Control Board Information; Fuse Service & Resistance Checks; Component Testing - Maytag MDB series Service Manual

TESTING
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.

Control Board Information

SPECIFICATIONS
ELECTRICAL SUPPLY:
(Under Load): 60Hz 120V AC
SUPPLY WATER FLOW RATE:
To fill 2 qt (1.9 L) in 27 seconds, 120 psi maximum, 20 psi
minimum.
SUPPLY WATER TEMPERATURE:
120°F (49°C) (Before starting a cycle, run water from sink
faucet until hot.)
WATER CHARGE:
1.58 gal. (6.0 L) Approximate
LOWER SPRAY ARM ROTATION:
12 TO 40 rpm
UPPER SPRAY ARM ROTATION:
12 TO 30 rpm
3-4 Maytag Chopper Dishwashers
n
For Service Technician Use Only
Fuse Service & Resistance Check
F9 = SMALL-TRIAC LOAD FUSE
Check operation of loads during the Service Diagnostics cycle.
¾ If any of the TRIAC loads work, F9 Fuse is OK.
¾ If all TRIAC loads fail to work, F9 Fuse could be open. See
Fuse Resistance Check."
FUSE RESISTANCE CHECK:
1. Unplug the dishwasher or disconnect power.
2. Measure resistance of F9 Fuse.
NOTE: Fuses are on the bottom of the Control Board but
can be checked from the top side. See "Control Pinout"
diagram.
¾ If resistance is < 3 Ω, then fuse is OK.
¾ If resistance is > 3 Ω, then fuse is open.
IF THE FUSE IS OPEN:
Inspect and check resistance of all loads on fuse. If any loads
are open, shorted, or have evidence of overheating or pinched
wires, replace loads and/or repair wires.

Component Testing

TESTING DISHWASHER COMPONENTS FROM THE
CONTROL
Before testing any of the components, perform the following
checks:
• The most common cause for misdiagnosed control
failure is poor connections. Therefore, disconnecting,
inspecting and reconnecting wires will be necessary
throughout test procedures.
• All tests/checks should be made with a VOM or DVM
having a sensitivity of 20,000 ohms-per-volt DC, or
greater.
• Check all connections before replacing components,
looking for broken or loose wires, failed terminals, or
wires not pressed into connectors far enough.
• Voltage checks must be made with all connectors
attached to the boards.
• Resistance checks must be made with power cord
unplugged or power disconnected, and with wiring
harness or connectors disconnected from the control.
• The testing procedures in this section may require the
use of needle probes to measure voltage. Failure to use
needle probes will damage the connectors.