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: RH-48 RF components
• 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 VCTCXO is centered as described in the VCTCXO tuning description on page 31.
• 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:
1Verify the current (0.7 - 1A for max power, mode, and channel dependent).
2Use a microscope to visually inspect the PWB for proper placement, rotation, and
soldering of components.
3Look for the presence of a Tx signal on the spectrum analyzer at the correct fre-
quency:
• 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.
4Verify 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.
5Check the LOs for proper frequency and amplitude.
6Ensure that the power supplies to the transmitter have the correct voltage.
Note: Be sure that the “RF Main Mode set successfully...” message appears in the status bar.
5Select the Rho ON check box on the CDMA Control dialog box.
Figure 5: CDMA Control dialog box for Tx troubleshooting
6Click the Execute button.
7At this point you should be able to measure Tx Pout at the RF connector. The cell
band Tx Pout =0 to 2dBm. If you do not see these values, set the AGC PDM for
25dBm and probe the Tx path to figure out where in the path the fault occurs.
8Open the General I/O dialog box to set the PA gain state.
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
The following table indicates the test points 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.
Figure 8 shows each testing point from the Cell Transmitter Test Path table for the Jedi
TXIC section. Always attach a 20dB 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.
Figure 9 shows each testing point for the PA section from the Cell Transmitter Test Path
table on page 10. Always attach a 20dB 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.
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.
PA Power and Gain Specifications
ModeName
Tx AGC
PDM
Value
PA Power and Gain Measurements
Power Amplifier Input
Test Point
pin3-Z601left-R814
Power
Output
Range
Target
Power
Low LimitHigh Limit
Power Amplifier Output
Test Point
Nominal
Gain
Vcc Range
Vcc Test
Point
Gain mode 0V0up to 623.80.75- 0.88C806
Gain mode 1V16 to 1125.21.125- 1.375C806
Gain mode 3V2Not usedNot used2 - 2.5C806
Gain mode 2Bypass11 up293 - 4C806
Overall GainV0 to
Bypass
unitN/AdBmdBVDCN/A
Phoenix Control and Example Values
PA Gain Step
Gen IO 12 GenIO13
LL0.8V0
HL1.2V1
LH2.2V2
HH3.7Bypass
63.5 to 7.3
+/- 0.5
PA Vcc
volt (v)
Spec
Name
*Not an actual FlaLi tuning PDM. PDM to produce approximately 25dBm at antenna connector.
The following Cell CDMA Channel 384 (Skyworks PA) table illustrates the PDM values and their
typical values for the IF AGC, RF AGC Jedi Pout, gain steps, and the PA VCC levels. This table also
shows the typical power output at the RF connector.
Cell CDMA Channel 384 (Skyworks PA)
Tx RF AGCTx IF AGCJedi Po
PDM
-2900.45Bot-
-1960.59-1960.59-2HH3.612820
-950.75-950.75-9.2HH3.672813.2
-950.75-950.75-9.2HL1.22611
-480.83-480.83-13HL1.225.87
-480.83-480.83-13LL0.8224.56
170.93170.93-19LL0.820
801.04801.04-29LL0.82-10
1201.111201.11-39LL0.82-20
1681.191681.19-49LL0.82-30
2491.322491.32-59LL0.82-40
Typical
Value
Test
Point
tom
C606
PDM
-2900.45Top
Typical
Value
Test
Point
C605
Typical
Value
3pin 1
Test
Point
Z601
PA Gain
Step
Gen
Gen
IO
13
Typical
Value
IO
12
HH3.47C806DM25
PA Vcc
Test
Point
PA
Gain
Conn
RF
Pout
3241.493241.49-69LL0.82-50
Cell Power Detector
The following tables illustrate the measurements required for troubleshooting the cell
power detector.
Figure 10 illustrates a simplified block diagram of the transmitter. The figure shows every
major component from I and Q baseband to the antenna port.
Note: See the Schematics chapter for an RH-48 transmitter schematic.
Receiver Troubleshooting
Rx IF
Use Phoenix to perform the following steps for troubleshooting the receiver. Together
with the VCO frequency and level verification, this test should be the first test for a nonworking receiver. This test verifies the entire receiver chain, from input connector to
baseband output.
1Inject a CW signal 881.82MHz or 881.22MHz (CH-384 offset by 300KHz) at a
fixed –75dBm power level. If you do not have a signal generator, use the CALL
BOX in AMPS mode on Channel 374 or 394 (10 channels away from
channel 384).
