Troubleshooting Tests - Maytag MGD6500MBK Technical Manual

TROUBLESHOOTING TESTS

IMPORTANT: The following procedures may require the use of needle probes
to measure voltage. Failure to use needle probes will damage the connectors.
TEST #1: ACU Power Check
This test is used to determine if power is present at the machine control
electronics. This test assumes that proper voltage is present at the outlet.
1. Verify that the green LED on the ACU is lit and blinking when the dryer is
turned on.
2. Unplug dryer or disconnect power.
3. Check for appropriate line voltage at the outlet: 240 VAC
(electric 2-phase), 208 VAC(electric 3-phase), or 120 VAC (gas).
➢ If line voltage is present, go to step 4.
➢ If line voltage is not present, check for tripped circuit breaker or blown
household fuse. If CB (circuit breaker) is not tripped, have customer
check with qualified electrician.
4. Remove console to access the machine electronics.
5. ACU VAC – With voltmeter set to AC, connect black probe to ACU
J7-4 (N) and red probe to J7-3 (L1). (See Figure 1.) Plug in dryer or
reconnect power.
➢ If 120 VAC is present, unplug dryer or disconnect power and go to
step 6.
➢ If 120 VAC is not present, unplug dryer or disconnect power and perform
TEST #2: Supply Connections,
6. ACU +5 VDC – With voltmeter set to DC, unplug connector J2 from the
ACU and connect black probe to ACU J2-4 (ground) and red probe to
J2-2 (+5 VDC). Plug in dryer or reconnect power.
➢ If +5 VDC is present, unplug dryer or disconnect power and go to
step 9.
➢ If +5 VDC is not present, go to step 7.
18
FOR SERVICE TECHNICIAN'S USE ONLY
page 19.
2 J – W N I B U S ( + 5 V D C
and +12.7 VDC)
J2-1 RD +12.7 VDC
J2-2 NC +5 VDC
J2
J2-3 YL DATA
1 2 3 4 5
J2-4 BK GND
J2-5 NC
J7
4
J7-4 WH NEUTRAL
5
J7-5 TN DOOR SWITCH
6
J7-6 YL MYST VALVE
(STEAM MODELS ONLY)
K6
Steam Valve
Label
Relay
J4
Figure 1 - ACU Connectors and Pinouts
7. Unplug dryer or disconnect power. Unplug J4 from the ACU. Plug in
dryer or reconnect power and repeat step 6.
➢ If +5 VDC returns, the thermistor has shorted. To diagnose
thermistor,see TEST #4a,
➢ If +5 VDC is not present, go to step 8.
8. Unplug dryer or disconnect power. Reconnect J4 to the ACU and unplug
J2 from the ACU. Plug in dryer or reconnect power and repeat step 6.
Perform voltage check inside header J2 on ACU, between
pins 2 & 4—DO NOT SHORT PINS TOGETHER.
➢ If +5 VDC is still missing, unplug dryer or disconnect power and replace
the ACU.
➢ If +5 VDC returns, unplug dryer or disconnect power and check
harnesses and connections between the ACU and HMI. If acceptable,
replace the HMI.
9. ACU +12 VDC – with voltmeter set to DC, connect black probe to
ACU J2-4 (ground) and red probe to J2-1 (+12 VDC). Plug in dryer or
reconnect power.
➢ If +12 VDC is present, go to step 11.
➢ If +12 VDC is not present, go to step 10.
10. Unplug dryer or disconnect power. Unplug connector J2 from the ACU.
Perform voltage check inside heater J2 on ACU, between pins 1 & 4 -
DO NOT SHORT PINS TOGETHER.
➢ If +12.7 VDC is still missing, unplug dryer or disconnect power and
replace the ACU.
➢ If +12.7 VDC returns, unplug dryer or disconnect power and check
harnesses and connections between the ACU and HMI. If acceptable,
replace the HMI.
11. Unplug dryer or disconnect power.
12. Reassemble all parts and panels.
13. Perform steps under "Service Test Mode",
J4 – THERMISTORS
J4
1 2 3 4
J13 – MOISTURE SENSOR
J13-1 BK
J13
1 2
J13-2 RD
J7 – DOOR SWITCH/LOADS/L1
J7-1 LB MOTOR
1
J7-2 NC
2
J7-3 BK L1
3
Motor Relay
J7
Heater/Gas Valve - VT
Heater/Gas Valve Relay
K3
(Gas & Electric)
K2
J2
page 22.
page
J4-1 RD/WH OUTLET THERMISTOR
J4-2 OUTLET THERMISTOR
RD/WH
J4-3 OPEN
NC
J4-4 NC OPEN
MOISTURE SENSOR
MOISTURE SENSOR
L1-BK
J13
= Pin 1
12, to verify repair.