The following hints should help to find the cause of the problem when the circuitry
seems to be faulty. This trouble shooting instruction is divided into sections.
1Phone is totally dead
2Power does not stay on or the phone is jammed
3Flash programming does not work
4Display is not working
5Plug in SIM card is out of order (insert SIM card).
6Audio fault
7Charging fault
The first thing to do is carry out a through visual check of the module. Ensure in particular that:
a) there are no mechanical damages
b) soldered joints are OK.
General instructions
Most semiconductors are static discharge sensitive! ESD protection must be taken care
of during repair (ground straps and ESD soldering irons). Mjoelner, PA, UEM, UPP, and
Flash are moisture sensitive and must be pre-baked prior to soldering, if they have been
out of their vacuum package longer than the specified time.
•Connect test jig (MJS-37) to computer with DAU-9S cable or to FPS-8 Flash
Prommer with AXS-4 serial cable.
•Make sure that you have PKD-1 dongle connected to computer’s parallel port.
•Connect DC power supply to module test jig (MJS-37) with FLC-2 cable.
•Set the MJS-37 supply voltage to 8-12VDC. If the input-voltage exceeds 12VDC,
the MJS-37 jig may be damaged.
Note: By default the MJS-37 supplies the phone with 4.1VDC. If other output voltages is
needed, it is possible to modify MJS-37 to support this by removing R110 and mount S104.
See MJS-37 schematic for more info.
•When doing BB energy management (EM) calibrations use JBV-1 jig and DC supply voltage 12 – 15 V.
• JBV-1’s current consumption is ~ 40 mA with 3.9 V supply voltage and ~ 80
•Set the phone module to test jig (MJS-37) and start Phoenix service software.
Initialize connection to phone (use FBUS driver when using DAU-9S and COMBOX driver when using FPS-8).
The flash programming can only be done via the pads on the PWB (J100).
In case of Flash failure in FLALI station, problem is most likely related to SMD problems.
Possible failures could be short-circuit of balls under µBGAs (UEM, UPP, FLASH). Missing
or misaligned components.
In flash programming error cases the flash prommer can give some information about a
fault.
The fault information messages could be:
- Phone doesn't set FBUS_TX line low
Because of the use of uBGA components it is not possible to verify if there is a short circuit in control- and address lines of MCU (UPP) and memory (flash).
If this kind of failure is presenting itself immediately after FLALI, it is most likely caused
by ASICs missing contact with PWB.
If for some reason the MCU does not service the watchdog register within the UEM, the
operations watchdog will run out after approximately 32 seconds. Unfortunately, the
service routine can not be measured.
This error can only happen at power up where several self-tests is run. If any of these test
cases fails the display will show the message: "Contact Service".
It's individual test cases so the below lineup of error hunting's has no chronological
order. Use common sense and experience to decide which test case to start error hunting
at.
Phone does not register onto the network, or the phone cannot make a call
If the phone doesn't register to the network, the fault can be in either BB or RF. Only few
signals can be tested since several signals is 'burried' in one or more of the inner layers of
the PWB.
First of all check that SIM LOCK is not causing the error by using a Test-SIM card and
connect the phone to a tester.
The hardware of the SIM interface from UEM (D200) to the SIM connector (X387) can be
tested without a SIM card. When the power is switched on the phone first check for a
1,8V SIM card and then a 3V SIM card. The phone will try this four times, whereafter it
will display ”Insert SIM card”.
Display shows :
"Insert SIM Card"
Yes
Check for SIM voltage during power-up
Ch1 : VSIM
Ch2 : RESET
X387
Verify that phone checks for
1,8V-SIM, and then 3V-SIM
The error ”SIM card rejected” means that the ATR message received from SIM card is corrupted, e.g. data signal levels are wrong. The first data is always ATR and it is sent from
card to phone.
Display shows :
"SIM Card Rejected"
Yes
VSIM = min. 1,6V(1,8V Card)
X387
VSIM = min. 2,8V(3V Card)
(See illustration below)
Yes
X387
ATR data can be seen at
SIM data pin.
Yes
SIM Interface OK
No
No
Check :
R386, PWB.
Else defective D200*
Check :
X387, R386, PWB.
For reference a picture with normal SIM power-up is shown below.
Two types of measurements are used in the following. It will be specified if the measurement type is "RF" or "LF".
