Maytag MAH5500BWW Service Manual - Page 117

START/PAUSE INPUT The start/pause input is selected on the membrane switch for both washers. If this input is initially selected the machine control will begin the wash cycle sequence as defined by the user input selections. If this input is selected when a cycle is in progress, the machine control will pause the cycle and unlock the door when it is safe to do so. (Note: Machine control board is powered up all the time. There no longer is a line relay used, as opposed to the MAH3000, 4000 and 5500A models.) TACH INPUT The tach input is a feedback signal from the motor control. It provides eight pulses per revolution of the switched reluctance motor. The motor runs at 14 times the speed of the spinner (14:1 belt ratio). The tach input is used for monitoring speed and out-of-balance detection (See Tachometer Circuit Diagnostics). If the machine control commands a motor speed and direction but does not sense a tach input signal within 2 or 3 seconds, it will assign a HELP code number and perform 10 retries. If unsuccessful, this generally indicates a locked rotor or a malfunction in the motor control. If the machine control commands a coast down from final spin speed but is still receiving a tach input signal after two minutes, it will log appropriate service codes. OUTPUT MODIFICATIONS DEFINED DOOR LOCK/UNLOCK SOLENOID OUTPUT The Door Lock/Unlock Solenoid Output signal is a 60 millisecond pulse sent to a solenoid in the door lock assembly. The solenoid is attached to a lever which moves a slider in the mechanism to lock the door after it has been closed and the cycle started. The solenoid has two coils, one for locking and one for unlocking when a pulse is directed to specific terminals on the solenoid. Power is not continuously applied to the solenoid, because this would damage the solenoid. END-OF-CYCLE SIGNAL OUTPUT The End-Of-Cycle Signal Output is an internal signal on the machine control between the microprocessor and annunciator. The end-of-cycle signal sounds when a wash cycle is finished. The end-of-cycle signal sounds as four pulses on the MAH5500B and 3 pulses on the MAH7500 in a 0.5 second intervals. If the door is opened right at the end of the cycle or during the end of cycle beeps, then the signal will stop on the MAH5500B only. If the start/pause key is pressed near the end of the cycle, the end of cycle signal will not occur unless the cycle is restarted and allowed to finish. If the Off key is pressed, the end of cycle signal will not occur. The end of cycle signal will occur when the door is unlocked and ready to open on the MAH5500B. On the MAH7500, the signal sounds then the door is unlocked. HEATER OUTPUT (LCD Washer only) The machine control board turns the heater on to heat the wash water during the main wash until the temperature reaches the targeted main wash temperature. The heater is turned back on at any point the temperature falls 5º F 16010486 (16008373-05) Revised 02/01 Section 2. Washer Controls Overview ©2001 Maytag Appliances Sales Company 2-5