Power Supply Board - GE APN08 Series Technical Service Manual

Power Supply Board

The power supply board is located in the power supply housing behind the outer cover next to the
evaporator fan. The power supply housing cover is held in place by 7 Phillips-head screws.
Caution: Lock tabs on all low voltage wire connectors on the power supply board and operation/smart
board are fragile. Tab breakage can occur if excessive release pressure is applied.
Power Supply Board (PSB) Connector Locator
1 - Low water level switch (CN10) - 5 VDC should be measured across the two white wires in the white
connector when the low level switch is open.
2 - High water level switch (CN9) - 5 VDC should be measured across the two red wires in the white
connector when the high level switch is open.
Note: If CN9 and CN10 are reversed, the compressor will shut off after water trips the pump switch
(approximately 60 seconds). The condenser fan will continue to run for approximately 40 minutes.
3 - Thermistors (CN1). Pins #1 and #2 are the room ambient thermistor. Pins #3 and #4 are the
evaporator thermistor. The display will default to 75 F with an open connector. Output from the
board is 5 VDC between pin #1 and #2 and also between pin #3 and #4 with the connector
unplugged.
4 - Louver motor (CN5). Motor is approximately 200 Ω, 8 VDC should be measured between pin #1
and #5.
5 - CN19 to operation/smart board (CN15). CN19 is permanently attached to the PSB. 12 VDC should
be present between pin #1 and #5.
6 - CN14 to operation/smart board (CN20). CN14 is permanently attached to the PSB.
7 - Water pump (CN13 and CN2).
8 - Compressor capacitor (CN7).
9 - Terminal block (CN8 neutral).
10 - Transformer (CN12 primary). 120 VAC output from board to primary. Primary transformer
resistance is approximately 125 Ω.
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