Midco International Inc.
13
8470 70
Trouble Chart
6. Open the charging door, make sure any door open interlock is
temporarily by-passed and repeat trial for ignition.
a. Open main manual shut-off valve. With main fl ame present,
close charging door, remove temporary door open interlock
and check incineration chamber pressure. Burner peep hole
can be used for access to obtain approximate reading
(See Figure 3). Make sure sensing tube extends into the
incineration chamber at least 6″. Pressure should be
between 0″ to minus 0.5″ W.C. for J81A, 0″ to minus 1.0″
W.C. for J121A. If pressure is on the high negative side of
the range, increase the ignitor fl ame gas pressure to 4.0″ to
5.0″ W.C.
b. No fl ame present, clean and reset electrode assembly per
Figure 5 and repeat Step 6a.
A. With motor running, confi rm 120 volts as follows:
1. Between strip terminals L1 and L2: 120 volts present, voltage
OK.
2. Between strip terminals L1 and ground: 120 volts present,
ground OK.
3. Between strip terminals L2 and ground: No voltage, neutral
OK.
B. Follow test procedure as specifi ed in Step 2A.
1. Disconnect fl ame electrode wire and check for continuity.
2. Connect DC voltmeter in test jack in amplifi er. With ignitor
fl ame on, reading should be at 2 or more volts DC and steady.
Adjust ignitor gas pressure to obtain acceptable signal and
note gas pressure and signal strength for future reference.
C. If all checks listed above were satisfactory and the ignitor will not
stay lit, fl ame safeguard defective.
A. Confi rm 120 volts between strip terminal L2 and 8.
1. 120 volts present, continue with Step B.
2. No voltage, fl ame safeguard defective.
B. Connect manometer to main automatic valve downstream
pressure tap.
1. No gas pressure when valve is energized.
a. Confi rm that pressure of at least 5.5″ W.C. NATURAL,
8.0″ W.C. PROPANE, is available at the inlet of the main
automatic valve.
b. Pressure at inlet side OK, main automatic valve defective.
A. Low gas pressure.
B. Air shutter open too far.
C. Input adjuster not set properly.
A. High gas pressure.
B. Air shutter closed too far.
C. Insuffi cient free air in incineration chamber.
D. Dirty blower wheel.
E. Input adjustor open too far for air shutter setting.
A. Main automatic and/or ignitor gas valve defective.
B. High gas pressure.
3 Ignitor Flame on Only
During the 4 or 10
Second Trial for Ignition
4 Ignitor Lights But No
Main
fl
ame
5 Short Main Flame
6 Long Hazy Main Flame
7 Gas Fails to Shut O
ff
Trouble Chart
Continued
2 Motor Runs
Continuously But No Flame
and Burner Housing Cool
Continued
