HP 8562E Service Manual page 370

DEF 1
x
Y POS
Frequency-Count Marker Problems
The FREQ COUNT function works by dividing the 10.7 MHz IF signal by two (prescaling)
and counting the divided-down signal using the frequency counter on the A2 controller
assembly (block Z of the A2 schematic diagram). The prescaler is on the A4 Log amplifier/Cal
oscillator assembly (block Q of the A4 schematic diagram). Perform the following steps to
determine whether the problem is on the A4 log amplifier/Cal oscillator or A2 controller
assembly:
1. Disconnect W53 from A2J7.
2. Connect the output of a synthesized source, such as an HP 3335A, to A2J7.
3. Set the synthesized source to the following settings:
Amplitude . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +lO dBm
Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.35MHz
4. Set the spectrum analyzer to the following settings:
Center frequency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...300 MHz
Span . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..lMHz
5. On the spectrum analyzer, press
half the frequency of the 10.7 MHz IF. If the CNT frequency display reads all asterisks, the
frequency counter is probably at fault.
6. If valid frequency is displayed, troubleshoot the prescaler on the A4 log amplifier/Cal
oscillator assembly.
7. Reconnect W53 to A2J7.
5 . 0 0 0 . 0 0 v
I
Figure 10-l 1. DEFl Synchronization
The frequency counter actually reads one
( ).
FREQ COUNT
5 . 0 m s / d i v
0 . 0 0 0 s
Controller Section
SK1 100