Differential Signal Output; Inhibit Input; Trigger Output - HP 8114A Service Manual

Differential Signal output

Warning

Inhibit Input

Trigger Output

This measurement has to be done against floating ground FLGND.
Floating Voltages up to 130 VFL are present, which are hazardous
to life.
1. Connect the oscilloscope probe ground (GND) to FLGND on the
timing board. FLGND can be accessed on one pole of R726, close to
the border of the board.
Check
2. at U703 pin 2 and pin 3 for a differential signal output.
2. Enable the output by pressing (SHIFT), @ (ON/OFF).
3. Apply a 5 Vdc signal to the INH INPUT.
4. Check with an oscilloscope that the output is inhibited when the
external inhibit signal is applied.
1. Check at junction R801, and R802 for a signal with 50 % duty
cycle, and EECL levels (high level at 0.0 V, low level at -0.7 V).
2. Check at the collector of Q801 for a 50 % duty cycle signal with
high level at -1.9 V, and low level at -2.9 V.
3. Check at the collector of Q802 for a 50 % duty cycle signal with
high level at -1.9 V, and low level at -2.9 V.
4. Check at R815 for a 50 % duty cycle signal with TTL levels.
in the OUTPUT page.
Troubleshooting 5-15