20 with a Hi Z Probe........................................ 46
RX Troubleshooting Flowchart .................................................................................46
Test Points .................................................................................................................46
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Troubleshooting
Baseband Troubleshooting
Each main portion of the circuit will be described in enough detail for the troubleshooter
to determine whether or not that part of the circuit being evaluated is functional. It will
be helpful to use the placement diagram, which illustrates all of the necessary testpoints
in the baseband circuit, to troubleshoot the phone. The placement diagram is intended to
be used concurrently with this document. Herein, TPD refers to Test Point Designation.
Main Circuit Sections
Power Circuitry
There are two ASICs in the baseband section, which supply power to most of the phone.
CCONT is the main power management ASIC. Two discrete linear regulators are used as
well.
CCONT
Vbat
Vref
CCONT is the main power management ASIC. Its features include eight 2.8V linear regulators, a linear regulator with adjustable output, a reference voltage output, a 5V switch
mode regulator, an 8-channel A/D converter, and 32kHz clock circuitry. Each of the main
functions and signals is described below, including information on how to verify correct
operation.
CCONT is powered directly from the battery voltage (Vbat). Since CCONT is a uBGA, the
physical connection of CCONT’s power pins cannot be verified. Vbat must be checked
instead at the closest external component, which is shown as TPD. Valid voltages are
3.2 – 4.2V and should always be powered, assuming voltage is applied to the
battery terminals.
Vref is used as a reference voltage both internal and external to CCONT. It is switchable
between the nominal voltages of 1.500V and 1.251V, with the default at power-up being
1.500V. The phone uses the 1.251V reference, so once flash software is running, Vref
should switch to 1.251V.
Check Vref at TPD. Valid voltages are 1.478 – 1.523V and 1.244 – 1.258V, respectively.
Linear Regulators
1. Vbb
Vbb supplies power to most of the baseband circuitry. This regulator should be on at all
times during CCONT’s power on, reset, and sleep modes. Nominal voltage is 2.8V, but
anything in the range 2.7 – 2.87V is valid. Vbb is found at TPD30.
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2. RF Regulators (VR1–VR7)
VR1 through VR6 are referred to as the RF regulators. Most are switchable, and all should
be within 2.67 – 2.85V when they are on (2.8V nominal). VR1 and VR6 are always on during CCONT’s power on mode. The rest of the regulators are switchable and are normally
on during one or more of the various phone states, but may be turned on at any time
with the service software in order to verify their output. The RF regulators can be
checked at the following test points.
a) VR1 – TPD
b) VR1_SW – TPD
c) VR2 – TPD
d) VR3 – TPD
e) VR4 – TPD
f) VR5 – TPD
g) VR6 – TPD
h) VR7 - TPD
3. V2V (VMAD)
The V2V (VMAD) regulator is intended to power the MAD4 ASIC core. The output is
adjustable from 1.3V to 2.65V in 0.225V steps, and is used with MAD4 ver 3 (but not
MAD4 ver 2). The output at V2V, when MAD4 ver 3 is mounted, should be 1.750V ±5%
and can be checked at TPD27.
Switch mode regulator
1. V5V (+5V_POWER)
V5V is a 5V switch mode regulator, which always remains on during CCONT power on
mode. Valid voltages are 4.8V to 5.2V, and it can be checked at TPD2.
2. VSIM (3V_5V)
VSIM is powered by the same switch mode regulator as V5V; however, it is switchable
between 3V and 5V. The phone uses VSIM as the 3V FLASH programming voltage, so it
should remain off unless the phone is being flashed. Valid voltages are 2.8V to 3.2V, and
it can be checked at TPD1.
A/D Conversion
CCONT contains a 10–bit A/D converter that is multiplexed between eight different
inputs. They are used mainly for battery and charger monitoring. The eight inputs are:
Vbat (battery voltage), ICHAR (charger current), VCHAR (charger voltage), BSI (battery
type), BTEMP (battery temperature), VCXOTEMP (PA temperature), and EAD (accessory
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detection). These readings can be accessed through the service software. Check for
shorts or opens on the resistor networks connected to these signals if the flash align test
software reports that they are out of range.
Watchdog
CCONT’s watchdog circuitry consists of an 8-bit down counter that causes CCONT to
power down when zero is reached. The counter may be reset by loading a new, non–zero
value into the watchdog register via CCONT’s serial bus. It is difficult to verify the watchdog function, but the serial bus may be verified.
There is a watchdog disable pin, which allows the watchdog timer to expire without
shutting down the phone. This pin is mainly used as one of the methods to turn on
CCONT from power off mode. While the phone’s power key is pressed, this pin should be
pulled low and can be checked at TPD 26 using a 70k resister. The watchdog can be disabled by pulling down the above-mentioned pin (WD_DIS) by shorting TPD 26 and
ground.
