Wayne SC80 User Manual - page 18
18
PRELIMINARY CHECKS, DIAGNOSIS AND SERVICE HINTS
Although the following tests can be made using standard volt meter, it is quicker and more convenient to use a Fenwal
Model 05-125539-001 Test Adapters.
1. Input Polarity
If a spark is present and the gas valve opens for the flame establishing period but the control locks without sensing
flame, check the input voltage at terminals 1 and 6 for the proper polarity. Terminal TH or 24V should be “hot”; 24VAC
(05-16) with respect to ground. Terminal GND is neutral, or zero voltage, with respect to ground.
2. Improper Grounding
If a flame is present during the Trial for Ignition period but the system shuts down, ensure that the burner is properly
grounded. If the burner is not grounded, the flame monitoring signal will not function and the system will go into
lockout. Check for loose or corroded terminals and replace if necessary. Ensure good electric connection by scraping
paint or any other foreign matter off the area where ground connection is made.
It is equally important to be certain that the electrode bracket assembly is properly grounded. The bracket should be
common with the ground lead on the input connector (ground terminal 6). If the bracket is not properly grounded,
damage to the ignitor can result.
3. Inoperative High Voltage
If there is no spark or sparking is intermittent, check the following after disconnecting voltage to the system.
a. Check spark gap. Reference Flame Rod and Spark Electrode drawings later in this section and ensure the gaps
are correct.
CAUTION:
NEVER REPLACE THE COMPONENT BOARD WITHOUT FIRST CHECKING TO ENSURE THAT THE
ELECTRODE HAS THE PROPER GAP. IF THE GAP IS TOO WIDE, DAMAGE TO THE IGNITOR CAN RESULT.
b.
Check electrode leads and determine there is no corrosion at the terminals. If there is corrosion, clean it off.
DO
NOT USE LIQUIDS TO CLEAN TERMINALS.
Use steel wool or emery cloth to clean.
c. Check ceramic insulators for cracks, foreign matter, and carbon. If there are cracks, replace electrodes. If there is
carbon or foreign matter, clean it off.
DO NOT USE LIQUIDS TO CLEAN.
Use steel wool or emery cloth to clean.
d. Check high voltage lead wire for cracks or breaks. If there are cracks, breaks or chafing, replace high voltage
wire.
e. Check to ensure that the high voltage terminal is clear of dust, moisture or any foreign matter that could create
high voltage leakage to ground.
4. Valve Malfunction
With power applied to the ignitor, sparking should occur and the gas valve should open simultaneously. If sparking
occurs but the valve does not open, place a volt meter between the Valve terminal on the ignition control and ground
(or across valve). If valve does not function with voltage, it should be replaced. If the voltage is not present across
Valve terminal and ground (or across valve), the control should be replaced.
5. Electrode Placement
a. Electrode should be placed so optimum flame current is achieved for proper application.
b. Flame should not impinge on any portion of ceramic insulator.
6. Flame Current
The flame detector circuit uses the ionized gas flame to conduct the flame signal. This signal is a small DC current
which can be measured directly with a 0 to 50 microamp meter.
Typical flame current readings with the Wayne control range from .4-.8 µA. Although this control is able to sense
flame with a signal as low as .1 µA, we recommend replacing the electrode assembly if the signal is .1 µA or less in
order to avoid future nuisance lockouts.
To measure flame current, first shut off the power to the system and then connect a DC micro amp meter between the
blue flame sense wire and the terminal marked “SENSE” on the ignition control. Light the burner. If the meter reads
below zero, shut the system off and reverse the meter leads.