DB9 serial port not working, shorted cable (connections?)

[Arra]

So my ms1 v2.2 029y4a DB9 serial port stopped working because of faulty serial cable that shorted and burned (worked fine before with my straight cable and also with adapter). Ecu keeps all lights lighted when power is on, lights were for spark outputs and for warmup, fuel pump stopped working until i tried firmware download(maybe corrupted data) and installed jumper between boot pins, now pump runs all the time when powered... Update said download failed.

where should be db9 pins connected to. I checked one diagram that said db9 pin 7 should be straight connection to max232 pin 8 and db9 pin 8 should be straight connection to max232 pin 7. Those are only ones that didn't have connection in my case.

thank you.

[DaveEFI]

If the cable really did burn, the most likely thing to burn is the ground connection.

Refer to the V2.2 schematic for which pins in the DB9 are connected to what on the PCB. What you've given doesn't look right to me.

[Arra]

Yes cable did really burn.

I don't have mega with me right now, so i have to check all possible connections later. I referred to this info found from megamanual.com:

Check the continuity from the MAX232 to the DB9 pins:
DB9 pin #1: connects to MAX232 pin #16,
DB9 pin #2: connects to MAX232 pin #14,
DB9 pin #3: connects to MAX232 pin #13,
DB9 pin #4: connects to DB9 pin #6
DB9 pin #5: connects to MAX232 pin #15,
DB9 pin #6: connects to DB9 pin #4
DB9 pin #7: connects to MAX232 pin #8,
DB9 pin #8: connects to MAX232 pin #7,
DB9 pin #9: connects to VCC (5.0 Volts at the voltage regulator pin furthest from the DB9),
Each of the above connections should have 1.0 Ohms or less between the specified points when the MegaSquirt® is not powered.

As i said 7 and 8 pins didn't have any connection, everything else had like this info said.
What ground connections do you suspect? Checked board itself million times and no burn marks anywhere...

Thank you

[DaveEFI]

That looks to me like the connections on the V3 board The V2.2 is rather simpler.

http://www.bgsoflex.com/v22/megasquirt_ShemV2.2.pdf

Check Pins 5 and 9 are connected to ground.

[Arra]

thanks, ground seems fine. Should multi meter show connection trough those yellow 0.1 capacitors (c25, c26, c27, c28)??? In my case only c28 show connection through it...

[DaveEFI]

A small cap like that wouldn't normally show anything significant on a DVM. Unless it has failed short circuit - which these small ceramics can.

[Arra]

Took it to local engine management shop, at least voltage regulator and processor are ruined, most likely something else too... Waste of time and money trying to fix it, ordered already new mega since those are not that expensive

Thank you anyway for help.

[DaveEFI]

Took it to local engine management shop, at least voltage regulator and processor are ruined, most likely something else too... Waste of time and money trying to fix it, ordered already new mega since those are not that expensive

Thank you anyway for help.

IMHO, they'd not be able to tell the state of the processor without repairing the 5v supply. Unless they checked the processor in another good board.

In the UK at least, a broken MS will still have some value. If yours came up on Ebay here, I'd go to 50 gbp. And likely be outbid.

[Arra]

Fair enough

They changed new regulator for testing. And used some sort of fancy power supply machine.

They make, sell and tune their own 1000-2000 euros more high tec ecu, i'm sure they knew what they were doing, even if i dont understand(there are some reasons why i trust them and those are the reasons why they checked my ms for free)... ms1 v2.2 is quite simple machine for experts.

[DaveEFI]

All MS are reasonably simple to fault find - if you know them, and have spares on hand. And things like a Stim, etc. Any half competent tech can do this - but still has to learn about them. Same as any electronics. Sounds like they were familiar with MS.