GE ZBD5900 Technical Service Manual page 22

4.5 GENERAL DIAGNOSIS - 5600 MODEL
To assist in diagnosis, each of the 60 timer control steps can
be manually advanced.
access knob are required to access manual advance opera-
tion. They are available as a tool kit (access tool and knob)
under the publication # 31-9022.
Prior to removing the timer control knob, advance the timer
control knob pointer to the twelve o'clock position, which is
the "OFF" position. The timer control knob can then be
removed by grasping the knob and pulling towards you.
To reinstall the timer control knob, align the four flutes of the
timer control shaft with the four slots in the timer control knob
and push the timer control knob onto the shaft securely.
NOTE: The nylon shaft of the timer control has three large
flutes positioned at twelve o'clock, three o'clock and six
o'clock. A smaller fourth flute is positioned at nine o'clock.
Identify the four slots in the timer control knob and index
accordingly to assist reinstallation to the timer control shaft.
Fit the timer access knob to the timer control shaft and insert
the timer access tool through the hole in the center of the
timer access knob. While pushing the timer access shaft in
towards the timer control, rotate the timer access knob until
the timer access shaft pushes in 1/2" further towards the
timer control as shown.
Each step of the timer control can be manually selected so
that the specific circuits are activated for diagnosis of the
circuit or associated components. When the diagnosis is
complete, remove the timer access shaft, rotate the timer
access knob to 12 o'clock, remove the timer access knob
A timer access tool and timer
Timer access tool
and replace with the timer control knob.
4.5.1 Operating Sequence
To start a program, the timer control knob is turned to the
start of a selected wash program. If the timer control knob is
turned past the selected cycle, then turned an additional full
turn to the start position of the selected cycle, the escape-
ment mechanism will advance the timer to the start of the
cycle.
NOTE: The INTERNAL RATCHET/GEARING will be audible,
however a pause of approximately one minute will occur
before any electrical components operate.
Ensure the Off/Normal/Normal+Heat/Boost/Boost+Heat is
set in one of the four "ON" selections. The control is the main
active supply into the dishwasher.
At the start of any program, the drain mode is energized to
ensure the tub is empty, prior to energizing the fill circuit.
The dishwasher is equipped with a fill time system, hence
the tub must be empty prior to a timed fill. A minimum drain
mode period of forty seconds will occur prior to a fill mode
on any program selected.
Reference to the electromechanical sequence chart (Section
6.1), determines the cam functions of the 60 steps/incre-
ments of the timer control. The wash temperature (°F) is
detailed in the right hand column with wash temperatures
listed for "Normal" and "Boost" .
It is not necessary to document the complete 60 steps/
increments since some of the functions are repeated in most
programs.
The complete "Rinse" program, consisting of steps/incre-
ments No. 3 to No. 7 will be covered in full detail in the
following text. A selection of the key steps/increments will
also be detailed to enable a technician to diagnose an
electrical or mechanical fault in conjunction with the following
wiring diagrams which have the active circuits highlighted in
bold lines.
The following data, applicable to the "Rinse" and other key
steps/increments (e.g. "Circulate & Heat"), provides a means
of checking a circuit for continuity by establishing if the
electric supply is available from one component to the next
component in the circuit.
E.g. if the pressure switch has electrical power available at
No. 1 terminal and not present at No. 2 terminal when it is
programmed to be present, this indicates either a faulty
pressure switch, or the pressure switch is sensing a satisfied
condition (i.e. continuity between terminal No. 1 and No. 3).
By following the components/circuit listings from one compo-
nent to the next in the line component diagrams, you will
identify the fault within the circuit.
applicable main circuits highlighted on the wiring diagram, to
enable each main circuit to be traced from the main terminal
to the relevant component. The timer sketch on the right
hand side of the circuit diagram shows which contacts are
energized for the particular step.
21
Each step has the