CHAMPION USN72 - Manual (Page 59)

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Part 5: BASIC SERVICE
5.3 Component Repair and Replacement (Cont.)
5.3.2 Water Line Strainers
There are two water line strainers on the USN-72 dishwasher. The first strainer is located on the
3/4" main water line to the booster. The second is located on the incoming water line for the tank
fill. The line strainer screen may become clogged with debris. To clean the strainer screen: Turn
off the main water supply valves. Open the tank fill manual valves to bleed off pressure. Run a
dishrack through the machine to operate the final rinse and bleed off water pressure at the booster.
Turn power off at the dishwasher control cabinet. Remove the locknut at the end of each strainer
"Y." Remove the strainer screen and flush clean with water. Reinstall in reverse order. Turn on
water supplies and check for leaks.
5.3.3 Vacuum Breaker Repair
Vacuum Breakers are located at the top of the USN-72 in the 3/4" final rinse water
line and each of the 1/2" tank fill lines. They prevent the siphoning of dish-
machine water back into the potable water supply. Each vacuum breaker contains
a moveable float. To replace the float: Turn off the main water supplies. Turn off
the power at the dishwasher control switch. Unscrew the top of the vacuum
breaker. Remove the float. Inspect the interior of the vacuum breaker. Remove
any mineral deposits and inspect the float seating surfaces for pitting. (If badly pitted, replace the
entire vacuum breaker assembly). Install a new float repair kit and reassemble in reverse order.
Turn on power and water supplies. Operate the dishwasher and check for leaks.
5.3.4 Water Solenoid Valve Repair
A 3/4" water solenoid is located in the final rinse water line at the
outlet of the final rinse booster. The valve is controlled by the opera-
tion of the final rinse switch assembly which connects 120VAC to the
valve coil during a final rinse operation. If the valve fails to operate,
first check that 120VAC is supplied to the valve coil. If voltage is not
present, then refer to the electrical schematic and troubleshoot the
circuit. If voltage is present then the valve may require a rebuild kit or
replacement coil. Turn off power at the dishwasher power switch and
main disconnect. Turn off main incoming water supply and bleed off
any water pressure in the line. Check the coil for continuity with a VOM set at the highest
resistance range. If the coil checks good then disassemble the valve by unscrewing the threaded
bonnet with a strap or spanner wrench. Remove and inspect the valve piston and diaphragm.
Inspect the valve seat for mineral deposits and pitting. (Replace the complete valve assembly if
pitting is severe). Reassemble the valve in reverse order. Turn on power and water supplies and
check for leaks.