HP (Hewlett-Packard) HP 85660B ユーザーズマニュアル

The triggered sweep modes are very similar to free run operation except that instead of the

Al5 Controller outputting a set HSWP command to the A3Al Trigger assembly, it outputs a
trigger enable command. The output of the trigger select circuit (line, external, or video) then
clocks the HSWP line high.

The single sweep mode is useful in troubleshooting the sweep system because it does not rely
on feedback from Digital Storage before resetting the sweep generator. Whenever the SWEEP

 key is pressed, the Al5 Controller resets the sweep generator and then sets HSWP

high through the A3Al Trigger assembly. Digital Storage then stops the sweep when it has
reached the end and the ramp resets to 0 V.

Fast sweep is enabled only for 0 Hz frequency spans and sweep times less than 20 ms. HSWP

is forced low, and the Al6 Sweep Generator is not used. See A3Al Trigger for a description of
the fast sweep operation.

Any of the Service Requests on the Al2 Front-Panel Interface will force LSRQ low which
forces HSWP low. For example, when a front-panel key is depressed, a keyboard Service
Request is generated. LSRQ goes low, LSTP goes high, and HSWP goes low stopping the
sweep. Depending on which key was pressed, the Al5 Controller will either continue the
sweep or reset it and start a new sweep. Note that the analyzer cannot sweep if any Service
Requests are present.

The following procedure is an aid to rapidly isolate sweep system malfunctions. When the

malfunction has been traced to a single assembly, check the Service Sheets for that assembly
for a more thorough troubleshooting procedure.

Disconnect the ramp from A3A8Jl  and jumper A3A8TPl  to A3A8TP2.  This forces the ramp
comparator output high. The Digital Storage Processor Section should continue to process
data and increment the sweep address. The HSWP light should be flashing and HSWP should
have an approximately 16 ms pulse width. (Note that the instrument preset state may appear

to be functioning properly but will become distorted as the sweep time is slowed down.)
If this works, the Digital Storage Processor Section and Al5 Controller, Al2 Front-Panel
Interface, and A3Al Trigger assemblies are operating properly. Suspect the ramp generator
or Al6 Scan Generator or ramp converter on the A3A8 Analog-Digital Converter. To further
isolate the scan generator, reconnect the sweep ramp to A3A8Jl  and remove the jumper. Set
the sweep time to 1 second and press the SWEEP 

 key. The ramp waveform will start

at greater than 10 V, go to 0 V when the SWEEP 

 key is pressed, and ramp back

Overall Troubleshooting 11