Very frustrated, any help welcome

[nuk1ear]

Ok well, all 4 TIP122 modules are insulated fine, infinite resistance on all. But at the output of INJ 1 to the 12v+ supply im testing with, i get a 12V reading. All others are 0v. Something is wrong in the driver, i just need to find it.

What other screwups on the board would cause this? How can i test each TIP122 and make sure theyre ok?

[racingmini_mtl]

Check the voltage on pin 1 of the TIP122. It should be close to 0. If it is and the output is on then the TIP122 has failed and needs replacing. If the voltage is above 1V then the TIP122 is likely fine but something else is wrong. Check voltage on pin 1 of the LM1949 (U1-4): it should be 0. If it is higher than 2V then there is a problem on your MS or your wiring to the p&h board. If the voltage is 0 and you have a voltage at the TIP122 then the LM1949 has failed and needs replacing.

Jean

[nuk1ear]

im 100% sure its a problem in the injector driver. I checked all outputs and only injector 1 has 12v across the output and power source (when powering it with a 12v supply). All other outputs are not pulling ground, only injector 1 which is constantly pulling ground when powered and no input triggers are being supplied. This is when just bench testing (applying 12v and ground to power the unit, then measuring injector ouputs to power supply).

Ill check those TIP122s as you describe tonight!

[billr]

And the voltage from ground to the base of that TIP122 is essentially zero? If so, remove the TIP122 and make sure the voltage from ground to the injector lead (with injector connected) is now 12V; that will ensure the problem was the TIP122 and not some other short-circuit in the board or wiring. And you will be all ready to put in a new TIP122. I'm pretty sure they are quite inexpensive, things could have been a lot worse!

[nuk1ear]

And the voltage from ground to the base of that TIP122 is essentially zero? If so, remove the TIP122 and make sure the voltage from ground to the injector lead (with injector connected) is now 12V; that will ensure the problem was the TIP122 and not some other short-circuit in the board or wiring. And you will be all ready to put in a new TIP122. I'm pretty sure they are quite inexpensive, things could have been a lot worse!

yeh could have been much worse! Cracked block/bent rod/valve etc. Anyways, i measured output from the injector 1 output to power supply. I havent tested the TIP122 yet, ill do that tonight (sorry im in AUS, big time difference, im at work atm). I checked the resistance from TIP122 base to ground and it has infinite resistance, so insulation was fine, this was the same on all of the TIP122 parts.

[nuk1ear]

god damnit, both the TIP122 and LM1949 are ok, i checked the input trigger voltage at input trigger 1 and its reading 5v. Where the hell is it getting 5v from? I have nothing wired in except the power supply, this is not on the car, so its definitely a problem in the driver somewhere. But where? Checked Q6 and theres 5V there, but Q7 is fine. So its upstream of Q6 somewhere right? 5V at pin 1 on U1. So i have no idea what is wrong? what can i test next? i searched all over the board for bridged or any components installed wrong/diodes etc. It all appears fine

[racingmini_mtl]

Which p&h board do you have? Is it a V1.1 or a V2.0? From what you say you seem to have a V2.0. If that's the case then the fact you see 5V at the LM1949 means that either Q6 has failed or there is a solder bridge on Q6 or there is something wrong with R14.

Jean

[nuk1ear]

I have the 2.0 I can test the resistance of R14 obviously. How can i test Q6? why would it be getting 5v?

[racingmini_mtl]

There is a pull up to 5V (R10) between Q6 and U1. This is needed to get a signal at pin 1 but it should be grounded by Q6 if it works normally. Check the voltage on R14 on the side closest to Q6.

Jean

[nuk1ear]

Ok well i get 5v at the R14 side of the transistor. So the transistor isnt pulling ground as it should right? so its stuffed? Ill try swapping one of the other transistors there and see if it works then, then ill get a new one if its dead

[nuk1ear]

OK,
replaced the transistor and it works again wooooo!

[racingmini_mtl]

Good to see you solved it.

Jean

[nuk1ear]

is there any way i can test each output and make sure that the box is working as intended???

[racingmini_mtl]

You can test the output by grounding the input and seeing if that activates (grounds) the output. However, to see if you get the intended peak and hold phases, you need an oscilloscope. For the simple test, you can use a LED or light bulb.

Jean

[nuk1ear]

I will test it as you described, just to make sure its at least activating correctly. I believe that my other problems (hard starting, chopping running, these things happen randomly) are related to bad cam singals.