Start Circuit; Fill Circuit - Dexter Laundry T-350 Parts & Service Manual

Electrical Path Circuit Schematics

Start Circuit

Power travels into the machine on L1 & L2 & (L3, if 3 phase used). L1 and L2 provide 208- 240VAC to the
controls transformer which steps the voltage down to 24VAC for the controls. (The L1 connection at the
controls transformer must be checked at start-up to coincide with machine operating voltage) The 24VAC
travels out from the transformer on either [X-1 red wire directly to the 1.5 amp fuse] or [X-1 black/red wire
to TB-4 and then through the red wire to the 7 amp fuse. The controls transformer also creates a neutral
on the X-2 black/blue wire that connects to TB-1. From the fuse holder, 24VAC travels on the red wire to
the #6 terminal on the terminal strip and then through the black wire to another step-down transformer.
From the terminal strip the blue wire will provide the neutral for gear motor, thermoactuators, and all
valves. The white wire provides the neutral from the terminal to the step down transformer.
24VAC is stepped down to 2.3VAC (blue wires), 24VAC (red wires), and a yellow center tap wire to the P-7
power connection on the main controller PCB . With the main control PCB now powered, 26.8 VDC goes
out on the black wire of the P-4 connection from the main control PCB to the S5 door closed switch which
mounted on the hinge side. Closing the door will engage the door closed switches, sending the voltage to
the red wire on the S1 door latched switch. Turning the door handle to the vertical latched position closes
the S1 door latched switch, returning the voltage to the main control PCB on the white/red wire at the P-4
connection. 26.8VDC is now present at the S2 and S3 door locked switches.
26.8VDC is also at the black and white wires between P-21 at the main control PCB and the P-20 of the
relay PCB. This voltage signals the relay PCB that the door is closed and latched making 24VAC available
to the relays controlling the door lock gear motor, drain valve, and water valves. Pressing the start button
on the front of the main control PCB signals the relay PCB to lock the door and 24VAC will go to the door
lock gear motor on the white/red wire from the P17 connector of the relay PCB. The door lock gear motor
engages and pulls up on the door locking rod, locking the door and closing the S2 and S3 door locking
switches.
The S2 locking switch is a backup to the S1 latching switch so that once the cycle starts the S1 isn't criti-
cal. The S3 locking switch provides 26.8VDC on the orange wire back to P4 connector at the main control
PCB and the P15 connector at the relay PCB. This signals that the loading door is closed, locked and safe
to continue wash operations. This activates the P-13 and P-14 yellow enable wires to the inverter drive to
allow motion. If there is no signal on P-15 (orange wire) their will be no motion of the tub. S1, S2, S3 and
S5 door switches are now closed . The green On LED and the door lock solenoid (discussed in start circuit)
will remain on throughout the cycle.
Fill Circuit-Warm
The relay PCB supplies 24VAC to the brown/yellow wire from P-17 to the drain valve which closes the
valve. The lock thermoactuator also receives 24VAC on orange/blue from P17 of the relay PCB. This device
prevents the door lock gear motor from dropping out and unlocking during the cycle in the event of a
power loss. The 24VAC will cycle on and off keeping the lock thermoactuator engaged until 70 seconds
before the end of the cycle. The main control PCB sends data commands to the VFD through the data
cable connected at P-6. These commands control the wash basket which will tumble one direction for 12
seconds, pause, and then reverse direction for 12 seconds.
The prewash or wash LED will illuminate at this time, powered through the white wires from the P-3 con-
nection of the main control PCB to the LED printed circuit board. Using the factory preset cycle as an
example: The washer fills the tub through the back of the machine with either one or both the C1 cold
and H1 hot water valves. From the P19 connection of main relay PCB, 24VAC is sent out on the white/
brown wire to the C1 cold water fill valve and the red wire to the H1 hot water fill valve depending on the
temperature selected. After a 90 second delay from the beginning of the wash cycle bath only, the deter-
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Part # 8533-104-001 1/18