American Dryer Corp ML-55II Procedure for Functional Check of Replacement, Theory of Operation

PROCEDURE FOR FUNCTIONAL CHECK OF REPLACEMENT

COMPONENTS _________________

Microprocessor Controller (Computer) Board _________________________________

Upon completing installation of the replacement microprocessor controller (computer) board, reestablish power to the dryer.

Start the drying cycle by pressing any of the preset cycles in letters A-F.

Verify that the applicable indicator lights on the microprocessor controller (computer) board are lit. (Refer to the illustration below.)

For Models with Johnson Direct Spark Ignition (DSI) Controller (G760) ________

Theory of Operation:

Start the drying cycle. When the gas burner ignites within the chosen trial for ignition time (6-seconds), the flame sensor detects gas burner flame and signals the DSI module to keep the gas valve open as long as there is a call for heat. The DSI module will “Lock Out” if the gas burner flame is not sensed at the end of the trial for ignition period. The trial for ignition period will be repeated for a total of three (3) retries/ trials (the initial try and two [2] more retries/trials). If the flame is not sensed at the end

of the third retry/trial (inter-purge period of 30-seconds) the

DSI module will “Lock Out” (light emitting diode [L.E.D.] diagnostic indicator flashes).

A steady L.E.D. indicator indicates normal operation.

No L.E.D. indicator indicates a power or an internal

failure has occurred.

For Models with Fenwal Controls DSI Module (128937) _______________________

Theory of Operation:

Start the drying cycle. When the gas burner ignites within the chosen trial for ignition time (8-seconds), the flame sensor detects gas burner flame and signals the DSI module to keep the gas valve open as long as there is a call for heat. The DSI module will “Lock Out” if the gas burner flame is not sensed at the end of the trial for ignition period. The trial for ignition period will be repeated for a total of three (3) retries/ trials (the initial try and two [2] more retries/trials). If the flame is not sensed at the end of the third retry/trial (inter-purge period of 30-seconds), the DSI module will “Lock Out” (a red L.E.D. diagnostic indicator will flash).

An unlit red L.E.D. diagnostic indicator indicates normal operation.

A lit green L.E.D. diagnostic indicator indicates dryer controller is calling for heat and that all interlocks have been satisfied.

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