Thanks Jean

ronchinoy · Post by **ronchinoy** » Sat Feb 02, 2008 1:41 am

Was just looking at my stim and thinking 1 week down another 4-5 to go.
And the postman rang the bell with the new CPU.

Canand Post rocks.
I cant believe how fast it got here. And no hassles with customs either. USPS takes at least 4 weeks.

Just a small post to say thanks. For the super prompt service and suport.
Needless to say you guys Rock.

Lastly is anything I should chk before plugging in the new CPU.
looked for shorts and the voltage to the CPU is spot on at 5 volts.

Matt mentioned that this has happened in the past. Im sure there is some common boo-boo the users are making if we know what it is we can be careful not to repeat it.

Im also thinking of sealing the board base in epoxy. And making a little box for it. So there can be no doubts about a short.

I cant imagine how anybody could do a MS project without one of these stims.
A very Happy camper
Chinoy

Post by **jsmcortina** » Sat Feb 02, 2008 5:08 am

Glueing a piece of thick card or plastic to the bottom of the board to prevent any shorts might be a wise safety measure.

James

racingmini_mtl · Post by **racingmini_mtl** » Sat Feb 02, 2008 7:38 am

I'm glad it didn't take too long.

For more protection, you could also put a 1W 3.6V Zener diode (1N4729) between the 3.3V rail and the ground (banded side on the 3.3V side). This will make sure that if the voltage goes too high on the 3.3V rail, the Zener will limit how high this will go.

If the overvoltage is too much, the Zener will fail but it will still protect the CPU because it will short and the regulator will become hot but the regulator is protected against that. And replacing a diode is easier than replacing the CPU.

Jean

racingmini_mtl · Post by **racingmini_mtl** » Sat Feb 02, 2008 7:47 am

Just another point. When you say that the voltage is 5V do you mean 3.3V or are talking about the Megasquirt? The voltage must be no higher than 3.3V on any of the JimStim CPU pins.

Check at the socket that pins 1 and 3 have 3.3V and that pins 13 and 14 have between 0 and 3.3V depending on the position of the RPM pots. All the other pins should not have any voltage on them. Pins 15 and 16 might have a small voltage due to Q1 and Q2.

Jean

ronchinoy · Post by **ronchinoy** » Mon Feb 04, 2008 8:05 am

Super idea there to protect the CPU will implement it right away.
Diodes and regulator chips are easy to get and cheap.
Ive put the stim into a box and poured some epoxy we used to seal our circuits.

Also think I figured out what went wrong. While trying to install the PCB into the case I had moved R37 & R38 to the underside. When inserting the board R38 caught in the case. And one of the injector mosfets went without ground.

After getting the New CPU. Found that one injector bank was not firing.
Removed R38 & R37 and just jumpered the connection everything is back to working now. Its either this or a short.

Had a question.
The Stim has a 37 female connector. Is this provided for me to connect a connector . Or is it provided so that the stim can be plugged directly into MS
Ps: Sorry 3.5 v 5v was a typo.

racingmini_mtl · Post by **racingmini_mtl** » Mon Feb 04, 2008 2:13 pm

The JimStim's DB37 is intended to be used to connect the stim directly to the MS. You can use a cable if you want to as long as it's a direct pin-to-pin cable. Or you can use the screw terminals with wires.

Jean