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5725A
Instruction Manual
7-6
7-4. Manual Tests for Fault Isolation
Warning
The following servicing is to be done by qualified service
personnel only. To avoid electrical shock, do not service the
5725A unless you are qualified to do so.
Follow the access procedures and warnings in section 6 to
open the 5725A covers.
The voltage output transistor heat sinks are at lethal voltage
potential in ac v standby and ac v operate modes during normal
operation, and possibly in any other mode after a failure. The
heat sinks are exposed when any assembly is in the service
position, and when the heat sink cover is removed.
Use only non-conductive tools, and keep one hand behind your
back to avoid making a circuit through your body. If you work
on a 5725A with the power cord attached, and/or you are not
certain the high voltage has not bled off, do not wear a
grounded wrist strap. Wearing a strap increases risk of
dangerous electrical shock.
If self-diagnostics does not identify a faulty module, you can perform these manual tests.
Five different fault conditions are addressed. The following numbered list describes each
type of fault condition. Following that are troubleshooting tests to do for each type of
condition.
1. Fault at power-up (STANDBY and FAULT indicators lit).
2. Normal at power-up (STANDBY indicator ON), but trips out when trying to enter
voltage standby mode. (VOLTAGE MODE indicator momentarily lights, then
STANDBY and FAULT indicators light.)
3. Normal at power-up (STANDBY indicator ON) and ACV STANDBY (ACV and
STANDBY indicator ON), but trips out when trying to enter ACV OPERATE.
4. Normal at power-up, but trips out when entering current standby
5. Normal at power-up and CURRENT STANDBY, but trips out when entering current
operate.