•RF measurements should be done with a Spectrum Analyser and a high-frequency 500 ohm passive probe, for example HP54006A. (Note that when measuring with the 500 ohm probe the signal will be around 20 dB attenuated. The
values in the following will have these 20 dB subtracted and represent the real
value seen on the spectrum analyser).
Note that the testjig have some losses which must be taken into consideration when
calibrating the test system.
•LF (Low frequency) and DC measurements should be done with a 10:1 probe and
an oscilloscope. The probe used in the following is 10MW/8pF passive probe. If
using another probe then bear in mind that the voltages displayed may be
slightly different.
Always make sure the measurement set-up is calibrated when measuring RF parameters
on the antenna pad. Remember to include the loss in the module repair jig when
realigning the phone.
Most RF semiconductors are static discharge sensitive. So ESD protection must be
taken during repair (ground straps and ESD soldering irons). Mjoelner and Bifrost is moisture sensitive so parts must be pre-baked prior to soldering.
Apart from key-components described in this document there are a lot of discrete components (resistors, inductors and capacitors) for which troubleshooting is done by checking if soldering of the component is done properly and checking if the component is
missing from PWB. Capacitors can be checked for short-circuiting and resistors for value
by means of an ohmmeter, but be aware in-circuit measurements should be evaluated
carefully.
In the following both the name EGSM and GSM900 will be used for the lower band and
both PCN and GSM1800 will be used for the upper band.
General description of the RF circuits
In the following general descriptions different colours are used in the block diagram. The
GSM 900 signal route is shown in red, the GSM1800 route in green and the common signal lines are shown in blue. Signal lines which is common for both
Receiver signal path
The signal from the antenna pad is routed to the RX/TX switch ( Z700). If no control voltage is present at VANT2 and VANT1 the switch works as a diplexer and the GSM900 signal is passed through the RX/TX switch to GSM-RX and the GSM1800 signal is passed to
DCS-RX.
From the RX/TX switch the GSM900 signal is routed to the SAW filter (Z602). The purpose of the SAW filter is to provide out-of band blocking immunity and to provide the
LNA in Mjoelner (N600) with a balanced signal. The front end of Mjoelner is divided into
a LNA and Pre-Gain amplifier before the mixers.
DCN2
DCN2
VRX
VR6
RXIP
RXIM
RXQP
RXQM
The output from the mixer is feed to Baseband part of Mjoelner where the signals amplified in the BBAMP and low pass filtered in LPF1 before the DC compensation circuits in
DCN1. The DCN1 output is followed by a controlled attenuator and a second lowpass filter LPF2. The output from LPF2 is DC centered in DCN2 before being feed to the BB for
demodulation.
The GSM1800 signal chain is similar to GSM900, the SAW filter numbered Z601.
Transmitter signal path
The I/Q signal from the BB is routed two the modulators for both 900 and 1800 MHz. The
output of the modulators is either terminated in a SAW filter ( Z603 ) for GSM 900 or a
balun for GSM1800. Both signals are amplified in buffers whereby a limiting effect takes
place to suppress some of the AM contents of the signal. The amplitude limited signal is
then amplified in the PA (N700) where the gain control takes place. In order to control
the TX level a sample of the signal is taken in a directional coupler ( L709 for GSM900
and L704 for GSM1800) and used in the power loop amplifier in Mjoelner to establish
the right output power. The TX signal from the couplers is feed to the RX/TX switch, used
to select which signal to route to the antenna.
The PLL supplies Local Oscillator (LO) signals for the RX and TX-mixers. In order to be able
to generate LO-frequencies for the required EGSM and PCN channels a regular synthesiser-circuit is used. All blocks for the PLL except for the VCO, reference X-tal and loopfilter is located in the Mjoelner IC.
The reference frequency is generated by a 26MHz Voltage Controlled X-tal Oscillator
(VCXO) which is located in the Mjoelner IC. Only the X-tal is external. 26MHz is supplied
to BB where a divide-by-2 circuit (located in the UPP IC) generates the BB-clock at
13MHz. The reference frequency is supplied to the reference divider (RDIV) where the
frequency is divided by 65. The output of RDIV (400kHz) is used as reference clock for the
Phase Detector (ϕ).
The PLL is a feedback control system controlling the phase and frequency of the LO-signal. Building blocks for the PLL are: Phase detector, Charge Pump, Voltage Controlled
Oscillator (VCO), N-Divider and loopfilter. As mentioned earlier only the VCO and loopfilter is external to the Mjoelner IC.
