Jimstim problems, checking findings...

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Jimstim problems, checking findings...

Postby midas » Tue Sep 22, 2015 12:34 pm

Good evening!

I've just soldered up a JimStim V1.5 from a kit and connected it to the MS2 I've also just done to test. The stim passed all the tests in the manual and I've been trying to upload firmware to the MS2 this evening.

At first all seems well and then power to the MS2 is lost just about the point of flashing the MS2 CPU firmware across, at the same time the FP and FIDL LEDs light dimly and the F1 polyfuse gets very hot. A couple of minutes later I can rinse and repeat and go through the whole process again with the same results. There is no change in temperature of the U2 voltage regulator.

Going through the trouble-shooting guide I have removed the CPU and tried again, F1 again gets too hot to touch. Following that I have pulled D4 which I believe is the protection diode?

Powering up now has no effect on the polyfuse (CPU still removed from socket).

From reading the trouble shooting section it looks like the D4 (1N4729 Zener) has failed and needs replacing, I've got the orientation of the diode right on the board so how could this have failed? Is there somewhere specific I need to be looking for the cause or is it just a case of **** happens and every so often a duff one comes out of the packet?

Thanks in advance,

Rich
Last edited by midas on Tue Sep 22, 2015 2:42 pm, edited 1 time in total.
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Re: Jimstim problems, checking findings...

Postby racingmini_mtl » Tue Sep 22, 2015 1:26 pm

Did you do the troubleshooting tests with the MS2 connected or not? You should do them without the MS2 connected because a short on the MS2 board will also result in overheated components on the JimStim. So confirm how you performed the tests before going any further.

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Re: Jimstim problems, checking findings...

Postby midas » Tue Sep 22, 2015 1:27 pm

racingmini_mtl wrote:Did you do the troubleshooting tests with the MS2 connected or not? You should do them without the MS2 connected because a short on the MS2 board will also result in overheated components on the JimStim. So confirm how you performed the tests before going any further.

Jean


Hi Jean,

Yes it was disconnected from the MS2.

Rich
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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 4:22 am

Any ideas where I should be looking for faults? I've ordered another 10 diodes but would rather end up with 9 spare ones.
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Re: Jimstim problems, checking findings...

Postby DaveEFI » Wed Sep 23, 2015 5:23 am

Is there approx 3v on the output of the voltage regulator on the JimStim?
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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 5:40 am

DaveEFI wrote:Is there approx 3v on the output of the voltage regulator on the JimStim?


Assuming that is the leg of the regulator nearest the edge of the board? It's showing 3.28v there.

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Re: Jimstim problems, checking findings...

Postby racingmini_mtl » Wed Sep 23, 2015 7:12 am

You just have had an issue with a temporary short or a static discharge. Since the bottom of the board has many exposed solder joints that run at different voltages from 3.3V to 12V, if the board comes into contact with a conductive object you can have 12V shorted to the 3.3V rail. If this happens even for a very short time, the diode is very likely to be damaged.

So if you get 3.3V without the diode, there is likely no issue with the board and you can simply install a new one. Make sure that the CPU has not been also affected once you've replaced the diode.

Jean
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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 8:46 am

racingmini_mtl wrote:You just have had an issue with a temporary short or a static discharge. Since the bottom of the board has many exposed solder joints that run at different voltages from 3.3V to 12V, if the board comes into contact with a conductive object you can have 12V shorted to the 3.3V rail. If this happens even for a very short time, the diode is very likely to be damaged.

So if you get 3.3V without the diode, there is likely no issue with the board and you can simply install a new one. Make sure that the CPU has not been also affected once you've replaced the diode.

Jean


Cool, will do, thank you.

The whole board feels rather exposed, but I can see it isn't an easy thing to encapsulate easily whilst retaining functionality. I think I may look at putting in some sort of support that doesn't leave the stim hanging from the 37 way connector. I suppose a block of foam would do the job just as well?

Rich
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Re: Jimstim problems, checking findings...

Postby racingmini_mtl » Wed Sep 23, 2015 9:02 am

Be careful with foam: it can give nasty static discharge if it's not the anti-static kind. A piece of cardboard attached to the bottom of the board would be a good insulator.

Another thing to remember is that the 12V from the power supply is still present at the jack (and its solder joint) even with the switch in the off position. So it is possible to short 12V to the 3.3V rail even with the switch off if the power supply is connected and live and the bottom of the board comes into contact with a conductive object. I've done that once by simply putting the Jimstim on the top of the MS case; it looked like a nice empty space at the time...

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Re: Jimstim problems, checking findings...

Postby DaveEFI » Wed Sep 23, 2015 9:22 am

midas wrote:


The whole board feels rather exposed, but I can see it isn't an easy thing to encapsulate easily whilst retaining functionality. I think I may look at putting in some sort of support that doesn't leave the stim hanging from the 37 way connector. I suppose a block of foam would do the job just as well?

Rich


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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 9:30 am

racingmini_mtl wrote:Be careful with foam: it can give nasty static discharge if it's not the anti-static kind. A piece of cardboard attached to the bottom of the board would be a good insulator.

Another thing to remember is that the 12V from the power supply is still present at the jack (and its solder joint) even with the switch in the off position. So it is possible to short 12V to the 3.3V rail even with the switch off if the power supply is connected and live and the bottom of the board comes into contact with a conductive object. I've done that once by simply putting the Jimstim on the top of the MS case; it looked like a nice empty space at the time...

