Service Guide 5-17
8719ET/20ET/22ET Power Supply Troubleshooting
8719ES/20ES/22ES Error Messages
RF Network Analyzers
Error Messages
Three error messages are associated with the power supplies functional group. They are
shown here.
• POWER SUPPLY SHUT DOWN!
One or more supplies on the A8 post regulator assembly is shut down due to one of the
following conditions: overcurrent, overvoltage, or undervoltage. Refer to “If the Green
LEDs of the Post Regulator (A8) Are Not All ON” on page 5-13.
• POWER SUPPLY HOT!
The temperature sensors on the post regulator (A8) assembly detect an
overtemperature condition. The regulated power supplies on A8 have been shut down.
Check the temperature of the operating environment; it should not be greater than
+55 °C (131 °F). The fan should be operating and there should be at least 15 cm (6 in)
spacing behind and all around the analyzer to allow for proper ventilation.
Check the Fuses and Isolate A8
Check the fuses associated with each of these supplies near the A8 test points. If these
fuses keep burning out, a short exists. Try isolating A8 by removing it from the
motherboard connector, but keeping the cable A15W1 connected to A8J2. Connect a
jumper wire from A8TP2 to chassis ground. If either the +15 V or −12.6 V fuse blows, or the
associated green LEDs do not light, replace A8.
If the +15 V and −12.6 V green LEDs light, troubleshoot for a short between the
motherboard connector pins XA8P2 pins 6 and 36 (−12.6 V) and the front panel probe
power connectors. Also check between motherboard connector pins XA8P2 pins 4 and 34
(+15 V) and the front-panel probe power connectors.
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