TIP 120 alternative connection points ?
 

Hi Guys,

Looking for a bit of help here….

I am looking for alternative connection points for the installation of the TIP 120, which is currently attached to the Q4 location on the MS 2 board.

I have soldered this connection twice now and really do not want to solder it again.

I see that the Emitter leg (E) of the TIP 120 can be attached to the jumper (R 39) but it is hard to see where the other two can be connected.
Any ideas ?

Also, can the Diode for the fly back circuit be installed in the Mega squirt; or does it have to be at the PWM Valve?

Thanks guys!

I assume you're referring to the idle circuit.

The collector leg can be connected to the cathode (striped) side of D8, or directly to the IDL pin of the DB37 (pin 30).

The base leg can be connected to the side of R19 which has 0 ohms continuity to the collector (pin 3) of Q20.

The emitter leg can, as you have observed, be connected to the side of R39 which is connected to the base (pin 2) of Q20. This is tricky to judge with an ohmmeter, since R39 is only 1 ohm, so observe the traces visually.




You can install it inside the ECU if you wish. This is where the flyback circuits for the injector drivers are located, and they generate a much stronger back-EMF potential.

The advice to install it at the valve is mostly academic. In theory, this will decrease radiated noise slightly, but it's a fairly trivial concern in the overall scheme.

Thanks Joe !
I will check that out tonight

yuk. sounds like you're building a MS1.


yuk yuk yuk.


why?

He said in the first post he was building an MS2, and I assume he's using a 3.0 PCB.

Nothing wrong with that. For an NA, there's not much advantage to the MS3.

there's a lot wrong with it.

like modifying the board to install a TIP120.