HP 70908A, Service Manual

Page: 71 / 335

If Y ou Have A djustment Procedure F ailures
If A djustment 05. LOLA Tuned Filter F ails
If A djustment 05. LOLA Tuned Filter fails , the failure is most likely the A1 leveling amplier .
P erforming A djustment 01. LOLA Gate Bias and A djustment 04. LOLA P ower Out verify that
the A1 leveling amplier stays leveled over an LO input frequency range of 3 GHz to 6.6 GHz
at power levels of +5, +8, and +12 dBm.
T o solve this problem:
1. P erform A djustment 04. LOLA P ower Out.
2. If procedure still fails , troubleshoot the A1 leveling amplier .
3. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If A djustment 06. SYTFMD Oset Coil F ails
If the oset coil current for the A3 SYTFMD cannot be adjusted within test limits , the problem
is most likely the A10 power supply/driver .
T o solve this problem:
1. Remove A10J203. Measure the resistance between pin 8 and pin 9. A measurement
between 6 to 8 ohms indicates a good A3 oset coil.
2. Replace the A3 SYTFMD if needed.
3. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If A djustment 07. SYTFMD Main Coil Preset or A djustment 09. SYTFMD
Main Coil Alignment F ails
If either adjustment fails , analyze the failure to determine the location of the malfunction.
T o solve this problem:
1. P erform A djustment 06. SYTFMD Oset Coil.
2. If A djustment 07. SYTFMD Main Coil Preset still fails , refer to troubleshooting the main coil
drive in the A10 power supply/driver .
3. If the main coil drive is not the problem, troubleshoot the A3 SYTFMD .
4. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
If A djustment 08. Multiplier P ower Leveling F ails
If A djustment 08. Multiplier P ower Leveling fails , analyze the failure to determine the location
of the malfunction.
T o solve this problem:
1. V erify that the input power to the A2 LO multiplier is 15 dBm.
2. If the power is not 15 dBm, troubleshoot the A1 leveling amplier .
3. If the power is 15 dBm and the adjustment cannot be made , troubleshoot the
A2 LO multiplier .
4. If the failed assembly is not located, the problem is either on the A13 ALC/bias or
A2 LO multiplier .
5. If necessary , obtain service from Hewlett-P ackard. (Refer to \If Y ou W ant Hewlett-P ackard
to Service Y our RF Section " in Chapter 1.)
4-10 T roubleshooting