I have recently finished rebuilding after welding and respraying my Mazda mx5 and want to fit a 1.8vvt engine to the car so bought the Speeduino 0.43 kit. I am quite handy and have a fair knowledge of electronics and DIY.
Preparing to test the board using ardustim and I put my power supply onto the 12v inputs on the board and without realising it put 24v DC into it instead of 12v. The varister U2 gave off some magic smoke and is now showing open circuit.
Whilst testing the circuit for other issues after removing the varistor I have noticed that my multimeter shows 44 ohms between the positive and negative pins on the screw terminal.
Could you please let me know if this is normal? Should I just order and refit a new varistor and put a good known 12v supply onto the board to continue testing or do I still have an issue?
I have checked the solder points throughout for any shorts and they are clear. The Diodes are all correctly installed as well as the 2 polarity sensitive capacitors.
I have attached 2 photos after removing the varistor if you could have a look to spot anything obvious I am overlooking.