AADCO 737 Series Operating Instructions Manual page 38

(d) If the fuse blows when the POWER switch is on, disconnect the power
cord
3.23 (d) Continued.
at the cooling fan, Figures 5, 6 and 11 (28). REMOVE POWER CORD
FROM WALL OUTLET and replace fuse. Reconnect power cord and
depress POWER switch to on position. If the fuse blows, the POWER
switch is defective and must be replaced. If the fuse does not blow, the
cooling fan is shorted. Replace fan.
13.24 If the fuse does not blow in (d) above, the problem is the methane reactor.
(a) Check resistance between chassis and white and black wires leading to
the methane reactor. If resistance is infinite, methane reactor wiring okay.
Replace fuse. REMOVE POWER CORD FROM WALL OUTLET WHEN
CHECKING FUSES. Unit should operate properly.
(b) If resistance is zero, there is a short in the wiring inside the methane
reactor. Disconnect black, white and red leads of the methane reactor at
the terminal strip. Measure resistance between red and black leads. This
should read zero, showing continuity through the temperature controller. If
resistance if infinite, replace the controller.
(c) Measure resistance between red and white leads. Resistance should be
about 50-ohms for 120V or 190-ohms for 220V operation. If resistance is
zero or infinite, replace heater. If infinite resistance, the heater is open
and will not heat nor blow the fuse. In addition, the METHANE HEAT
lamp will remain on constantly.
condition, the fuse will blow.
NOTE: AADCO Instruments, Inc. offers a rebuilt methane reactor for a
discounted cost with the trade-in of the depleted unit.
13.25 If the pyrometer indicates a temperature other than 290 C ± 10 C and the
METHANE HEAT lamp is cycling, the methane reactor is at proper operating
temperature but either the pyrometer or the thermocouple is defective.
(a) Disconnect the thermocouple electrical disconnect between the methane
reactor and the pyrometer.
thermocouple at the female disconnect leading to the methane reactor. It
should read fairly close to the 14.0-MV if the unit is at operating
temperature. If not, replace the thermocouple.
If zero resistance, indicating a short
Measure the DC voltage output of the
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