The following Rx RF Troubleshooting table indicates the test points to probe when troubleshooting the Rx RF. It is recommended that you follow the steps in order.
Rx RF Troubleshooting
Typical Value/
Step #Part*Function
R1L802R (Top
side of the
PWB)
R2L906LLNA-In-35dBm/
R3C903LLNA-Out-13/-31dBm
R4Z901-R-Bot-
tom, N901Pin16
R5C906RMixer-
R6C912B/R914RIF Output
R7R912B/R911LL.O Input
RF-IN-25dBm/
RF Filter
Output
Mixer-In
out
to N700
to N901
Frequency
HP85024A
881.52MHz
881.52MHz
881.52MHz
-18/-35dBm
881.52MHz
-5/-21dBm
183.6 MHz
+1.5/-15dBm
183.6MHz
-2.5dBm
1065.12MHz
Typical Value
Frequency
Prod Probe
-42dBm
881.52MHz
-42dBm
881.52MHz
-29/-45dBm
881.52MHz
-30/-45dBm
881.52MHz
-23/-38dBm
183.6MHz
-12/-29dBm
183.6MHz
-18dBm
1065.12MHz
Comments
Input Connector reference level
Test Duplexer insertion Loss
(Without DC Block)
Test LNA gain ~ 13dB
Test RF Filter Insertion loss
(Without DC Block)
Test Output on Downconverter on
N901
Test Alfred output to Yoda IF-IC
(N700)
Test VCO output to Alfred (N901)
Levels are for Channel 384
R8R9056T, L909L,
L901T, R910B
R9R902BRx-SW1H.G = 2.7V
* 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 17.
VR42.7V dcPower supply to Alfred (N901)
L.G = 0V
LNA gain control, on the Alfred
side, High Gain > 2.5V dc
Figure 17 shows the Rx RF testing points from the Rx RF Troubleshooting table.
Antennae
Connector
(other side)
R1
Figure 17: (Top left) PWB. (Top right) The antenna connector on the opposite side of the PWB, (Bottom left)
A zoomed view of the testing points on the Rx RF section. (Bottom right) A zoomed view of the Rx RF section
-950..633Note the reduced delta because the LNA is
-1000.594
-1050.524
-1070.470
UNITSVDC
Receiver Block Diagram
Figure 18 illustrates a simplified block diagram of the receiver. The diagram shows every
major component from the antenna port to the I and Q baseband.
Note: See the Schematics chapter for an RH-48 receiver schematic.
CELL
RF AGC
Comments
switched on
Figure 18: Receiver block diagram
Synthesizer Troubleshooting
Faulty synthesizers can cause both Rx and Tx failures during tuning, in addition to the
VCTCXO tuning. The following synthesizers are incorporated into the RH-48:
Note: Be sure that the “RF Main Mode set successfully...” message appears in the status bar.
5Read register templates Jedi(0) bits 10 and 11 for the UHF and Tx VHF lock condi-
tion on the RF Register R/W dialog box.
6Read register templates Yoda(0) bit 11 for the RX VHF lock condition.
VCTCXO Tuning
The VCTCXO can be manually tuned to verify failed tuned phones, or to verify if a phone
cannot make a call. This can be done with the phone in Local Mode and generating a CW
signal. The frequency accuracy of the VCTCXO can be measured using an HP8960 callbox
in AMPS mode, an HP4406 Tx tester, or a spectrum analyzer (preferably using a lab system 10MHz source as equipment reference). Replace the VCTCXO if the VCTCXO AFC DAC
value does not meet the tuning requirements after tuning.
Figure 21: RF Register R/W dialog box for synthesizer setup
which gives either a pass or fail result
only. The phone transmits at several
power levels and checks the ADC value
of the power detector. The ADC value is
measured first for a set of AGC values,
then each AGC value is changed one at
a time to make sure that the ADC
changes as each AGC is changed individually.
Cell PA TempThis is one of the phone's self tunings,
which reads the ADC voltage of a thermistor R821, and checks to make sure
the phone is at room temperature. The
reason for this is that a phone should
not be tuned while it is hot or cold.
