Keysight Technologies E4417A Service Manual page 124

Yes
No Fault found with Upper
Window TTL Over Limit
detection circuit - check user
application/implementation
Figure 6-2 Troubleshooting Guide - TTL Output 1 (continued)
Keysight E4416A/E4417A Power Meters Service Guide
Select
Preset/local
Confirm
Meas/Setup
Limits
Limits On
TTL Output
TTL Output On, Fail O/P Low
DVM reading
Yes
5.0V+/-0.5V?
Select
Fail O/P High
DVM reading
No
0.0V+/-0.5V?
A2 Processor Assy
A
Power down meter.
Disconnect ac power and battery if fitted.
Remove A2 Processor assy, as directed on page
5-9, to access the Comms Assembly connector.
Use DVM to check resistance between J4 pin 41
and Rmt I/O connector pin 3.
Yes
Defective
End
Troubleshooting
No
DVM reading
450Ω +/- 10%
A4 Comms Assy
Defective
6
No
131