Tuesday, 23 March 2010


Well after finishing my Exam and having a little more time on my hands I managed to do a little on the Megasquirt assembly. Well to say a little would be an understatement.

I finished the board a couple of days after my exam which was on the 9th March, and after plugging it into the stimulator, I heard a little click and the computer refused to communicate with the Daughter-board (main chip). After removing the Daughter-board I checked the voltages on the mount finding 2.5volts where 5volts should have been!

Well after panicking and fearing I had burnt the whole lot out, I followed the trouble shooting instructions on the Megasquirt main site, I checked all the build steps one by one and found nothing. So I went onto the Megasquirt Forum, where it is clear I am a novice at this, The fella I bought the kit from asked if Diode D19 (Capacitor 0.1µF 50V 10% CER RADIAL - X7R) was getting hot! Sure enough it was.

His suggestion was check all the board for bridged solder joints and replace Diode D19.

On checking the board out with a magnifying glass I found I had bridged the 12volt and the 5volt lines on Q1 which a (field effect transistors, used to drive the injectors) It was only a very very small bridge but this had burnt out D19 which regulates and protects the 5v circuit.

Now the tricky bit, get hold of a (Capacitor 0.1µF 50V 10% CER RADIAL - X7R) Maplins did not stock this item; other sites sold them but only in the 1000's. But as always I turned to EBay and found them in a shop in Japan. £2.99 for 50. They were only available in 50's so at three quid I placed the order.

Well I am pleased to say the Capacitors arrived today and I fitted the 1 needed and hey presto a fully working Megasquirt.

I have tested it on the Laptop with the Stimulator and all seems fine, I have loaded a basic Map and injection table to test the board and all seems superb.

What a relief!


1 comment:

  1. And you only need to find another 49 people who've made the same mistake and that pack of 50 capacitors will be justified ;-)