
Not looked too closely at those soldered joints hm.... some heat shrink (best option) or other insulation (perhaps using something from stripped wire) would have helped. I have recently found at Lidl Parkside plastic boxes containing varying sizes and colours of Heat shrink for I think around £3. Well worth having a box in stock, I have 2 as I forgot that I already had one when they were in again!Not being an electronic expert in anyway whatsoever, not putting a fuse in the system seems a bit rash. The other thing, it may be just the camera angle, but from what I can see, the soldered joints of the black and white wires on the front of theboard appear to be a bit poor, the black one looks close to touching the heat sink, wold that be some of the cause of your problems?
A little soldering tip for Mr Cook, strip a short section of the wire and pre tin the wire before connecting. Use some flux for that final joint you will get better connections to boards that way. Oh and a gentle clean off of any flux residue. If you do in future use any heat shrink make sure it is a couple of inches away from the joint when you solder it, allow to cool then move the shrink and shrink the shrink in place by holding the side of the iron close - not the tip you do not wish to unmelt that joint.