HP 4262A Operating And Service Manual page 202

Model 4262A
8-53. PRODUCT SAFETY CHECKS.
8-54.
WARNING
WHENEVER IT APPEARS LIKELY
THAT SAFETY PROTECTIVE PRO-
VISIONS HAVE BEEN IMPAIRED,
THE APPARATUS SHALL BE MADE
INOPERATIVE AND BE SECURED
AGAINST ANY UNINTENDED OPER-
ATION, THE PROTECTION IS
LIKELY TO BE COMPROMISED IF,
FOR EXAMPLE:
-- THE APPARATUS SHOWS VISI-
BLE DAMAGE.
-- THE INSTRUMENT FAILS TO
PERFORM THE INTENDED MEAS-
UREMENT.
-- THE UNIT HAS UNDERGONE PRO-
LONGED STORAGE UNDER UN-
FAVORABLE CONDITIONS.
-- THEINSTRUMENT HAS SUFFERED
SEVERE TRANSPORT STRESS.
The following five checks are recommended
to verify the product safety of the 4262A LCR Meter
(these checks may also be done to check for product
safety after troubleshooting and repair). When such
checks are needed, perform the following:
1,
Visually inspect interior of instrument for any
signs of abnormal, internally generated heat,
such as discolored printed circuit boards or
components, damaged insulation, or evidence
of arcing. Determine and remedy cause of any
such condition.
Using a suitable ohmmeter, check resistance
from instrument enclosure to ground pin on
power cord plug. The reading must be less
than 0.5 ohm. Flex the power cord while
making this measurement to determine whether
intermittent discontinuities exist.
Check GUARD terminal on front panel using
procedure (2).
Disconnect instrument from power sSource.
Turn power switch to on. Check resistance
from instrument enciosure to line and neutral
(tied together). The minimum acceptable re-
sistance is two megohms. Replace anycom-
ponent which fails or causes a failure.
Check line fuse to verify that a correctly
rated fuse is installed.
Section VIII
Paragraphs 8-53 and 8-54
8-29