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Old 05-07-16, 07:22 PM   #8
jeff5may
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Join Date: Jan 2010
Location: elizabethtown, ky, USA
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OK, so I rigged my countermeasure in today. I found a few relays, but they were all the wrong size to fit in the board. I robbed an NPN transistor out of one of the donor boards ( a PN2222a, Fairchild equivalent of 2N2222) and rigged it between the micro and the relay driver IC. I desoldered the input pin from the board and filled the gap with super glue. I found a good ground on the board (hole for a capacitor not stuffed) and stuck the emitter of the NPN in it. I tacked a 10K resistor between the micro output pin for the RV and the base of the NPN. I twisted the end of a leg of a 1K resistor around the driver IC pin previously desoldered and removed it. I melted a teeny blob of solder into the eye and tacked it onto the end of the pin. I twisted and tacked the leg around the NPN collector, then ran the other leg of the resistor to a regulated 5 Volt hole in the board (other leg of the capacitor not stuffed: C5 next to U3). See pics in previous post for reference.

Long story short, the transistor did its job. The thing cools in cooling mode and heats in heating mode. Got everything stuffed back inside the unit, secured parts with screws, and set it to cool the outdoors while I washed my car. I took some pics, but they all ended up smeared or out of focus enough not to be proud of. The awesome thing today was finding out the control panel in the kit is nearly exactly the width of the bezel for the twisty knob plate. Plus I found some batteries for the remote control and played with the unit that way.
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