Check the AGC voltages and components of
the associated PDMs. For problems with the
IF or RF AGC, also check Jedi and supporting
components. For PA AGC problems, also
check the PA and supporting components. If
all of the above cases fail, troubleshoot the
Tx chain. If all the output powers are passing, then perhaps the test is failing because
the ADC voltage is wrong (which at this
point we cannot read, so we are measuring
the actual output power). If the voltages are
wrong, then check the power detector at
N805, C803, C807, and also Jedi. If the voltages are correct and it still fails, check the
UEM ( D200).
If the phone was recently transmitting in
Cell band at full power for an extended
period of time, it is probably hot for that
reason. Let it cool down for a few minutes,
then try again. If it still fails, there may
either be a short on the board or else a
problem with the PA Temp circuitry. To
check PA Temp circuitry, check R821 and
D200. If a short is suspected, check the cell
PA first. If an infrared camera is available,
this is one of the easiest methods to detect
a short.
Cell Rx DC Offset I
(or Q)
Tx Start-up CurrentThis test turns on the transmitter and
Tx Start-up AmplitudeThis test turns on the transmitter and
This is one of the phone's self tunings,
which measures and adjusts the cell
band CDMA receiver DC offsets until
they are within the limits.
measures current of the whole phone,
which can detect some assembly errors.
checks for the presence of a Tx signal
with an amplitude within a specified
range. A wide range is allowed since the
transmitter is not yet tuned.
Check Yoda (N701) and supporting components.
If current is very high, there may be a short
circuit on the phone caused by a solder
bridge, a failed component that is internally
shorted, a component placed with the
wrong rotation which shorts two nodes that
should not be, or some other reason. A visual inspection can find solder bridges or
wrong component rotations. A failed component can be found by functional tests of
the phone's sub-blocks.
Check proper placement, rotation, and soldering of the components in the Tx chain.
Check for the presence of LO tones. Check
for the presence of a Tx signal at each point
in the Tx chain.
VCTCXO FrequencyThe purpose of this tuning is to deter-
mine what the AFC DAC value needs to
be in order to center the VCTCXO frequency. The transmitter is turned on and
no Tx baseband modulation is provided.
The carrier is then centered in frequency.
This is done to the carrier after it has
been mixed up to 836.52MHz, since it's
easier to measure the tolerance of 1ppm
at 836.52MHz than it is at 19.2MHz.
Additionally, the tone at 836.52MHz can
be measured without taking the phone
apart.
1) If there is no tone, probe pin 3 of G501
for a tone at 19.2 MHz. If this is not present,
check power supplies, particularly ensure
2.7v on VCTCXO Vcc pin, pin 4 of G501.
Also check the control pin, pin 1 of G501,
for a voltage between 0.4 and 2.7v. If the
voltages are correct, and soldering of all
G501 terminals is correct, replace G501. If
19.2 MHz tone is present but tone at
836.52 MHz is not, troubleshoot cell Tx
chain.
2) If the carrier is present but the PDM
needed to center it is outside of the +/- 150
range, or if it cannot be centered, there is a
hardware problem.
3) In the following procedure, performing
frequency centering on the RF carrier at
836.52MHz will detect frequency errors due
to the VCTCXO and supporting hardware,
which will account for the majority of the
problems, but will not detect frequency
errors due to the hardware that mixes the
VCTCXO tone at 19.2MHz up to 836.52MHz.
In order to troubleshoot this hardware, frequency centering should be performed on
the 19.2MHz tone to +/- 19.2Hz on pin 3 of
G501 using a frequency counter, then the
VHF and UHF LOs should be checked.
Because this will be time-consuming and
will probably only account for a small percentage of the failures, it is not recommended unless the situation justifies the
time spent. The VHF LO is inside the Jedi IC
(N601) and troubleshooting of the cell UHF
LO is required.
4) If the carrier can be centered but the
PDM is out of range, check the control voltage on pin 1 of G501. If it is 2.2v, (and pin 4
is at 2.7v, and pin 2 at 0v), then the
VCTCXO (G501) is working correctly but the
circuit that delivers the control voltage is
not. Check soldering of all G501 terminals,
also check R510, R511, C503, and D200. If
the control voltage on pin 1 of G501 is not
2.2v, but the carrier is centered, then there
is a problem with the VCTCXO G501. If there
is 2.7v on pin 4 and the soldering is correct,
then replace G501.
5) If the carrier cannot be centered, check
to see if you can adjust to 2.2v on pin 1 of
G501. If you can, within the PDM range of
+/- 150, then the circuitry that delivers the
voltage is working correctly, and the
VCTCXO has a problem. Troubleshoot it as
described in the previous section. If you
cannot adjust to 2.2v within the accepted
range, then the AFC circuitry has a problem.
