no communication using USB cable

[racingmini_mtl]

I had contacted Bruce when I became aware of this issue (before this was mentioned on the forum). And he indeed confirmed that they were buying the chips directly from one major distributor.

But there is always a possibility that something happened at the distributor or at the assembly place and that one or more chips from a different source get used. There's also the wording on the FTDI EULA that can lead one to believe that the new driver could brick one of their own genuine chip.

Jean

[arnold1]

Sorry for the delay of my response but I was out of town.
Glad to say it wasn't the chip!!!! It was a defect USB socket. So everything is good now and is working properly.
Thanks to you fellows I learned a few things about FTDI chips and what could happen if for some reason one has a fake chip on a board.

Thanks for all the help
Arnold

[JAM]

Sorry for the delay of my response but I was out of town.
Glad to say it wasn't the chip!!!! It was a defect USB socket. So everything is good now and is working properly.
Thanks to you fellows I learned a few things about FTDI chips and what could happen if for some reason one has a fake chip on a board.

Thanks for all the help
Arnold

So i assume you just replaced the usb socket? if so, was it difficult and a where did you get the replacement part?
Thanks

[arnold1]

I personally didn't do anything except send the MS3 to someone for repair.
As far as I know the USB socket wasn't replaced, the pins and the complete rear of the socket were stiffened up with a Pertinax plate and epoxy. Don't have any pictures, all I know is that everything works fine now....

[jleilich]

Good information. I'm having the same issues with my new build. My MS3 is not communicating with the computer and I cannot load firmware.

[Matt Cramer]

Good information. I'm having the same issues with my new build. My MS3 is not communicating with the computer and I cannot load firmware.

Does your MS3 have 5 volts on VREF when it's powered up?

[jleilich]

Good information. I'm having the same issues with my new build. My MS3 is not communicating with the computer and I cannot load firmware.

Does your MS3 have 5 volts on VREF when it's powered up?

I have no clue. Ill need to figure out how to check. I assume i'm going to get out the multimeter for this?

[Matt Cramer]

Yes. 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.

[jleilich]

Awesome! Great information Thank you. This will give me something to do when I get home tonight.

thanks again

[jleilich]

well i need to fix a burned R15 before I can move to that. It was burned before and I guess I didnt realize it. I saw something smoke but just figured out what it was. Could this cause my comm issues?

I replaced R15 but it still gets hot so I need to chase a gremlin

[jleilich]

Can someone explain this to me like I'm 3? Either my board is jacked, my multimeter is jacked, or i'm just not doing this right. Working with a Klein MM1000

First, check pins 2 and 4 on U4. If they're not getting 5 volts in the off state, turn the power off and ohm out R14 and R17, and make sure you have continuity to the CPU


Please

thank you

[slow_hemi6]

U4 is an inverting driver. So when 5v is on 2 or 4 then 7 or 5 respectively will not be outputing the 12V from pin 6. This is how you want it to be when the power is on but MS is not sending a signal to fire the injectors. To achieve this the 2 and 4 pins both have pull up resistors R14 and R17 to keep the pins high (vcc 5v present). So even with no cpu, when ms is powered you expect to see 5v at pins 2 or 4 when measured to ground. No 5v there means either the resistors have gone open or there is no 5v vcc. You should have the 5v present on either side of the R14/ R17 resistors.
Just thought I would also ask if you have checked that the IC U4 is not installed upside down? That would be bad and it's not that hard for a beginner to do.
numbering is like this. Take note of the scallop and or dot that indicates the top.

[jleilich]

Ill double check but i'm pretty sure I noticed the orientation notch when i assembled the board.

[jleilich]

Ok I'm getting no reading from my resistors. It is possible however that I am not using my multimeter correctly. Should I be putting leads on either side of the resistor? should I put the black to ground?

also how do I do this?
ohm out R14 and R17, and make sure you have continuity to the CPU.

[DaveEFI]

Ok I'm getting no reading from my resistors. It is possible however that I am not using my multimeter correctly. Should I be putting leads on either side of the resistor? should I put the black to ground?

also how do I do this?
ohm out R14 and R17, and make sure you have continuity to the CPU.

You may - or may not - get an accurate reading measuring any component in circuit. Depends on the circuit it is part of. The only sure way to measure it accurately is to disconnect it. With a resistor, a good one will never read higher than its value due to other components in circuit, but may well read lower.

[jleilich]

I also just realized I never did the testing steps in the assembly instructions. I didnt have a stim at the time. I'm going to go back and conduct those tests and then go from there.