Power Issues MS1 v2.2

Ask questions about DIY board assembly issues, fault finding and testing. (Covers all Megasquirt versions and board.)

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Brickerz
MS/Extra Newbie
Posts: 8
Joined: Sun May 11, 2014 5:23 pm

Power Issues MS1 v2.2

Post by Brickerz »

Hey guys,

I got my engine/trans back in the car and went to fire it up, this weekend (The car was running with this ECU before breaking a couple pistons). Ended up with smoke coming from the MS box and pulled it out to do some testing. I did find that my wire to my alternator had broken that had the in-line resistor in it, I'm assuming causing a voltage spike to the box. I also saw that I had a 10A fuse in the ECU slot, instead of a 2-3A fuse... After pulling out the box, I opened to find that C15 had gone up in flames. I ordered the replacement C15 22uf tantalum 399-1420-ND and soldered it in. However, I'm still not getting 5v where I need it on the board and I have no connectivity to TunerStudio or injectors firing... I also have some 5v regulators on hand if I need to replace it.

I followed these steps found in other posts for power. I'm using a stimulator with a 12V 1A power supply.
To check for a short in the Megasquirt PCB, power up the Megasquirt on a Stimulator or on the car and check the following points for voltage with a multimeter.

You should find the same voltage as the battery voltage on the following points: the small hole to the right of the larger three holes marked X11, X12, and X13, the top (non-banded) end of D20, the left leg of U5, and the left (banded) end of D12.

You should have 5 volts at the following points: the right (non-banded) end of D12, the right leg of U5, and pins 1, 20, and 31 of the CPU.

Let me know where you find the correct voltages, and where you find the wrong ones.
The only place I can see 12v is at the little hole to the right of X11, X12 and X13. I have no voltage anywhere else. All checked against Pin 19 on ECU, which has continuity with the ground side of the power supply on the stim.

X11, X12, X13 - 12V
The top (non-banded) end of D20 - 0V
Left leg of U5 - 0V
Left (banded) end of D12 - 0V

The right (non-banded) end of D12 - 0V
Right leg of U5 - 0V
Pins 1, 20, and 31 of the CPU - 0V

****EDIT****
Just found a burnt trace between the banded side of D7 which leads to an open hole that tracks back to the top non-banded side of D20. Will fix and re-check voltage.

****EDIT 2****
Ok, disregard, haha. That was the problem. It's now up and running!
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