Service manual

Service Manual
Appendix E - DC insulation testing - class 1
UK information only
Equipment required
A portable appliance tester or an insulation tester that
provides 500V DC ONLY.
Note that the computer contains RFI capacitors on the
PSU input.
It is recommended that the calibration and operation of
the instrument be checked frequently enough to ensure
its accuracy.
DANGER
THE FOLLOWING TEST INVOLVES HIGH
VOLTAGES. ALL NECESSARY PRECAUTIONS
MUST BE TAKEN TO ENSURE OPERATOR SAFETY
DURING TESTING. NOTE THAT THE OPERATOR
MUST BE TRAINED AND COMPETENT.
WARNING
SWITCH OFF THE COMPUTER, DISCONNECT IT
FROM THE MAINS SUPPLY, AND DISCONNECT
ANY EXTERNAL PERIPHERALS AND EXTERNAL
CONNECTIONS BEFORE CARRYING OUT THIS
TEST.
Before testing
Check the mains lead and plug for any physical damage
and replace if necessary.
Test Procedure
Consult the instructions supplied with the test equipment.
The test should be performed on a fully assembled
computer.
1 Insert the mains lead of the computer either into a
portable appliance tester, or into an adaptor, as shown
below.
2 Move the computer's power switch to the ON position.
3 Apply the test voltage for 1 (ONE) MINUTE and then
measure the resistance.
4 Pass level: GREATER than 2 (TWO) MOhm
5 Move the computer's power switch to the OFF position
and remove the mains lead from the portable
appliance tester.
Testing with an insulation tester
Mains lead Modified mains
socket - fully
enclosed and
securely mounted
Appendix E - DC insulation testing - class 1 Issue 2, June 1991 E-1