GE DPGT750EC/GC Technical Service Manual

GE DPGT750EC/GC Technical Service Manual Manual pdf 34 page image

– 34 –Note: Proper leveling of the dryer is vital foraccurate sensor drying. Excessive rearwardadjustment will cause clothes to tumble towardthe rear of the drum, preventing contact with thesenor rods, thus producing a false drynessreading.Testing the Moisture Sensor Circuit1. Place the dryer in Factory Test Mode:a. Press HOME, then HELP.b. Press and hold the HELP and START/STOP pads simultaneously for 3 seconds.A dry sensor rod circuit should display a voltage of4.75 VAC or higher under MOISTURE(S) test.2. Wet a cloth and place it across the sensorrods. The display voltage should drop to1.0 VAC or less if the circuit is workingcorrectly.Moisture SensorThe moisture-sensing circuit consists of twosensor rods mounted in the drum front beneaththe lint filter opening.• The sensor rods are connected to the maincontrol board. The rods are spaced about½ in. apart, which creates an open circuit tothe control.• The control board utilizes a low-voltagecapacitor that charges to approximately 5VDC when the circuit is open and dischargesto less than 1 VDC when the circuit is shorted.• When wet clothes tumble across the tworods, the clothes create a very low resistancebetween the rods, which discharges thecapacitor.• As the clothes become dry, their resistancevalue increases and the charge across thecapacitor builds to approximately 5 VDC.Sensor RodsIgnitor and Flame Detector• When the electronic control calls for heat,120 VAC is supplied to the ignitor.• The flame detector, which is in series with theignitor, is closed.• When the ignitor reaches a high enoughtemperature, the flame detector opens.• The electronic control senses the opening ofthe detector and energizes the gas valves.Testing the Ignitor and Flame Detector Circuit1. Place the dryer in Factory Test Mode:a. Press HOME, then HELP.b. Press and hold the HELP and START/STOP pads simultaneously for 3 seconds.2. Press START/STOP to begin the test.• The FLAME SENSOR test will displaywhether the detector is open or closed.• In the OFF position, the flame detector isclosed (room temperature/low heat). In theON position, the flame detector is open(hot).