The VCO (G600) is the component that actually generates the LO-frequency. Based on
the control voltage input the VCO generates a single-ended RF output. The signal is then
differentiated through a balun. This signal is fed to the Prescaler and N-divider in Mjoelner, these 2 block will together divide the frequency by a ratio based on the selected
channel. The divider output is supplied to the phase detector which compares the frequency and phase to the 400kHz reference clock. Based on this comparison the phase
detector controls the charge pump to either charge or discharge the capacitors in the
loopfilter. By charging/discharging the loopfilter the control voltage to the VCO changes
and the LO-frequency will change. Therefore the PLL will make the LO-frequency stay
locked to the 26MHz VCXO frequency.
The loopfilter consists of the following components: C639-C641 and R618-R619.
The PLL is operating at twice the channel center frequency when transmitting or receiving in the PCN band. For the EGSM band the PLL is operating at 4-times the channel frequency. Therefore divide-by-2 and divide-by-4 circuits are inserted between the PLL
output and LO-inputs to the PCN and EGSM mixers.
Table 1: Frequency plan
Frequency bandChannelSystem Frequency Band (MHz)PLL Frequency band (MHz)
EGSMRX975-1023
TX880.2 – 914.83520.8 – 3659.2
1 - 12
925.2 - 959.83700.8 - 3839.2
PCNRX512 – 8851805.2 – 1879.83610.4 – 3759.6
TX1710.2 – 1784.83420.4 – 3569.6
According to the table above the PLL must be able to cover the frequency range
All power supplies for the RF Unit are generated in the UEM IC (D200). All power outputs
from this IC has a decoupling capacitor at which the supply voltage can be checked.
The power supply configuration used in the HDb12 phone is shown in the blockdiagram
below:
The names in bold are signal names used on the RF schematic pages. Names in the boxes
within the Mjoelner and the VCO refers to pin names on the respective ICs (N600, G600).
Table 3:
Supply name RFSupply name UEMMinTypMaxUnit
VTXVR22.642.782.86V
VXOVR32.642.782.86V
VCPVR1A4.75V
VPLLVR52.642.782.86V
VRXVR62.642.782.86V
VVCOVR72.642.782.86V
VBBVIO1.721.81.88V
VREF2VrefRF011.3341.351.366V
VBATTBATTERY3.13.65.2V
Please see the picture below for measuring points at the UEM (D200).
Figure 16 : TX measurement point in Mjolner (N600) shielding can
TXQI
Bal_Input1
Bal_Input1
Bal_Input2
GSM
Bal_Input2
GSM
OUT_D_T
OUT_G_TX
TXIP
TXIM
General instructions for GSM TX troubleshooting
Apply a RF-cable to the RF-connector to allow the transmitted signal act as normal. RFcable should be connected to measurement equipment or to at least a 10-dB attenuator,
otherwise the PA may be damaged.
Start Phoenix-Service-Software and establish a connection to the phone e.g. FBUS.
Select File and Product: Gemini
Select: Maintenance, Testing and RF Controls
Band:GSM 900
Active Unit:TX
Tx Power Level:5
Tx Data Type:Random
Measure the output power of the phone; it should be around 32.5 dBm. Remember the
loss in the jig; around 0.3 dB.
Fault finding chart for GSM900 transmitter
Fault finding in output power
For the spectrum analyser measurements in the following chart use the 500 ohm passive
probe. Since the signal measured is bursted it is advised to set the analyser to maxhold.
I/Q signals look almost the same regardless if modulation is by "1" or by "0". There is no
significante difference between TXIP and TXIM. The same is valid for TXQP and TXQM.
PCN TransmitterGeneral instructions for PCN TX troubleshooting
Apply a RF-cable to the RF-connector to allow the transmitted signal act as normal. RFcable should be connected to measurement equipment or to at least a 10-dB attenuator,
otherwise the PA may be damaged.
Start Phoenix-Service-Software and establish a connection to the phone e.g. FBUS.
Select File. Choose Product: Gemini
Select: Maintenance, Testing and then RF Controls.
Band:GSM 1800
Active Unit:TX
Tx Power Level:0
Tx Data Type:Random
Your screen should look like:
Measure the output power of the phone; it should be around 28.5 dBm. Remember the
loss in the jig; around 0.7 dB.
