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https://cajinnovations.com/yabb0/YaBB.pl MyECU >> MyECU Advanced usage >> Q6 busted https://cajinnovations.com/yabb0/YaBB.pl?num=1375379670 Message started by raz on 08/02/13 at 03:54:30

Title: Q6 busted
Post by raz on 08/02/13 at 03:54:30

Hi

I just repaired a dead My16M, Mk IV or so, and it quickly turned out Q6 was busted. I replaced it and all is fine. What could have caused this (provided it wasn't just a bad component in the first place - it had thousands of kilometers on it though)? What does Q6 do? Is this the one that latches the relay?

raz

Title: Re: Q6 busted
Post by YaBB Administrator on 08/02/13 at 10:28:47

I've seen a few of those failures. It failed with the ECU constantly powered right?

Q6 is the FET that pulls the ECU power relay. Its gate is fed via a voltage divider but I think there is some inductance there that is causing a spike to take out the FET.
On later versions I have added a cap in parallel with the resistor to ground as you can see here.
http://www.cajinnovations.com/MyECU/My16MMkVII/pics/My16M_PCB.png

You should add the cap, 0.1uF, to yours.

Title: Re: Q6 busted
Post by raz on 08/02/13 at 20:14:47

If you mean powered regardless of ignition switch, I'm not sure. Running off 9V the boost voltage and 5V were alright but fuel pump did not prime - a little unintuitive to me but I started with checking the FETs so I found it immediately. I'll consider adding the cap. Maybe certain relays are worse, I think mine has internal caps or resistors and that could mitigate the problem too, right? This one failed on a friends bike.

Title: Re: Q6 busted
Post by YaBB Administrator on 08/03/13 at 08:57:00

That sounds like the same failure. It doesn't prime because it does not turn on with the key. Its already on.