Nokia 3510 Service Manual
NHM-8NX
Troubleshooting Instructions
PAMS Technical Documentation
Page 18
ãNokia Corporation
Issue 1 05/02
RF Troubleshooting
Two types of measurements are used in the following. It will be specified if the measure-
ment type is "RF" or "LF".
ment type is "RF" or "LF".
• RF measurements should be done with a Spectrum Analyser and a high-fre-
quency 500 ohm passive probe, for example HP54006A. (Note that when mea-
suring 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).
suring 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.
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.
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 mois-
ture sensitive so parts must be pre-baked prior to soldering.
ture sensitive so parts must be pre-baked prior to soldering.
Apart from key-components described in this document there are a lot of discrete com-
ponents (resistors, inductors and capacitors) for which troubleshooting is done by check-
ing 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.
ponents (resistors, inductors and capacitors) for which troubleshooting is done by check-
ing 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.
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 sig-
nal lines are shown in blue. Signal lines which is common for both
GSM 900 signal route is shown in red, the GSM1800 route in green and the common sig-
nal 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 volt-
age is present at VANT2 and VANT1 the switch works as a diplexer and the GSM900 sig-
nal is passed through the RX/TX switch to GSM-RX and the GSM1800 signal is passed to
DCS-RX.
age is present at VANT2 and VANT1 the switch works as a diplexer and the GSM900 sig-
nal is passed through the RX/TX switch to GSM-RX and the GSM1800 signal is passed to
DCS-RX.