HP 2040D User Manual
Page 34
Series 2040 Test System
Series 2040 Maintenance Manual V2.00
Diagnostics
33
FAULT LOOP
The Series 2040 Test System incorporates a “fault loop” for troubleshooting
and self-diagnostics. The cable between the UUT Power Supply Controller
and the Testhead, besides providing a path for the power supply output,
contains the fault loop. If the fault loop is broken, it will cause the controller
to shut down and report an error to the computer (the next time the computer
tries to give it a command). The fault loop is broken by the controller itself
whenever the controller detects an error. This signals to the other controllers
that they too should shut down. If a controller for a power supply channel is
unresponsive and the “Ext.Fault” LED on the Testhead Power Supply
Controller is on, a communication problem exists between the CPU and the
controller. If the LED is out, the fault loop is probably broken.
The power supplies may be isolated for diagnostics as shown in the following
pages. If a supply is isolated and fails to power up, it is most likely the
problem. If a supply is isolated and powers up, it can b eliminated as the
cause of the failure.