v3.0 board fried? install boost control wrong

[archy355]

I am in need of some help. I was trying to get the boost control to work. I followed these instructions.

{Mount the FET on the heatsink. Place the supplied insulator under the FET else it will cause the circuit to fail.

Top Leg: Goes to ground
Middle Leg: To harness (usally through the spare IAC outputs)
Bottom Leg: To JS11 through a 100ohm resistor

Jump the top and bottom leg with the 10K resistor

Solder the banded end of your diode to S12, and run it to the middle leg of the FET.}

I soldered the diode in backwards and it seemed to burn something up. I have checked all the resistors and diodes. it appears as though the ms2 daughter card is not getting power, when I check for power like the manual says at pin 1 and so on. can someone lead me in the right direction as to what could have burned up. or inform me as to how the power would flow so I can install some jumper wires if the board burned up.

[billr]

You have already removed the backwards diode, correct?

[archy355]

yes removed the diode. it appears as that power is not getting to the ms2 card now.

[Matt Cramer]

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.

[archy355]

thank you for your help matt, here are the findings

supply volts is 9.5 from my stim.

S12 = 0
S12C = .05
Q9 = 9.5
Q12 = 9.5
nonband D3 = 0V
left leg U5 = 0
banded D9 = .09

for the spots that should have 5volts:
+5 proto = .20
nonband D9 = .20
right leg U5 = .20
banded D19 = .20
pin 1 = .20
pin 20 = .20
pin 31 = .20

[minimoose]

Don't mean to hijack your thread but I need help,

I just finished building megasquirt 2 and I tested all the pins you say and I have battery voltage on all of the spots that should have 5 volts.

Please help!

[Matt Cramer]

This may be a burned component if you're lucky, a burned trace if you're not. Check the voltage across MOV1.

[archy355]

looks like it is getting voltage across it.

[archy355]

sorry i rechecked the mov1. it has .20 volts going accross it. i found the schematic in the manual for the v3 board. ive traced out the circuit and it looks like it has continuity throughtout the board but for some reason the system is only receiving .20 volts. so my guess is a component must be burned up somewhere, but i havent been able to find it. even at the voltage regular u5 it only has .20 volts going into it.

[DaveEFI]

You should get a reading of 12v across MOV1 I'd first check the tantalum cap C16 for a short circuit. But it could really be anywhere on the 12v rail. If you remove one leg of D10, that will sort of split the rail into two. Any component across the 12v rail could fail short circuit.

It's a bit difficult to teach fault finding - it's something which comes with experience.

[Matt Cramer]

Also have a look at the trace underneath board on the DB37, starting at pin 28. Check to see if it's burned.