28
Temco DV5200, DV6400 Series
77531
Troubleshooting
SIT Millivolt Valve
NOTE: Before troubleshooting the gas control system, be sure external shut off is in the “ON” position.
WARNING: Before doing any gas control service work, remove glass front!
Table 1
Valve Type
Main Operator
Safety Magnet
NOVA MV Plus
Minimum Voltage
145mV
Hold-in Current
Less than 285mA
Coil Resistance
2.25
Ω
±
0.5
Ω
Drop-out Current
Greater than 125mA
Coil Resistance
0.108
Ω
±
0.003
Ω
Problem
Possible Cause
Solution
Pilot will not light.
Air in gas lines.
Bleed all air from gas lines.
Defective spill switch.
Check for continuity across spill switch leads. Replace spill
switch if excessive resistance is present, or if circuit is
electricallyopen.
Wrong inlet pressure.
With the main burner functioning, adjust the inlet pressure
regulator to supply gas to the appliance within the design
parameters of the appliance manufacturer. (Typically 7”NG,
11”LPG).
Defective spark electrode.
Replace piezo wire if insulation is cracked or the tip is cor
roded.
Verify that the spark gap between the pilot and the electrode
is correct.
Defective piezo wire.
Replace piezo wire if insulation is damaged, or the wire is bro
ken or corroded.
Safety interlock function engaged.
Allow thermocouple to cool until the mv drops below the hold-
in requirements of the safety magnet, (30 seconds or less).
Re-light pilot.
Pilot will not hold.
Wrong inlet pressure
With the main burner functioning, adjust the inlet pressure
regulator to supply gas to the appliance within the design par
ameters of the appliance manufacturer. (Typically 7” NG, 11”
LPG)
Pilot adjustment screw not
After the pilot has been lit for approximtely three (3) minutes,
properly adjusted.
and only the thermo-generator wire connected to the main
operator head, measure the voltage across TPTH and TP.
this open circuit voltage should be between 500mV and
750mv. Tune the pilot adjustment scrw until the mV reading
falls within these parameters. (Counterclockwise increases
mV reading, clockwise decreases.
Thermocouple or thermogenerator
Make certain that the thermocouple and thermogenerator are
not properly inserted into the pilot
fully inserted and tightened into their receptacles in the pilot
housing.
head. The thermocouple should be threaded into the valve
hand-tight, plus 1/4 turn with a wrench.
Thermocouple or thermogenerator
With the thermocouple and thermogenerator tips cool, clean
has film build-up on tip.
the upper 3/8” with a very fine emery cloth.
Electrical resistance too high.
Using a very fine emery cloth, clean thermo-generator and
thermocouple connections at valve. Tighten thermocouple into
valve hand-tight, plus 1/4 turn with a wrench.
System Checks