There is only one PLL synthesizer generating Local Oscillator frequencies for both RX and
TX in both bands ( PCN and EGSM). The VCO frequency is divided by 2 for PCN operation
or by 4 for EGSM operation inside the Mjoelner IC.
General instructions for Synthesizer troubleshooting
Start the Phoenix-Service-Software and
Select: Product: NHM-8NX
Select: Maintenance, Testing and then RF Controls.
Band GSM1800
Active UnitRX
Operation ModeContinuous
RX/TX Channel700
It is not possible to measure the output of the VCO (G600) directly as this component is
placed underneath a shielding can without detachable lid. However with spectrum analyzer and 500 ohm passive probe it is possible to get an indication if the VCO outputs the
correct frequency. To do this probe R656 – the frequency should be 3685.6MHz and the
power should be around –50 dBm.
26 MHz Reference Oscillator ( VCXO )
The 26 MHz oscillator is located in the Mjoelner IC (N600). The coarse frequency for this
oscillator is set by an external crystal (B600). The reference oscillator is used as a reference frequency for the PLL synthesizer and as the system clock for BaseBand. The
26MHz signal is divided by 2 to achieve 13MHz inside the UPP IC (D400). The 26 MHz
signal from the VCXO can be measured by probing R425 (must be measured on the UPP
side of R425 i.e. the end not connected to C425). The level at this point is approx.
700mVpp. Frequency of this oscillator is adjusted by changing the AFC-register inside the
Mjoelner IC. This is done via the Mjoelner serial interface.
The VCO is generating frequencies in the range of 3420.2MHz – 3839.2 MHz when the
PLL is running. The output frequency from the VCO is led to the Local oscillator input of
the Mjoelner IC (N600), where the frequency is divided by 2 or 4 so that they can generate all channels in EGSM and PCN respectively. Frequency of the VCO is controlled by a
DC-voltage ( Vctrl ) coming from the loopfilter. The loopfilter consists of the components
R618, R619 and C639-C641. Range of the Vctrl when the PLL is running (locked) is 0.7V
– 3.8V. Even if the PLL is not in locked state (Vctrl out of range) there is some frequency
at the output of the VCO (G600) which is between 3 and 4 GHz. This is of course only
true if the VCO is working and if the VCO power supply is present (2.7V).
If the phone stops working a short time after the power is turned ON, a possible reason
forthis might be that the 26MHz system clock signal is not getting to the UPP clockinput in BaseBand. In this case check the following:
1Turn on the phone and check
2VCXO Power supply (C620) = 2.7V
3VCXO output (R425 – end not connected to C425) is 26MHz and approx.
700mVpp
If this is not the case check the reference crystal (B600) and Mjolner (N600) as well as
R425, R426, C425, C426.
In Phoenix select connection Fbus and Product Gemini. If you power up the board before
selecting Fbus, it works without any error messages. Use Jig or other device for RF and
bus connection. Attenuation in the probe alone is 0.5dB for 900 and 1dB for 1800. Use
CMD55 or other suitable device. Default channels are 37 for GSM900 and 700 for
GSM1800. The alignments and calibrations must be performed in the order shown to
give reliable results.
The way to save data to the phone and to load data from the phone is made different in
the various tunings. Always look what is shown in the windows regarding these issues
and act accordingly.
To vary a selected parameter you can use + and – key or in some cases directly type the
new value. + and – steps the value for every press. Repeat function seems not to work. In
I/Q you can use the side arrows.
This menu can be placed in maintenance or in tuning dependent of Phoenix.
It is meant to check the receiver or transmitter without going in call. It works very much
like a call, but you have control via the PC, and not via the tester. The TX mode GSM900
can select between Free, High and low mode. It changes the PA mode, but changes also
the power level if a level is selected that is not supported in that mode.
If you want to tune at other channels than the default, then you must select it first in RF
control and then start the tuning.
If all tunings are done, and the phone TX and RX is working a call is the ultimate test of
the phone.
Set CMD55, or similar tester, to manual test and switch the phone to normal if it was in
local. Remember to have a test simcard in the phone.
When the phone has made a registration a call can be made, and it is possible to let the
phone answer via Phoenix. In the Autocaller (Maintenance Testing) you can answer by
ticking Answer when button pushed and then posh the button.