Service Manual

3-4
n
18” & 24” ADA Built-In Dishwashers
TESTING
For Service Technician Use Only
General Theory of Operaon
Refer to Wiring Diagram on page 3-3.
Neutral and L1 (AC voltage) enters the Control Board at
CON1, pins 1 & 2 respecvely. AC is converted to DC voltage
at the Low Volts Power Supply (LVPS). Supplies include +12
and +5 VDC, and DC GND (REF). These low voltage supplies
are used to provide power to the microprocessors and board
components, power the sensors and energize the AC relays.
The 12 VDC is vital to the operaon of the dishwasher.
This supply is necessary to operate all 120 VAC loads in
the dishwasher, whether they are connected to a relay or
controlled by TRIACs. 12 VDC is generated by the power supply
and ows through the door switch—when closed—to be
available to the heater relay, wash motor relays, and the drain
pump relay. A relay coil becomes energized when the control
closes the LV drive circuit for a specic relay compleng 12V
pathway, which in turn closes the relay switch providing AC to
the load.
Power Check
This test checks for incoming and outgoing power to and from
the control board. This test assumes that proper voltages is
present at the outlet or direct connect cable.
Test Procedure
1. Unplug dishwasher or disconnect power.
2. Remove access panel.
3. Remove terminal box cover.
4. With a voltmeter set to AC, insert black probe inside white
wire screw nut (N) and insert red probe inside black wire
screw nut (L1).
5. Plug in dishwasher or reconnect power.
¾ If 120 VAC is present, unplug dishwasher or disconnect
power and proceed to step 6.
¾ If 120 VAC is not present, have customer correct power
problem at outlet or breaker.
6. Remove the control board cover.
7. Locate connector CON 1.
8. With a voltmeter set to AC, connect leads across the two
pins (“N” and “L”) on CON 1.
9. Plug in dishwasher or reconnect power.
¾ If 120 VAC is present, go to step 10.
¾ If 120 VAC is not present, check for open connecon
between terminal block and control. Repair as needed.
10. Verify DC Supplies
• 5 VDC is used to power IC’s and micro-processors on the
circuit board as well as provide power to the sensors.
¾ If 5 VDC were missing, the control and Turbidity Sensor
would not funcon. To verify 5V ± 5%, with a voltmeter
set to DC, connect the black lead to CN4-2 (DC GND)
and the red lead to CN3-1 (+5V).
• 12 VDC is used to actuate the heater, drain and wash pump
relays as well as the dispenser and water inlet valve.
¾ If 12 VDC was missing, the heater, pumps, and all other
loads would not turn on. To verify 12V ± 5%, with a
voltmeter set to DC, connect the red lead to CN6-1
(12V) and black lead to CN4-2 (DC GND).
Troubleshoong Missing DC Supplies: Refer to the
wiring diagram on page 3-4 when troubleshoong the
DC supplies. If 5 VDC or 12 VDC is missing on the control,
unplug dishwasher or disconnect power, and then
disconnect all components/loads from the control relying
on the missing or loaded supply. Plug in dishwasher or
reconnect power and check if the DC supply has returned.
¾ If not, replace the control.
¾ If it has, turn o dishwasher and reconnect one
connector at a me unl the component loading down
that supply has been idened.
11. Unplug dishwasher or disconnect power.
12. Reassemble all parts and panels.
DANGER
Electrical Shock Hazard
Only authorized technicians should perform
diagnostic voltage measurements.
After performing voltage measurements,
disconnect power before servicing.
Failure to follow these instructions can result in
death or electrical shock.