Lancaster 7-LX-100, Installation, Operating And Service Manual

PAGE 23

DRIVE CAP ASSEMBLY, MAIN PISTON AND REGENERANT PISTON

 (refer to pages 15 &16 for diagrams)

:

The drive assembly must be removed to access the drive cap assembly. The drive cap assembly must be removed to 

access the piston(s). The drive cap assembly is threaded into the control valve body and seals with an o-ring. To remove 

the drive cap assembly use the special plastic service spanner wrench (see page 19) or insert a ¼” to ½” flat blade 

screwdriver into one of the slots around the top 2” of the drive cap assembly so it engages the notches molded into the 

drive back plate around the top 2” of the piston cavity. See figure below. The notches are visible through the holes. Lever 

the screwdriver so the drive cap assembly turns counter clockwise. Once loosened unscrew the drive cap assembly by 

hand and pull straight out.

The drive cap assembly contains the drive cap, the main drive gear, drive cap spline, piston rod and various other parts 

that should not be dissembled in the field. The only replaceable part on the drive cap assembly is the o-ring. Attached to 

the drive cap assembly is the main piston and a regenerant piston.
The regenerant piston (the small diameter one behind the main piston) is removed from the main piston by pressing 

sideways and unsnapping it from its latch. Chemically clean in dilute sodium bisulfite or vinegar, or replace the regenerant 

piston if needed. To remove the main piston fully extend the piston rod and then unsnap the main piston from its latch by 

pressing on the side with the number. Chemically clean in dilute sodium bisulfite or vinegar, or replace the main piston.

Reattach the main piston to the drive cap assembly. Reattach the regenerant piston (if needed) to the main piston. 

Reinsert the drive cap assembly and piston into the spacer stack assembly and hand tighten the drive cap assembly. 

Continue to tighten the drive cap assembly using a screwdriver as a ratchet until the black o-ring on the spacer stack 

assembly is no longer visible through the drain port. Excessive force can break the notches molded into the drive back 

plate. Make certain that the main drive gear still turns freely. The exact position of the piston is not important as long as 

the main drive gear turns freely.
Reattach the drive assembly to the control valve and connect all plugs. After completing any valve maintenance involving 

the drive assembly or the drive cap assembly and pistons, unplug power source jack from the printed circuit board (black 
wire) and plug back in or press and hold 

NEXT

 and 

REGEN

 buttons for 3 seconds.

This resets the electronics and establishes the service piston position. The display should flash the software version and 

then reset the valve to the service position.

REFILL FLOW CONTROL ASSEMBLY

 (refer to page 17 for diagrams)

:

To clean or replace the refill flow control, pull out the elbow-locking clip and then pull straight up on the elbow. Replace the 

elbow locking clip in the slot so that it is not misplaced. Twist to remove the white flow control retainer. The flow control 

can be removed by prying upward through the side slots of the retainer with a small flat blade screwdriver. 
Chemically clean the flow control or the white flow control retainer using dilute sodium bisulfite or vinegar. Do not use a 

wire brush. If necessary, replace the flow control, o-ring on the flow control retainer, or the o-ring on the elbow.
Reset the flow control so the rounded end is visible in the flow control. Reset the white flow control retainer by pushing the 

retainer into the elbow until the o-ring seats. Remove locking clip, push down on elbow to reset and insert locking clip. 

Do not use Vaseline, oils, or other unacceptable lubricants on o-rings. A silicone lubricant may be used on the o-ring on 

the elbow or the white retainer.