Serial bus
Since the serial bus is used to control almost all of CCONT’s functions, any shorts or open
circuits on these three lines would cause CCONT to be completely nonfunctional. The
main symptoms are the following:
CCONT will turn on when the power key is pressed (verify this by checking Vbb), but will
then power off after 32 seconds. All three serial bus signals (CCONTCSX,
UIF_CCONT_SDIO, and UIF_CCONT_SCLK) should toggle when attempting to write to a
CCONT register.
Note: If the LCD does not come on during this time, it may indicate that the serial bus is functional,
but the phone does not have valid flash code.
Clocks
Sleep Clock
The 32kHz sleep clock is generated by CCONT, and can be checked at TPD32. The 32kHz
square wave will be present only after the phone is turned on.
System Clock
The 19.2MHz system clock is generated by the VCTXO in the RF section, and then squared
in CAFE. Check TPD11, which should be a 2.8V squarewave. This clock is not active during
the phone’s sleep mode (CLK_EN is low during sleep mode).
CDMA Clock
The CDMA clock is 9.8MHz and is generated in CAFE with a PLL. This should be a 2.8V
squarewave and can be verified at TPD10.
Charging Circuit
The charging switch, CHAPS, is controlled by a PWM from CCONT. This PWM can be at
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1Hz or at 32Hz, with varying duty cycles, and should only be active when a charger is
detected. The frequency depends on charger type. To verify correct operation of CHAPS,
monitor the charging current (ICHAR) with the service software. When the PWM is off,
current should be approximately 200uA. When the PWM is on, it must be greater than
approximately 300mA.
CAFE
The CAFE ASIC performs various functions with respect to the RF circuitry and audio. It
digitizes the analog voice signals from the microphone as well as converts received digital data to voice signals to be sent to the earpiece. This also includes accessory microphones and speakers. It also generates and decodes I and Q data for CDMA signals. CAFE
also acts as a clock squaring circuit and CDMA clock generator.
Microphones
The internal microphone is biased using transistor V280, which is powered by VR1_SW.
MICP should be about 1.7VDC, and MICN should be about 0.4VDC. Internal microphone
bias should only be active during a call. The XMIC is biased by the AUXOUT signal
through R240 and R241. The AUXOUT output provides 1.5V bias voltage to the external
microphone.
Earpiece and XEAR
The internal earpiece is driven differentially (EARP and EARN). The DC voltage on these
two pins is 1.35V. The difference in the DC voltage between these two pins should not be
more than 50mV.
The XEAR signal drives audio to the external accessories. The CAFE signal name is HF. The
DC level on this pin should be 1.35V. HFCM should also be at 1.35V. The difference in DC
voltage between these two pins should not be more than 50mV.
Note that SGND is the return path for XMIC and XEAR.
Transmit and Receive RF Signals
In CDMA mode, receive I and Q channel RF signals [RXIQ(3:0)] come into CAFÉ pins.
C201, C202, C203, and C204 can also be checked for these signals since they are in series
with the CAFÉ pins. Transmit I and Q RF signals [TXIQ(3:0)] can be seen at C205, C206,
C207, and C208.
MAD4
The MAD4 ASIC is the core of the baseband functionality and basically contains the DSP,
MCU, and CDMA logic. The DSP is used to perform functions such as RF control, DTMF
tone generation, and implementation of the vocoder. The MCU is used to perform functions that do not require as much power — higher-level functions such as UI software
(key presses, backlighting, LCD functions, etc.) and mode control.
DSP
The DSP sends control signals to the RF via PDMs. In order to control RF parameters such
as TX_LIM_ADJ, a continuously variable analog signal must be used. Since the DSP out-
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puts only digital signals, a PDM RC circuit is used to convert the digital output signal to
an average analog voltage. A PDM line will always have a series resistor followed by a
shunt capacitor. The output of the MAD4 PDM lines will appear as squarewave signals.
However, after the shunt capacitor, the signals will appear to be DC with perhaps a slight
ripple. The RC circuit acts as an integrator in order to yield the average value (DC) of the
squarewave signal.
The transmit data bus (TXD(7:0)) is 8 bits wide. In CDMA mode, this bus is multiplexed
between sending I and Q data. The signals required to transfer TX data are
CAFE_TX_GATE, CLK9M80, and IQSEL. CAFE_TX_GATE must be high to transfer data, and
the data is clocked by CLK9M80, which is running at 9.8MHz.
MCU
The MCU is used to perform functions that require less processing power than the DSP. It
runs UI software and mode control; interfaces to MBUS; downloads code to flash; reads
and writes the EEPROM; controls charging; and interprets A/D data from CCONT.
Memories
MAD4 interfaces to three memories — Flash, SRAM, and EEPROM. All of them are powered by 2.8V (Vbb). During Flash programming, Vpp (signal name is Vff_flash on schematic) is driven to Flash memory.
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Troubleshooting Instructions
The first thing to do is to carry out a thorough visual check of the module. Make sure
that there is no mechanical damage and that solder joints are okay. Most failures will be
the result of SMD errors. Common errors include: solder placed where it shouldn’t be,
parts sliding off their pads, or parts placed incorrectly. A good visual inspection will pinpoint a large percentage of failing phones.
