Technician Service Guide 33367B
8
SECTION 3 - TRANSFORMER TESTING
PROCEDURE
DANGER: HAZARD OF ELECTRIC SHOCK!
THE FOLLOWING TESTS REQUIRE THE
CHARGER TO BE CONNECTED TO A LIVE AC
OUTLET. FOLLOW ALL ELECTRICAL SAFETY
PRECAUTIONS TO AVOID ELECTRIC SHOCK!
The transformer primary coil must be energized by
the AC voltage and frequency specified on the
charger nameplate in order to obtain accurate test
results. Verify the specified voltage is present at test
points A and B on the service wiring diagram, see
figure 3. If no voltage or an incorrect amount of
voltage is measured, testing of the AC circuit is
required before transformer testing can be
performed. Begin the AC circuit testing with
Inspect
and test for proper AC supply voltage at the
outlet.
Part A
Test for correct transformer output coil voltage.
Disconnect the AC power plug from the outlet and
the DC output plug from the equipment charging
receptacle. Remove the cover from the charger and
disconnect both transformer output coil leads from
the heatsink plates. For personal safety, make sure
the transformer leads are isolated and not making
contact with any components or the case of the
charger. Attach the test leads of a suitable AC
voltmeter to the transformer output coil leads, tests
points C and D on the service wiring diagram, see
figure 4. Reconnect the AC power plug to a live
outlet. Measure and record the AC voltage present
at the transformer output coil leads and compare to
the values in table 2.
Figure 4
If the measured AC voltage indicates the
transformer has failed, indicated by significantly
lower voltage readings, replace the transformer with
the replacement service part specified on the parts
list for the model charger being serviced.
Part B
Test for correct transformer auxiliary coil
voltage.
Disconnect the AC power plug from the outlet and
the DC output plug from the equipment charging
receptacle. Remove the cover from the charger.
Carefully remove the timer kit edge connector or flag
terminals attached to the DC sense leads of the
control cable from the electronic timer.
Before measuring the auxiliary coil output voltage,
inspect and test for continuity the transformer
auxiliary coil lead extensions. Also, inspect the
contacts in the edge connector for distortion,
corrosion or any condition that would prevent
electrical contact with the pads on the electronic
timer. Measure continuity of the transformer
auxiliary coil circuit by placing the test probes of a
continuity meter on pins 4 and 6 of the electronic
timer edge connector. If no continuity is measured
between the two points, rework or replace the
transformer extension leads, edge connector and/or
transformer, as needed.
Attach the test leads of a suitable AC voltmeter to
the auxiliary lead contacts in the edge connector,
pins 4 and 6 on the service wiring diagram. See
figure 5. Reconnect the AC power plug to a live
outlet. Measure and record the AC voltage present
at the specified edge connector pins and compare to
the values in table 2.
Figure 5
