HP 5334B Service Manual page 191

8-441. Determining the Failed Circuit in the Channel C Block
8-442. To troubleshoot the Channel C Block, you must determine which of the following three categories the
problem falls into:
The Peak Detector does not enable the Divider, resulting in no output at pin 4 of U302 (Divider).
The Peak Detector properly enables the Divider, but the output of Divider (Pin 4 of U302) is in-
correct or nonexistent.
The Peak Detector improperly enables the Divider. The Counter works properly with a signal ap-
plied to Channel C, but it randomly counts when the signal is removed from the Channel C input.
8-443. The following procedure will help determine which category a failure falls into. Note that U306 pin 1 is
the output of the Peak Detector. When pin 1 is at
-
1.2V
2
0.4V, the Peak Detector enables the Divider; and
when pin
1
is at
-
5V
2
0.4V, the Peak Detector disables the Divider.
8-444. The flowchart in Figure 812, simplifies the Channel C troubleshootingprocedures.
I
9 0 MHz OR 9 9 0 Wz
SIGNAL TO INPUT C
I
MONITOR
U306 P I N 1
NOT - 1 . 2 V
?
0 . 4 V
1
REMOVE SIGNAL
TO INPUT C
CHECK OUTPUT
OF U303 P I N 1.
( 3 0 d B AMPLIFIER
n
OUTPUT
9 0 OR 9 9 0 MHz
I
I
NO OUTPUT
I S PRESENT
( 9 0 OR 9 9 0 MHz
NOT PRESENT)
THRESHOLD COMPARATOR AMPLIFIER I S WORKING.
THRESHOLD COMPARATOR
TROUBLESHOOTING
TROUBLESHOOTING TROUBLESHOOTING TROUBLESHOOTING.
(PARAGRAPH 8-453:
(PARAGRAPH 8 - 4 4 7 ) (PARAGRAPH 8 - 4 4 9 ) (PARAGRAPH 8 - 4 4 5 )
*NOTE THAT WHEN THE COUNTER OPERATES PROPERLY WITH THE 9 0 MHz INPUT
SIGNAL, REPEAT THE STEPS I N THIS FLOWCHART WITH THE 9 9 0 MHz INPUT SIGNAL
HP 5334B
-
Service Manual
8-71