Rx Front-End Ic (N7150) Dc Troubleshooting - Nokia 2255 Manual

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Rx Front-End IC (N7150) DC Troubleshooting

There are two common explanations for an N7150 failure consisting of high current in
Local Mode with just the Rx turned on:
• No presence of an LO signal
• Input impedance drop shorting out one of the DC supply pins to the chip.
IMPORTANT: You must check for both conditions before replacing the chip. If you
have no LO signal, refer to "UHF Synthesizer" on page 56. If you have a significant supply
voltage drop on one of the supply pins, then replace the N7150.
.
Condition: Local Mode, Set
Rx Only in RF Main Mode
Good mobile terminal
No UHF LO signal present
Pin 13 shorted
ISSUE 1 10/2005
Table 3: N7150 Conditions and Supply Currents
©2005 Nokia Corporation
RF Description and Troubleshooting
Supply Current
(From Power Supply)
100mA
254mA
255mA
Company Confidential
2255 (RM-97)
Page 29