Black & Decker Clothes Iron (IR0175W)

The main job of an iron is to make a flat piece of metal hot so we can use it to flatten wrinkles in our clothes. This particular iron was retired when it could no longer reliably do that one job. When plugged in, it would get hot as expected. Once it reached a certain temperature, it would slowly cool down, which is also expected. But it failed to turn the heat back on quickly. This iron would cool to almost room temperature before it would heat itself back up. I tried to find other use for it, but I’ve decided to take it apart. If I can fix it great, if not I will dispose of the remains.

No manufacturing date was visible on the product label. We see the old Black & Decker logo and searching for this model number IR0175W returned no results. Judging by appearance I would guess it is roughly twenty years old, because Apple made this “Bondi Blue” color cool in 1998 with the original iMac. Within a few years, everything made of plastic was available in this shade of translucent blue alongside white plastic.

The only externally visible fastener was a Torx 10 screw just below the power wire. It’s even a “security” Torx with a little post in the middle. It was quickly dispatched so this back plate can be removed revealing ordinary Philips head fasteners for the remainder of this teardown. “This would be easy!” I thought.

I was sadly mistaken. I couldn’t figure out how to remove the top plate elegantly and resorted to brute force. After it was torn off, I saw it was secured by a Philips fastener that was hidden under the steam pump button. (See green rectangles in above picture.) This button had plastic clips so that, once installed, it could not be removed. I see no way to open this without damage. This external enclosure is ruined, I’m not going to be able to fix it and put it back together.

The circuit board in the handle is interesting. It had 120AC line (red, labeled L AC2) and neutral (blue, labeled N AC1) coming in, and an output line (yellow, labeled OUT). The yellow and blue wires connect to the body of the iron, so this blue rectangular relay is definitely capable of switching the heat on or off. However, it is not in charge of temperature control, because there is no way for it to sense the current temperature or read the user adjustable temperature setting dial. This circuit board does have a mechanical sensor of some sort in the black rounded enclosure visible just to the right of the blue relay. It makes sounds when I shake it that is consistent with a little metal ball inside. I hypothesize this circuit implements the safety timer. If no motion is sensed over a time period, turn off the heat.

Removing the top deck and temperature dial revealed the Bondi Blue water reservoir. We can see the top end of the temperature regulation mechanism where it connected to the temperature dial.

Not much new is revealed once the water reservoir was removed. I was amused to notice that the reservoir was installed incorrectly at the factory. We can see the orange water gasket leading to the hot bits was crushed out of place for roughly one quarter of its perimeter. Thankfully I never noticed a leak from this error, though I didn’t use the steam function very much anyway.

The bottom-most layer in this stack: Heating elements permanently enclosed and bonded to the metal ironing surface. The temperature regulation system is fastened to the top of this layer.

Temperature regulation is a mechanical system centered around a bimetallic strip. Simple in theory: the circuit is closed to heat things until the strip changes its shape and opens the circuit. The system closely cools until the strip changes its shape again to close the circuit and repeat the process. Turning the heating level knob (top layer) I see it is a threaded contraption that ends in a white insulator point pushing on the second layer. Turning the dial subtly changes the bimetallic strip assembly geometry so it changes shape at different temperatures.

I turned the dial back and forth through its range of motion (~270 degrees) and I could see and hear the bimetallic strip pop back and forth. I did this a few times before I realized… wait, that’s not supposed to happen! This thing is at room temperature. A clothes iron shouldn’t be turning its heating element off at room temperature. This behavior is consistent with the observation this iron cools off too much before heating back up. I assert this bimetallic strip should remain at the closed position through the entire range of this dial at room temperature. But the only candidate for adjustment is a tiny flat head brass screw at the top of the dial, securely fastened by a blob of adhesive. I managed to damage the brass before I made any progress breaking that adhesive blob, ruining my chances of fixing it. This teardown was instructive but ultimately a failed repair. I disposed of the remains and moved on to the next teardown.

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