Nokia 6560 Service Manual 8rh25rf

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 ........................................................................................ 3

Fault finding charts for receiver chain ...................................................................... 4

Transmitter Troubleshooting .......................................................................................9

General instructions for TX troubleshooting ............................................................ 9

Path of the transmitted signall................................................................................... 9

Fault finding charts for the transmitter.................................................................... 10

Synthesizer Troubleshooting .....................................................................................16

19.44 MHz reference oscillator............................................................................... 16

RX VHF .................................................................................................................. 17

TX VHF................................................................................................................... 17

UHF Synthesizer..................................................................................................... 18

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CCS Technical Documentation Troubleshooting - RF

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.

Receiver Troubleshooting

General instructions for RX troubleshooting

Start the Phoenix software and use it to start the required RX-mode of the mobile phone.
The troubleshooting flowchart is divided into three steps: (1) general checking, (2) local
checking and (3) RX-chain checking.

Note: Before changing ASICs or Filters, all solderings and missing components must

be checked visually. After any possible component changes, the phone must be
tuned with the Phoenix autotune SW.

Path of the received signal

Block level description of the receiver:

(Antenna/ext RF) – Diplexer – Duplexer – Low Noise Amplifier (LNA) – RX band filter –
First mixer – 135.54 MHz RX IF filter – IF-amplifier – second mixer – 14 kHz low-pass fil­ter – adjustable IQ amplifier – Baseband.

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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

N

Y

AMPS RX chain OK

Check UHF Vc (from

C773) V: 1.8 ... 2.1V

Y

Check RXVHF Vc

(from C720)
V: 0.7 ... 1.3

Y

Apply 881.49MHz

-30dBm, sine signal

external RF connector

(X900)

N

N

Start troubleshooting

Start troubleshooting

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CCS Technical Documentation Troubleshooting - RF

Check input level at

diplexer (Z907)

Y

Check input level at

duplex filter

Y

Check input level at

LNA input

Y

Check RF level at

RX800 band filter

input

N

Change EXT RF

connector

soldering and
components in
antenna circuit

before changing.

NOTE: Check all

NOTE: Check all

N

Change diplexer

(Z907)

soldering and

discrete

components of

front end.

N

Change duplex filter

(Z906)

NOTE: Check all

solderings and

N

Change TACO (N801)

discrete components

around TACO before

changing.

Y

Check RF level at

MIX1Ain P/N

Y

N

Change TACO (N801)

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Troubleshooting - RF CCS Technical Documentation

Check RF level at RX

IF filter input at

135.54MHz

Check RF level at RX

IF filter output at

135.54MHz

Y

Check RX I and Q

signals at I: J801(+),

J803(-) and Q:

J804(+), J802(-)

Check RF level at

N N

J751 and J752 at

2034.06MHz

Y

Change TACO (N801)

N

Change RX IF filter

(Z830)

Check RF level by

N

L730 without having

electrical contact at

271.08MHz

Start synthesizer

troubleshooting

NOTE: Check all

discrete

components and

voltages around

TACO.

N

Start synthesizer

troubleshooting

Y

Check UEM and start

baseband

troubleshooting

Y

Change TACO (N801)

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CCS Technical Documentation Troubleshooting - RF

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 –> 1

st

IF needs separate troubleshoot at upper band. After down

conversion (RF –> 135.54 MHz) both lower and upper band use same signal path.

Apply 1960.02MHz =

ch1000 - 50 dBm

signal to external RF

connector (X900)

Y

Check RX I and Q

signals at I: J801(+),

J803(-), and Q:

J804(+), J802(-)

N

Check UHF Vc (from

C773) V: 2.2 ... 2.6V

TDMA1900 RX chain

Y

N

Start synthesizer

troubleshooting

is OK

Y

Check RXVHF Vc

(from C720).

