Blank Display - Electrolux 30" Service Manual

If the potentiometers test good, remove and Ohm out
the harness. If the harness checks good, reinstall the
harness and replace one of the user interface boards
with a new or known good board. Turn one of the top
elements on. If the element operates normal, replace
the user interface board. If the F7 reappears, turn the
top element off, reinstall the board that was replaced
and replace the other user interface board. Turn one of
the top elements on. If the element operates normal
replace that user interface board. If the F7 still appears,
recheck the harness.

Blank display:

If the display remains blank when an element is turned
on, listen, if you hear a beep when the element is turned
on. If the range beeps, one of the user interface
board or the harness between the mother board and the
user interface boards is defective. Remove and Ohm
out the harness. If the harness checks good, reinstall
the harness and replace one of the user interface board
with a new or known good board. Turn one of the top
elements on. If the element operates normal replace
that user interface board. If the display remains blank,
turn the top element off, reinstall the board that was
replaced and replace the other user interface board. Turn
one of the top elements on. If the element operates
normal, replace that user interface board. If the display
remains blank, recheck the harness between the mother
board and the user interface boards. If you do not hear
the beep, replace the mother board.
Element not heating:
If an element or portion of an element does not heat but
the display shows the correct indication, either the mother
board, the element, or the element wiring is defective.
To determine which is defective:
1. Turn all surface element switches off.
2. Check the wiring diagram on the range to see which
terminal on the mother board is wired to that element
or portion of that element.
3. With a voltmeter measure the voltage drop between
that terminal and neutral on the mother board. If the
meter reads line to neutral voltage (120 VAC) the
mother board is defective. If the meter reads zero
the element or wiring to the element is defective.
4. Turn the switch to high, raise the cooktop, and
measure the voltage drop across the element. If the
meter reads line to line voltage (240 VAC) the
element is defective. If the meter reads zero the
wiring is bad.
Warm and serve zone:
The warm and serve zone circuit on smooth top ranges
uses a line to neutral (120 VAC) standard infinite switch,
a line to neutral (120 VAC) element with a built-in limiter
to protect the glass, and an indicator light.
L1
Element
L1
H1
Indicator light
Troubleshooting:
There are four ways a warming zone system with a stan-
dard 120 VAC infinite switch can fail:
1. The element does not heat.
2. The switch does not cycle the element off and on
when set to a position other than high.
3. The element operates correctly, but the indicator light
does not glow.
4. Indicator light glows with all the infinite switches
in the off position.
NOTE: If the indicator light glows very dimly with the
switches in the off position, this is caused by a capacitive
feed over in the wiring and can be corrected by connecting
a 100,000 Ohm 1/4 watt resistor in parallel with the light.
Element does not heat:
Checking the system with a Voltmeter, if the element
does not heat up:
1. Remove the back panel of the backguard to expose
the switch terminals.
2. With a Voltmeter set for AC on a scale higher than
120 Volts measure the voltage drop between
termnals L1 and L2. If the meter reads zero the
38
N
2A
1A
H2
L2