Introduction
After what I suspect was a power surge a while back, my nice $450 electrostatic air cleaner became non-functioning, I was determine to find out why. I have to give GeneralAire credit, they actually have a usable troubleshooting section of their manual to help isolate functions and problems, and a part list to identify things, unfortunately the parts that needed replacement were more than an entire new unit… so I dug in a little deeper.
Parts
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The first was to test the front panel LED indicator to rule out stupidity, but I had a good idea it went well beyond an indicator light as the filter had not been getting dirty.
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This was a simple test, touch a 9V battery in the correct polarity to the red and black wires coming off the HV board, the indicator should light up brightly, and it did.
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Making sure the yellow and blue wires from the 24VAC transformer are off the HV board, clip on a volt meter and energize the unit with the front panel switch. I should have seen voltage there for about 5 seconds as the air proving switch turned on then off, but got nothing.
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Per the manual, I moved back to the air proving switch, a small board with a PTC thermistor and a triac that energize to provide 120VAC to transformer. With output lead 4 disconnected, connect he volt meter between pin 1 and 4.
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Energize the unit once again. Still only a few 100mV. Carefully check that there is 120VAC on the incoming posts 2 & 3, yep it's there.
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At this point, I had three suspects, the transformer, the air proving switch, and after closer inspection, I saw a brown discoloration on one of the high voltage capacitors.
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I decided to start with the transformer. After removing it from the unit, I checked the secondary and measured about 7 Ohm, reasonable. The primary was open, just to make sure I slowly opened the primary coil and after getting back to the winding, didn't see anything obvious, but it was still measuring open.
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On removing the air proving switch, the thermistor checked out at about 1kOhms and responded with a squirt of canned air. All the discretes checked out except for the triac.
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At this point I needed:
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Air Proving Switch $76.38
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Transformer $54.30
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Power Control Board $310.27
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New unit: $461.99
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Looking up the individual parts:
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Triac TO220AB $1.22
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50VA transformer $22.70
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2000pF cap, 6kV $0.77 each
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Total parts plus some spares and a thermistor $38.60
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Looks like I'm fixing this thing.
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Reverse the order of testing:
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Connect the air proving switch and verify voltage at pins 1 & 4.
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Connect the transformer and verify 24VAC out when energized and the air proving switch is cold.
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With everything connected, powered up the unit and watched the indicator come on and go off. I turned on the fan to the air unit and the indicator came back on and very carefully bringing the voltage probe near the HV lines, I got some nice chirping.
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To reassemble your device, follow these instructions in reverse order.
