MSefi.com read only forum (Jan.15,2018)

not sure what all info is needed so here we go,...Jumpered, (xg2-xg1) (tsel-optoout) (top of r26-330ohm resister-igbtin) (igbtout-pin36) (tachselect-optoin)
Everything was assembled, connected to the stim everything but tps and rpm were working, rpm because of backward diode(i believe) connected to the car, KOEO, blew the 12v 2amp fuse, and the jumper between igbtout and the hole for pin 36 trace. looked the board over, forgot the mica insert on the back of q16 i believe its the bip 373, placed mica insert, plugged in stim board,. no led's, and 9v battery gets hot. with the stim unplugged, no leds, battery doesn't get hot. so i am thinking i have a short in my main board i just cant find it now. Any insight, or assistance is greatly appreciated.

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: S12, S12C, the center legs of Q9 and Q12, the left (non-banded) end of D3, the left leg of U5, and the left (banded) end of D9.

You should have 5 volts at the following points: S5, the two +5V holes in the proto area, the right (non-banded) end of D9, the right leg of U5, the left (banded) end of D19, 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.

so i should attempt to check for the voltages, even if it heats the 9v battery almost instantly? just for clarification.

Since you've had a couple of build errors, check everything which is polarity sensitive is the correct way round. Including the tantalum caps.
I'd also remove the processor chip until the voltages given about check out ok, and it doesn't heat up the PP3.
Other classic place to have shorts is at any of the small transistors.

Did you you the stage by stage testing as you built it - as given in the MegaManual build instructions?

my apologies what is the pp3?, and i did the step by step checks, everything worked like it should, i bridge the backward diode and i would get rpm signal, installed the heatsink, put it in the car and -pop- the 12v fuse went, thats when i found i had the bip373 and needed the mica insert, i installed the mica insert, checked over everything else, and -pop- it blew the trace (for pin36-the hole that jumps to igbtnout) out of the board and the 12v fuse,

PP3 is the 9v battery which the Stim battery connector fits. Or may be called an MN 1604. It can't deliver enough current to burn out a PCB track. Which is why I asked about the testing before fitting to the car.

The battery getting hot likely means there is a short somewhere.

it looks like my stim board is fried, im going to have to order another one, i replaced what i hought was bad, and its still not working..

Refer to the external wiring diagram, and power up the MS with a 9 volt battery direct, ie no Stim. Does the battery still get hot?