Fmtx2.1 Specific Rf Test Points; Specific Clock Test Points; General Visual Inspection Guidelines - Nokia RM-484 Service Manual

RM-484; RM-485; RM-486
FMTx 2.1 Troubleshooting
_SEN
The _SEN pin is used to select one of two possible 7-bit I2C bus addresses. When _SEN is low, the I2C bus
address for the Si4713 device is 0010001 (0x11). When _SEN is high, the I2C bus address for the Si4713 is
1100011 (0x63).
If the _SEN signal is not correct (i.e. not selecting the correct I2C address), then this is also another possible
reason why control of the FMTx 2.1 feature might not be possible. For RM-484 the I2C address used for FMTx
2.1 will be 0x63.
I2C address
0010001 (0x11).
1100011 (0x63).

FMTx2.1 specific RF test points

TXO
Pin 4 is the TXO pin. This is the transmitter output pin and probe access can be obtained easily. Using a high
impedance probe and a spectrum analyser it would be possible to examine the TXO pin and check that the
transmitter is outputting a signal.

Specific clock test points

RCLK
Pin 9 is the RCLK (Reference Clock) input to the device. This is typically 32.768KHz and is driven from the sleep
clock from the base band. When measuring this clock frequency, it may be seen to vary by as much as +/-
120 ~ 200ppm. The device can only typically tolerate +/- 20ppm in order to maintain transmit frequency
accuracy. To overcome this, the software driver for the device calculates what the actual sleep clock (RCLK)
frequency is and periodically programs the device with this frequency.
The device then internally adjusts its dividers in order to maintain the required output frequency. Using this
method it is possible to reduce the effective ppm of the reference clock down to +/- 14ppm over the full
operating temperature range of -15 to +50 degrees Centigrade.

General visual inspection guidelines

• If the handset has the FMTx antenna in the back cover then check the condition of the cover, the antenna
trace and any mechanical interfaces for the antenna e.g. pogo pins.
• Check that the Si4713 device is placed correctly on the PWB and that there are no obvious signs of damage.
• Check the surrounding components and ensure correct placement on the PWB and that there is no visual
damage. Check that there are no missing components.
Issue 1
Table 7 I2C 7-bit bus address selection summary
_SEN
High
Low
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