Jean



I suspect this may be how it has happened, juggling with the MS2, laptop and stim while Alfie the dog did his best to sit on the soldering iron. All noted ref the foam.

Rich
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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 9:34 am

DaveEFI wrote:
midas wrote:


The whole board feels rather exposed, but I can see it isn't an easy thing to encapsulate easily whilst retaining functionality. I think I may look at putting in some sort of support that doesn't leave the stim hanging from the 37 way connector. I suppose a block of foam would do the job just as well?

Rich


Gaffer tape, as always, is your friend. :D


I'm trying to get away from cars held together with Gaffer tape, I feel I may fail in this respect.... :D
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Re: Jimstim problems, checking findings...

Postby AdeV » Wed Sep 23, 2015 9:49 am

midas wrote:
I suspect this may be how it has happened, juggling with the MS2, laptop and stim while Alfie the dog did his best to sit on the soldering iron. All noted ref the foam.



Hmm, I suspect Alfie the dog would only sit on the soldering iron the one time...... :shock:
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Re: Jimstim problems, checking findings...

Postby midas » Wed Sep 23, 2015 10:02 am

AdeV wrote:
midas wrote:
I suspect this may be how it has happened, juggling with the MS2, laptop and stim while Alfie the dog did his best to sit on the soldering iron. All noted ref the foam.



Hmm, I suspect Alfie the dog would only sit on the soldering iron the one time...... :shock:



I'm not so sure, he isn't the sharpest tool in the box.

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Re: Jimstim problems, checking findings...

Postby midas » Thu Sep 24, 2015 11:48 am

racingmini_mtl wrote:You just have had an issue with a temporary short or a static discharge. Since the bottom of the board has many exposed solder joints that run at different voltages from 3.3V to 12V, if the board comes into contact with a conductive object you can have 12V shorted to the 3.3V rail. If this happens even for a very short time, the diode is very likely to be damaged.

So if you get 3.3V without the diode, there is likely no issue with the board and you can simply install a new one. Make sure that the CPU has not been also affected once you've replaced the diode.

Jean


Well new diode in the board and all is running cool, until I put the CPU back in and power up, then the fuse heats up very quickly. I'm assuming the CPU is goosed?
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Re: Jimstim problems, checking findings...

Postby racingmini_mtl » Thu Sep 24, 2015 12:02 pm

midas wrote:I'm assuming the CPU is goosed?

Unfortunately yes.

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Re: Jimstim problems, checking findings...

Postby midas » Thu Sep 24, 2015 12:15 pm

racingmini_mtl wrote:
midas wrote:I'm assuming the CPU is goosed?

Unfortunately yes.

Jean


Deep joy! Something else to add to the growing order with jsmcortina.
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Re: Jimstim problems, checking findings...

Postby Chiburbian » Thu Oct 01, 2015 6:08 pm

I am posting this on his thread because I am having similar problems so we don't clutter up the forum but I am happy to make my own thread.

That said, here is where I am at.

I have a Jimstim 1.5 that has been working perfectly for two years. A couple weeks ago I started building a second MS 3.0 board and when it was at the testing phase I tested it for power etc. I got proper voltage everywhere I should get voltage.

I plugged up the MS3 CPU card and tried to power up the board to test communication. I got initial fuel pump light and my injectors fired priming pulse like they should, but within about four seconds ALL LED lights started to dim. Initially I thought it was my main board so I switched back to my original verified working 3.0 board but I had the same problem. At that point I disconnected the Jimstim and started diagnosing the issue. One thing I noticed very quickly was that I was getting only about 6 volts on my 12v header. I was also getting about 3 volts at my 5v header, and less at my 3 volt...

At this point I was getting: (db37 to the left, CPU chip removed)
12v at power plug
11v at top of polyfuse leg
3-6v at bottom of polyfuse leg
3-6v at 12v header
polyfuse and U2 getting very hot

The longer my Jimstim was powered up, the lower the voltages got. I let the board (polyfuse) cool for a day and tested voltage on the bottom leg of my polyfuse again. Approximately 6v and falling. I thought that perhaps my polyfuse had seen over voltage too often (my power supply was putting out like 16v at one point on accident) and was starting to degrade so I bought a selection of polyfuses from DIYautotune and installed one. Same problem. I Installed a new D1 diode and tried again. Still getting 6v or so. This is a jimstim that up until about two weeks ago has been working perfectly.

What is my next step? What other diodes or parts should I test/replace? Thanks!
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Re: Jimstim problems, checking findings...

Postby racingmini_mtl » Thu Oct 01, 2015 6:38 pm

Just to be clear, you have your JimStim not connected to the MS and without its CPU and it still gets hot?

The potentially problematic diode is not D1 but D4. Remove D4 and try again. If that solves the issue, replace D4. If you still have no heat and normal voltage after the replacement, re-install the CPU and check the voltage and that nothing gets hot. If that results in hot components, you need to also replace the CPU; if not, you're good to go.

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Re: Jimstim problems, checking findings...

Postby Chiburbian » Thu Oct 01, 2015 10:11 pm

If I can't get a 1N4729 locally are there any diodes that can be substituted? What are the flexible stats (for lack of a better term) if any?
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