HP 8753E - Page 325

FN LO at Al2 Check
1. Use an oscilloscope to observe the FN Lo from.&14 at the cable
end of A14J2. Press (jj) (SystemJ ~~~~~,~~~~.. :~~~~.~~~~~~
. . . . . . . . . . . . . . . . . . i : . . . . . . . . . . . . i . . . . . . . . . . . . . ~,............../..~.....
-.::: .:.<... :: . . . . ..U.L _.... :..<.ti.: . ..__ :<. .:.,...... .
. . . . . . ~...W~ . . . . . . ..~................
.v.
:::::.
. . . . . .
-FM%% TWE:n#. to switch on the fractional-N service mode.
: . . . . . . . . :4.:. ,.,....,__...._.... - . . :: . . . . . . . . . . . . . .<..<.:
2. Use the front panel knob to vary the frequency from 30 to 60 MHz. The
signal should appear similar to Figure 7-l 1. The display will indicate 10 to
60.8 MHz.
q If the F’N Lo signal is good, the Al2 assembly is faulty.
q If the FN Lo signal is not good, skip ahead to “A13/A14 Fractional-N
Check”.
-50.000 -
0.00000 SPD
50.000 n*c
la.2
- 100.0 mvolts/div
Timdaaso -
10.0 rises//iv
sg613s
Figure 7-11. Typical FN LO Waveform at A12Jl
SouroeTmbleshooting 7-19