V: 0.7 ... 1.3

Y

N

Start synthesizer

troubleshooting

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Troubleshooting - RF CCS Technical Documentation

Check input level of

diplexer (Z907)

Y

Check input level of

duplex filter

Y

Check RF level at
LNA input (at duplex
filter RX output port)

Y

N

Change EXT RF

connector

soldering and
components in
antenna circuit

before changing.

NOTE: Check all

NOTE: Check all

N

Change diplexer

(Z907)

soldering and

discrete

components of front

end.

NOTE: Before

N

Change duplex filter

(Z962)

replacing TACO,

check all the

solderings and

components around

V850.

Check RF level at

RX1900 band filter

(Z850) input

Y

Check voltage at

N

C854 out (V850 in).

Change TACO (N801)

V: about 2.7V

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CCS Technical Documentation Troubleshooting - RF

Y

Check RF level at

MIX1_B input

Y

Check RF level at RX

IF filter input at

135.54MHz

Y

Continue

troubleshooting like

LB

N

N

Transmitter Troubleshooting

Change RX1900 band

filter

Check RF level at

J751 and J752 at

2095.56MHz

Y

Change TACO (N801)

N

Start synthesizer

troubleshooting

NOTE: Check all

discrete

components and

voltages around

TACO

General instructions for TX troubleshooting

Always use an RF cable connected from an external RF connector to the analyzer via (rf­power) attenuator. This is important to protect the analyzer against excessive RF power
and not to allow leakage of undesired RF power into the cellular frequencies.

1 Start the Phoenix-software and select the TX mode under Testing (AMPS, DAMPS,

or TDMA 1900).

2 It is useful to select the mid channel (383 for AMPS/DAMPS or TDMA 1900) and

power level 2.

Note: After any component change, tune the phone with the Phoenix autotune SW.

Path of the transmitted signal

l

AMPS/DAMPS

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

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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

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.

3 Connect the RF cable to the Ext RF connector.

4 Connect the cable to the Spectrum analyzer input.

5 Measure the RF level.

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CCS Technical Documentation Troubleshooting - RF

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)

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

(836.49MHz) output

power from balun

1961 input RF:0dBm+/

-6dB

OK

NOK

NOK

NOK

Check UEM

(Baseband)

Change TACO or

Z960

Change TACO

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Troubleshooting - RF CCS Technical Documentation

Check TX SAW input

and output power

IL:-3dB

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 ~0.1

NOK

NOK

NOK

NOK

Change TX SAW filter

Z905 or T961

Change PA

Change N930

Change Z906 or RF

connector

OK

Start power

troubleshooting

TDMA800

The transmitter chain is exactly the same as the AMPS mode, except for the IPA current,
and thus it is important that the AMPS have no faults.

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CCS Technical Documentation Troubleshooting - RF

TDMA1900 (only dualband)

TDMA1900 mode and DAMPS mode have a common RF modulator.

TDMA1900, PL2,

CH1000

Is TDMA800 mode OK?

OK

Start synthesizer

troubleshooting

OK

Check supply voltage

-VR2

-VBATTRF

-IPA2

OK

Check TX IF input power

(180.54MHz) IF: -20 dBm

+3/-6dB

NOK

NOK

NOK

Start AMPS

troubleshooting

Check UEM and UPP

(Baseband)

Change TACO

OK

Check TX RF

(1879.98MHz) output

power @T960 input RF:

NOK

Change TACO

0dBm +/-6dB

OK

Check Z961 input and

output power IL: 2dB RF

NOK

Change T960 or Z961

in: 0dB+-

OK

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Troubleshooting - RF CCS Technical Documentation

Is ltot 350...450mA?

Check PA output power

and gain.

Output power: ~29dBm

Gain: ~30dB

OK

NOK

Change PA (N960)

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 ~0.1dB

OK

Start power control

troubleshooting

NOK

NOK

Change PWRDET

(N930)

Change Z906 or Z907 or

RF connector

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CCS Technical Documentation Troubleshooting - RF

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)

Y

Is DAC value vs.

