Lester 24EL8 Service Instructions

DUAL MODE BATTERY CHARGER

TECHNICIAN DIAGNOSTIC AND SERVICE INSTRUCTIONS

To discourage end users from disassembling the
charger, UNDERWRITERS LABORATORIES and
CANADIAN STANDARDS ASSOCIATION require
that the internal replaceable fuses be omitted from the
Owners Manual wiring diagram and parts list. Those
parts are included in the enclosed service wiring
diagrams and parts lists.
Refer to the Owners Manual for installation, normal
operating procedures, and safety precautions.
FOLLOW ALL SAFETY PRECAUTIONS.

DUAL MODE CHARGER TEST PROCEDURES

Disconnect both the AC and DC charger cordsets.
Remove the screws on each side of the charger and
lift the cover off. Refer to the Service Parts List and
compare to the charger under test to locate the
described test points. Make sure that all the charger
internal connections are secure and tight.
TEST FOR CORRECT AC VOLTAGE AVAILABLE
AT TRANSFORMER
Connect the AC cord to a live outlet; move the power
switch to AUTO. Verify that AC line voltage is
measured across terminals P-P on the transformer
(110-127 for 120 VAC models; 215-245 for 230 VAC
models).
TEST FOR CORRECT AC VOLTAGE AT
TRANSFORMER AUXILIARY COIL
Verify that approximately 26-30 VAC is measured
across terminals 1-3 on the transformer. Unplug the
electronic timer assembly and verify this same
voltage across the control cable assembly electronic
timer edge connector contacts 4-6.
One half of this measured AC voltage should appear
across transformer terminals 2-1 and 2-3. With the
electronic timer assembly unplugged, the same
reading should also appear across plug contacts 3-4
and 3-6, and 7-4 and 7-6, as well as 9-4 and 9-6.
Operating Instructions
TYPE 24EL8
TEST FOR CORRECT AC VOLTAGE AT
TRANSFORMER SECONDARY
Verify that approximately 58-64 VAC is measured
across transformer secondary terminals 4-7. Half of
this measured AC voltage should also appear across
the transformer coil center tap and each end,
transformer terminals 5-7 and 5-4, as well as 6-7 and
6-4.
Transformer failure is indicated when the measured
AC voltages are significantly lower than specified.
TEST FOR COMPLETE CIRCUIT FROM CHARGER
TO WHEELCHAIR BATTERIES IN THE
WHEELCHAIR
Move the power switch to OFF and unplug the AC
power cord and connect the charger DC output plug
to the charging receptacle of the wheelchair under
test.
Remove covers from wheelchair battery box and
measure battery system voltage at the battery
terminals inside the battery box, about 24 VDC.
Make sure this same battery pack voltage, about 24
VDC, is measured across where the RED lead from
the thyristor assembly connects to the ammeter
(+, POSITIVE), and transformer terminal 5 as well as
terminal 6 (-, NEGATIVE).
diagram.
IF THE CORRECT BATTERY VOLTAGE DOES
NOT APPEAR INSIDE THE CHARGER, THEN
TEST ALL CIRCUITS UNTIL THE OPEN CIRCUIT
IS ELIMINATED.
Repair or replace: Wheelchair charging circuit wiring,
or
fuseholders, or wheelchair charging circuit breakers,
or wheelchair charging receptacle.
cordset with charging plug, or charger DC fuse and/or
fuseholders. Charger control cable assembly if shunt
resistor tests as an open circuit, or charger ammeter if
1
wheelchair charging
Refer to the wiring
circuit fuses and/or
Charger DC
01004C