HP 8112A Operating, Programming And Servicing Manual page 260

1 0.5- 1 6 Servicing the Control Board
1.
Timer
Set the HP
RCL
P ER
2.
Output
3. Check U26 pin 3 for a 100 Hz signal.
Check the TIRE signal on
81 12A
0
as follows:
10
µs
U26
Enabled
pin 4 is HIGH.