PWRDET (mV) OK?

N

N

Check VR2 and

RFTEMP.

Check C930, C931, and

PWRDET module.

Check UEM (Baseband)

NOTE: See PWRDET

vs. Output power

curve

The detected voltages are illustrated in the following table and diagram:

Table 1: Typical detected voltages at power levels PL2...PL10 for dualband

800A 800D 1900D

Pout TXPWRDET Pout TXPWRDET Pout TXPWRDET

PL dBm dac mV dBm dac Mv dBm dac mV

2 24.8 686 1932 27.3 779 2201 27.0 696 1956

3 22.0 512 1437 23.3 476 1312 23.3 431 1198

4 18.5 340 961 19.3 284 759 19.3 262 730

5 14.5 239 686 15.3 171 462 15.3 158 445

6 10.5 180 510 11.3 98 271 11.3 88 253

7 6.5 141 415 7.3 56 151 7.3 50 148

8---3.330843.32679

9 - - - -0.7 14 46 -0.7 14 44

§0----4.75 16 -4.76 20

Note: DAC values may vary about +- 20%.

Note: TXPWRDET is the difference between TX on burst and off burst.

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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 271.08 MHz and TX VHF is fixed to 361.08 MHz . All locals
are locked to stable 19.44 MHz VCTCXO reference oscillator.

The frequency range for 2 GHz UHF VCO is: 2009.1 … 2125.53 MHz. The output fre­quency range for the lower band is from 2009.16 to 2059.02 MHz. In upper band the
output frequency range from the UHF VCO is from 2031.78 MHz to 2125.53 MHz.

It is a practical way to check out synthesizer status by measuring control voltage of the
VCO from Integrator capacitor. If voltage is stable and reasonable, local oscillators are
running correctly.

19.44 MHz reference oscillator

The VCTCXO oscillator frequency (G790) is controlled by UEM. This output 19.44 MHz
signal is connected to TACO. It is used as a reference signal in TACO and also fed out as
buffered clock signal to UPP. All synthesizers use divided 19.44 MHz signal as a reference
signal for Phase locked loop to provide correct LO frequency.

2

Change VCTCXO

OK

START HERE!

Is VCTCXO oscillating?

2 No

19.44MHz

1 No

Check voltage (C792)

2.78V

No

OK!

OK

1

OK

Check resistor (R792)

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CCS Technical Documentation Troubleshooting - RF

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.

1

3

Replace TACO

OK

2 No

START HERE!

Is frequency locked to

271.08MHz?

1 No

OK

Yes

OK!

2

Check resonator

components: L730,

C740, C741, R741

TX VHF

The TX VHF signal is used to generate transmitter intermediate frequency. TX VHF VCO
has one fixed frequency (361.08 MHz). Operating frequency is locked in phase locked
loop. TX VHF VCO output signal is divided by 2 and fed to the modulator.

TX VHF is integrated in TACO. There are only four external components, VCO coil (L746)
and loop filter components C720, C721, and R721.

3

Replace TACO

OK

2 No

START HERE!

Is frequency locked to

361.08MHz?

1 No

OK

Yes

OK!

2

Check resonator

components: L746,

C720, C721, R721

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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. Integrated charge pump circuit allows analog
and digital operation modes. The VCO oscillation frequency is from 2009.1 MHz to

2125.53 MHz. The output frequency of the VCO module depends on the DC control volt­age, which is controlled by the PLL circuit inside TACO.

Change VCO

OK

Check loopfilter

components and

balun

OK

3 No

START HERE!

Is frequency locked to

2034.06MHz?

OK1 No

Check VCO

operating voltage:

2.78V

No

OK

4 No

Check loopfilter

components

Check resistor

Is EVM OK?

1 No

(R774)

OK

Change TACO

2 No

YesYes2 No

OK!

Page 18 ©Nokia Corporation Confidential Issue 1 10/2003