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Troubleshooting
Introduction
6-6 Agilent E4418B/E4419B Service Guide
A
Select
Preset/local
Confirm
Lower Window - using
Meas/Setup
Limits
Limits On
TTL Output
TTL Output On, Fail O/P Low
Yes
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 42
and Rmt I/O connector pin 4.
Yes
No Fault found with Upper
Window TTL Over Limit
detection circuit - check user
application/implementation
DVM reading
5.0V+/-0.5V?
DVM reading
0.0V+/-0.5V?
YesNo
End
A4 Comms Assy
Defective
A2 Processor Assy
Defective
No
Select
Fail O/P High
DVM reading
450Ω +/- 10%
No