What should the resistance between ground and the V+ from the car be?

My voltmeter says its a discontinuity, and is about 7.6Ohms, that would indicate a short on the PCB wouldn't it? Is there a common place to look after the isolated to220 chips?

 

Is your MS not working, not powering up?

Every time I've had a short, it's been the tip125's not being isolated from the heatsink bus-bar at the top of the MS... usually a hole in the mica.

 

It was working and powerup up last time I checked it, before I noticed these problems. I dropped it a while ago, and i couldn't get it to work for a few hours. Came good again.

It seems to be doing something funny tho, when it is working.

I would power it and turn it on, load megatune, and megatune would flash fuel pump on... fuel pump off... I found that reflashing the ecu would fix that and it would work again.

The ecu wasn't working yesterday. I measured the voltage on the board, 3.2v or something. Checked the psu, 3.2v. unplugged the psu from the megasquirt, 16v on the psu. You get the picture.

I'll check the TIP125s

another other ideas??

 

the flashing fuel pump means you have bad settings.

If it does that again, start up hyperterminal, and turn on the MS... and then look for the message that pops up in hyperterminal. That'll tell you for what area you have the settings wrong.

If the voltage regulator is only outputting 3.2v, it sounds like it might be dead...

If dropping it seems to have broken it, you may have also damaged the crystal on the board. Did you by chance use some PCB-safe RTV to "glue" the crystal to the board?

I can't really think of anything else that would be damaged from dropping.

Ken

 

I glued the cyrstall down with tarzans supergrip, yeah yeah i know a bit dodgey.

The output being low wasn't due to the voltage regulator, I think it was due to a short circuit, and the fact that the PSU isn't a regulated type.

I will do some checks later.

Thanks for your support maui