Troubleshoot it as described in the previous
section.
6) If there is a fault with both the AFC circuitry and the VCTCXO, then several combinations of the previously described
conditions are possible. Start by ensuring
2.2v on pin 1 of G501 using a PDM within
the range +/- 150, then center the tone.
PA Gain Cell Po(0)Po(3)
Tx AGCThis tuning characterizes the AGC curve
These tunings model the cell PA gain
curve by setting the PA AGC PDM to
several values and measuring output
power. First, the Tx PA AGC and the Tx
RF AGC are set to (approximately) their
maximum used values (not the maximum possible values, but the maximum
of the range over which they are used).
Then the Tx IF AGC is set so that the
transmit power on the antenna connector is approximately +11dBm (this power
is reported in the next tuning). Then, six
PDM values are written to the PA AGC
and the output power is measured for
each. These values are reported in this
tuning. The software then performs
curve fitting to interpolate between the
measured data points.
by entering PDM values to the RF AGC
and measuring the output power.
If the power readings are low, check the
AGC voltages. You can also probe on the PA
input to find out if the power level is low
going into the PA, or if the power level is
correct going into the PA but the PA gain is
too low. If the power level going into the PA
is too low, probe the Tx chain at all the
other points prior to the PA listed in the
table to see where the gain is lacking. When
that point is identified, check the soldering
of all related components, and replace components until the fault is found. If the
power on the PA input is not low and the PA
AGC voltage is correct, similarly probe the
power at all points after the PA to find the
fault, being extremely careful not to short
the probing point to ground because this
will instantly destroy the PA. Visually check
soldering first, and probe on PA output as a
last resort.
Check Jedi (N601). Also check D400, which
generates the PDM signals. Check AGC PDM
voltages. Troubleshoot the rest of the cell
transmitter if needed.
TxdBCtr correctly corresponds to the
absolute Tx output power. On the mid
channel, with TxdBCtr set to a specified
value, G_Offset is adjusted so that the
output power is -8dBm, and that value
of G-Offset is recorded (which is an
absolute value) in the next tuning. The
output power in dBm is recorded in this
tuning.
TN G_OffsetSee description of previous tuning. This
step reports G_Offset.
Tx Limiting CellThis tuning provides an upper limit on
the transmit power while in Cell IS95
mode. The reason for this is to ensure
that the phone never goes above the
maximum transmit power level. After
this is done on the mid channel, the
channel is changed to each of the other
channels, and detector offset is
reported.
Set the phone to local mode and program it
to Cellular CDMA Rx/Tx mode on channel
384, using the Main Mode window. Using
the Phoenix RF Tuning window, choose
mode = RF Tuning, and choose this test.
Adjust G_Offset in the "Values” dialog box
line until the Tx output power (measured on
the RF connector with a spectrum analyzer)
is equal to -8.0dBm +/- 0.5dB. Use the
G_Offset limit range as a guide to which
values to enter.
If G_Offset is not within the limits, troubleshoot the Cell Tx.
If the maximum cannot be reached, either a
component in the transmitter has too much
loss, or not enough gain. Troubleshoot the
transmitter, with the phone set to the same
channel as the failed channel. Once this is
done on the center channel, change to each
of the other channels, and record the power.
Do not adjust G_Offset on the other channels, just record the power. It should be
within the limits listed in the tuning results
file.
Rx IF AGC Rx dB CtrThis tuning calibrates the Rx IF AGC
curve. The tuner injects three known
signal power levels into the phone's
receiver, and for each one the phone's
AGC algorithms, adjusts the RX_IF_AGC
to get the same amplitude at the output
of Yoda, although different amplitudes
are going in. From these three points,
curve fitting is used to interpolate
between measurement points.
LNA GainThis tuning records RxdBCtr (which is
automatically adjusted to produce the
same amplitude on the receiver output
no matter what the input is) for the
receiver with the LNA in high gain mode,
and again with the LNA in low gain
mode.
While injecting a signal into the receiver,
check the values of RX_IF_AGC PDM value
and, if needed, voltage. RSSI should be
within +/- 2 dB of the actual power in dBm
on the RF connector. The AGC will try to
keep the same amplitude on Yoda output;
therefore, if the AGC value is larger than
normal, then the AGC is compensating for
loss in the chain prior to the variable gain
amplifier.