98cobra+75280z Posted May 15, 2011 Share Posted May 15, 2011 I have a MS1 v2.2 and i keep burning out my Q5 transistor. What could cause this?? I can't seem to get my car to fire over and idle, I am also trying to get my timing set but i can't get the middle led on the megasquirt to light up when i set the timing to 60 deg BTDC. What is the trick to this? The wiring is correct and i have gotten the led to light up before the Q5 burnt out but now it won't light up anymore. any help is greatly appreciated. thanks guys Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted May 16, 2011 Share Posted May 16, 2011 What is the resistance of your injectors? Are you running injector resistors or a flyback board? Quote Link to comment Share on other sites More sharing options...
98cobra+75280z Posted May 16, 2011 Author Share Posted May 16, 2011 What is the resistance of your injectors? Are you running injector resistors or a flyback board? I have stock 280zxt injectors and im running a stock '75 injector resistor pack. I took the resistor pack apart and ran one resistor on each injector and the resistors measured out around 6 ohms each. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted May 17, 2011 Share Posted May 17, 2011 You must have a short somewhere. Did you build the box? How are your injectors wired up? Quote Link to comment Share on other sites More sharing options...
98cobra+75280z Posted May 17, 2011 Author Share Posted May 17, 2011 You must have a short somewhere. Did you build the box? How are your injectors wired up? I wired the injectors from Mobys writeup with one 6 ohm resistor on the +12v lead to each injector and then the grounded sides of the first three injectors are grounded to bank 1 and the second three to bank 2. Yes i build the box and its very possible that i made a mistake somewhere, is there a good way to check for a short?? I took the box out of the car and noticed that the cpu chip wasn't contacting very well, so i pushed it down and the tach on megatune began to work again. However i then accidentally flipped the rpm potentiometer from PNP to NPN and the tach stopped working again. I couldn't get it to work anymore so i desoldered the Q5 and put another transistor in and still i can't get the tach to work. I can't figure out what is wrong with my MS, sorry for all the questions and problems. Thanks for your guys advice. Quote Link to comment Share on other sites More sharing options...
mobythevan Posted May 17, 2011 Share Posted May 17, 2011 Your resistor wiring sounds correct. I'm not following this line: However i then accidentally flipped the rpm potentiometer from PNP to NPN and the tach stopped working again. Can you elaborate on what got flipped? Quote Link to comment Share on other sites More sharing options...
98cobra+75280z Posted May 22, 2011 Author Share Posted May 22, 2011 Your resistor wiring sounds correct. I'm not following this line: However i then accidentally flipped the rpm potentiometer from PNP to NPN and the tach stopped working again. Can you elaborate on what got flipped? Sorry about how vague that was. If you look at the MegaStim, version 2.21, below the RPM pot there is a box that is a switch. The label for the switch flips from PNP to NPN. I have no clue what these labels mean or even what the switch is for but when i switched it the tach stopped working in Megatune and i can't seem to get my tach to work again. Quote Link to comment Share on other sites More sharing options...
Matt Cramer Posted May 26, 2011 Share Posted May 26, 2011 Just realized I was thinking of the wrong board - on V3.0s, Q5 is an injector driver, on V2.2s, it's the FIDLE output. What exactly is wired to pin 30? Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 26, 2011 Share Posted May 26, 2011 This probably won't help with your overall problem, but NPN and PNP are types of transistors. The switch would have something to do with the expected input and output on that circuit. Transistors are used to fire your injectors and ignition coil by controlling current flow, so the switch setting would be important. Here's a Wikipedia link - http://en.wikipedia.org/wiki/Bipolar_junction_transistor Search NPN, PNP and transistor on Google if you want to dig in to it further. Good luck, the details are over my head... Quote Link to comment Share on other sites More sharing options...
98cobra+75280z Posted May 27, 2011 Author Share Posted May 27, 2011 Just realized I was thinking of the wrong board - on V3.0s, Q5 is an injector driver, on V2.2s, it's the FIDLE output. What exactly is wired to pin 30? I have the MS wired to the relay board so Im pretty sure thats all wired right. Quote Link to comment Share on other sites More sharing options...
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