I noticed that one of the bits had some scotch tape on it and looking closer at it I saw one of the SMDs had fallen off and I had taped it to the bit so I didn't lose it. Rather than crudely soldering it back on I thought it was the perfect opportunity to try hot air soldering using a hot air rework station. The pads looked okay and there was actually enough room to solder it but here was an opportunity to try something new!
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| The "before" pic with lonely capacitor fallen off. |
I had actually done some research on hot air stations a while back and have the Hakko FR-810B wishlisted but it's a tad pricey (well over $1000 CAD!). Cheaper options exist, such as this Toolour version that was recommended to me. Once I started looking into it a bit more I saw a basic version that seemed to be clones of a model labelled 858D. I don't know if it started out as a commercial product or just a generic clone, but it's a pretty simple device. It has a ceramic heating element in a handheld wand, with fan control and an adjustable digital readout of temperature.
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| Note the temperature reading with the wand in holder. Does this mean there's no standby mode and is continuously heating? |
These type of heating stations can handle 400-1000 watts so it made sense to open it up before plugging it in to check some basic safety features. The 858D clones have a history of mismatched PCB designs, mis-coloured wires and questionable grounding. There were four areas to review:
#1: Check continuity of power plug
Put your multimeter in continuity mode and do a check of the power cord. This is a component that is mass-produced and used in many different electronics so it's probably not specifically made for the high loads of hot air. Check that the hot, neutral and ground wires are properly labelled (if applicable) on the plug and are not shorted against each other. Do the same for the power input plug.
#2: Check hot/neutral wires
Wire colours are important to regulate since they carry live electricity and workers may get sloppy if they do not have a load checker on hand. This doesn't mean it's a foolproof system, you should always double-check but it's a good start along with rules of thumb like "one hand in the pocket" rule that says to work one-handed so any potential shock does not across your body. In North America hot wires are black, sometimes red, blue or brown, neutral is white, sometimes grey, and ground wires green. Luckily my 858D had correct colours which I double-checked led to the correct inputs and outputs. Also check that the hot wire is leading to the switch and not the neutral; if it leads directly to the board it can still charge it even if it's switched off.
#3: Check fuses
Fuses are hit and miss since they're being shipped in a variety of conditions. I've received broken fuses, missing fuses, and mismatched fuses. My 858D had the fuse located in the power input plug, and it was correctly laid across the hot wire. Other 858Ds have a separate physical fuse so make sure it's wired correctly.
#4: Check grounding
Grounding adds a layer of safety by providing an alternate method of discharge to the ground instead of through you. Check the path of ground using continuity from each grounding point on the PCB, transformer, and case through the power plug. My 858D case was powder-coated so I had doubts about the continuity through the screws. I filed through the paint on numerous screw points and the mounting screw of the ground wire since it was attached to a standoff from the case. I also checked that the transformer legs were making good contact with the case in case there was a short. All-in-all it was a reasonably well-built device and there wasn't too much work I needed to do, just a lot of double-checking.
Wire colours are important to regulate since they carry live electricity and workers may get sloppy if they do not have a load checker on hand. This doesn't mean it's a foolproof system, you should always double-check but it's a good start along with rules of thumb like "one hand in the pocket" rule that says to work one-handed so any potential shock does not across your body. In North America hot wires are black, sometimes red, blue or brown, neutral is white, sometimes grey, and ground wires green. Luckily my 858D had correct colours which I double-checked led to the correct inputs and outputs. Also check that the hot wire is leading to the switch and not the neutral; if it leads directly to the board it can still charge it even if it's switched off.
Fuses are hit and miss since they're being shipped in a variety of conditions. I've received broken fuses, missing fuses, and mismatched fuses. My 858D had the fuse located in the power input plug, and it was correctly laid across the hot wire. Other 858Ds have a separate physical fuse so make sure it's wired correctly.
Grounding adds a layer of safety by providing an alternate method of discharge to the ground instead of through you. Check the path of ground using continuity from each grounding point on the PCB, transformer, and case through the power plug. My 858D case was powder-coated so I had doubts about the continuity through the screws. I filed through the paint on numerous screw points and the mounting screw of the ground wire since it was attached to a standoff from the case. I also checked that the transformer legs were making good contact with the case in case there was a short. All-in-all it was a reasonably well-built device and there wasn't too much work I needed to do, just a lot of double-checking.
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| Pulsing like a heartbeat |
After that it was pretty uneventful...until I discovered what makes littleBits so awesome. The magnets! A wrong nudge one way or the fan blowing a certain angle and the capacitor flew off sticking to the magnetic side. I had to hold it down with tweezers until the surface tension of the molten solder affixed the capacitor enough to the surface. Once done I noticed I had melted the plastic housing a bit but thankfully the mount and the magnets still work.
