User Guide

Nokia Customer Care Troubleshooting - RF

6015/6015i/6016i/6019i (RH-55), 6012 (RM-20)

Alfred (N750) Receiver Troubleshooting

Keep the following under consideration when troubleshooting the Alfred (N750) receiver:

• There is a separate LNA for 800MHz (Cell and AMPS) and 1900MHz (PCS).

• There is a separate RFA (inside Alfred) for 800MHz (Cell and AMPS) and

1900MHz (PCS).

• After the RFA, there is a mixer and then the signals are separated by CDMA (Cell

and PCS) and AMPS.

For example, if there is no IF frequency (128.1MHz) check both Cell and PCS. If

there is only one at 128.1MHz (L753), ensure that IF_SEL is working. If it is, then

replace Alfred because of a bad RFA.

If Cell and AMPS are working but PCS is not, look at the band select line and the

PCS RF filter before replacing Alfred.

Figure 32: N750 (Alfred) receiver

Alfred DC Troubleshooting

There are two common explanations for an Alfred failure consisting of high current in

Local Mode with just the RX turned on:

• No presence of an LO signal

• Input impedance drop is shorting out one of the DC supply pins to the chip

IFAs

Buffer

PCS

RFA

PCS

LNA

Cell

LNA

Cell

RFA