Before changing anything, also check all supply voltages and the system clock/sleep
clock.
The Troubleshooting Instructions section contains five modules:
- How to check/fix the system/sleep clock
- How to check/fix the power supplies
- How to check/fix the flashing faults
- How to check/fix the audio faults
- How to check/fix the charger faults
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Check System Clock
Figure 1: System clock picture
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Check Sleep Clock
Figure 2: Sleep clock picture
In the Field
Although solder joints may be adequate to pass manufacturing requirements, they may
not withstand mechanical stress or heat cycling. Cracked or broken solder may cause
failures to occur as the result of simple use. Reflowing some of the major components
may fix problems where the phone exhibits strange behavior (some buttons may not
work, the phone doesn’t ring, or the phone doesn’t power on).
Power Supplies
Measure the power supplies. Test points are illustrated in the baseband test points table
and the layout diagram.
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Power up sequence test:
CCONT digital parts keep MAD4 in reset by keeping PURX down for a delay of 62ms.
Here is the start-up sequence picture:
Ch1 = PWRONX
Ch2 = SLEEPCLK
Ch3 = PURX
Ch4 = RESETX
Phone is Totally Dead
The phone doesn’t take current at all when the power switch is pressed or when the
watchdog disable pin (TPD331) is grounded.
Make sure that the battery voltage you use is within specification (i.e., 3.2 - 4.2V). If the
voltage is lower than that, CCONT hardware (N302) prevents power on.
If the battery voltage is within the specification, change the CCONT (N302).
High current: This indicates that the problem is likely the result of a shorted component.
Check the orientation of major components (including RF) and check for shorts. Likely
components are those that are powered directly from Vbat such as CCONT, the PAs, and
various capacitors.
Low current: This indicates that CCONT is now powering on. Verify CCONT circuitry.
Phone Won’t Power Up
Do a visual inspection. Verify that all parts are on the board correctly, and that none is
missing. Phone won’t power up often is related to VCTCXO solder joints cracking and no
19.2MHz to the BB.
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Check that the 32kHz clock turns on when attempting to power up.
Check the power circuitry. This includes Vbat, Vref, and all of the linear regulators.
Power Doesn’t Stay on or Phone is Jammed
If this type of fault occurs after flash programming, there are most likely open joints in
ICs. Solder the IC joints. Normally, the power will be switched off by CCONT(N302) after
30 seconds if the CCONT watchdog cannot be served by software. This updating can be
seen with an oscilloscope at CCONTCSX(TPD334). In normal cases, there is a short pulse
from “1” to “0” every 8 seconds.
Because of underfill, check the supply voltages, clock signals, and power sequence. If the
power sequence fails, there are some open connections under MAD4 or compomemory. If
everything appears to be correct, it is best to erase the flash memory and try to reput the
software to the phone again.
Flash Programming Fails
The flash programming can be done via flash connector X052 or via dedicated PCB pads
(J56,J57). In production, the first programming is done via flash connector. After this, the
flash connector is cut away; as a result, the programming must be done via PCB pads visible through the shield under the battery. The fault-finding diagrams for flash programming are shown in the start-up sequence diagram.
In the case of flash programming errors, the flash prommer may provide some information about a fault. The fault information messages could be:
- MCU doesn’t boot
- Serial clock line failure
- Serial data line failure
- External RAM fault
- Algorithm file or alias ID not found
- MCU flash Vpp error
Flash: Failure to flash is the main baseband failure. Check all the CCONT regulators,
especially Vbb, VR1, and VR6 for shorts. Check clocks and reset circuitry. Check for shorts
on the address, data, and chip enable lines on the memories and MAD4. If a short is
detected, it may be that it is beneath the BGA flash and may have to be replaced.
Note: Unfortunately there is no ROM software that can be run when the phone does not
flash. Typically, this software would be used to test all of the interfaces between MAD4
and its peripherals. Therefore, it must be visually (or by ohmeter) determined whether
there is a possible short between two or more of the address or data lines.
Audio failures
If audio fails to be heard from the earpiece (or XEAR), check the following:
Check earpiece contacts.
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Verify that the CAFÉ EARP and EARN bias is on. If necessary, check the entire receive
path—Rx voice data comes from the RF through the RXIQ bus (CDMA), then to MAD4
through RXD (11:0) (Refer to schematic).
The Rx voice data then goes back to CAFE on CAFESIO (0), and then to the earpiece or
XEAR. CAFESIO (2) must also be active.
Conversely, if the transmit audio is not working, the fault could be anywhere in the
transmit path. Check the following:
Check microphone contacts.
Microphone bias.
Tx voice data is transferred from CAFÉ to MAD4 on CAFESIO (1). CAFE-SIO (2) must also
be active. Tx voice data is then sent back to CAFÉ on the TXD bus (See schematic).
Tx voice data is then sent to RF on the TXIQ bus.
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