No rpm signal MS3X V3.0

[Nmcilwain]

Ok great , it may take me a little while but I'll report back soon.

[Nmcilwain]

OK, let's try to dig into this.

1) remove the JimStim from the MS and set the jumpers as shown in the attached photo. Note that there are just two jumpers there, one to set the primary tach to VR and one to connect that output to a 12V pull-up. Set the DIP switches to #3 "on", all others off; that will be for "36-1". Turn both the fine and coarse rpm pots on the Stim full CCW.

2) Connect the JimStim to power, 12V would be handiest but not essential, and power it up.

3) Connect a voltmeter between and pin 24 of the DB37 connector. You can either connect at the DB37, or on the 19-pin header, or at the 10-position terminal strip just behind the DB37; whichever is easiest for you. Set the voltmeter for AC volts.

4) with the JimStim rpm pots full CCW you should read about 0 VAC. When the coarse pot is turned CW the voltage should quickly jump up to about half of your "12V" power supply. With mine, supplying 12.9 V, I first see 6.70 VAC on pin 24. As you turn the coarse pot full CW the voltage at pin 24 should stay about the same, mine drops to 5.87 VAC. Your voltage there may stay constant or even rise because most DVMs, mine included, are "tuned" to read correct rms voltage for a 60Hz sine wave. The output at the JimStim pin 24 is a square wave, and not a perfect one, and frequency is varying as you turn the coarse pot; not 60 Hz in most cases.

This is all to ensure there is a good signal coming out of the JimStim, before diving into the MS. Note that the jumpers I ask for are different than shown before, and only enable the CKP signal. That is not to say the other info is wrong, just that I know this works and would like to stick with it as I try to help you.

If you do find the proper AC signal there on pin 24, then reconnect the JimStim to the MS, set the trigger mode in TS for "36-1", set both pots on the MS mainboard full CCW, and see if you now get an rpm in TS.

Ok I did not get the voltage on pin 24. I even changed over to a 12v power supply. I may go and borrow another meter. Feel pretty sure I followed your instructions.

[billr]

OK, just checking...

You had the meter set for reading AC volts?
There was virtually zero VAC, no matter how you had the "coarse" rpm pot turned?

How about posting another picture of the JimStim, showing the jumpers. It's sounding like we need to trouble-shoot your JimStim, there may be no problem with the MS.

[Nmcilwain]

Well it stayed the same no matter what I did on the rpm pods.

IMG_0479.JPG (419.27 KiB) Viewed 418 times

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[billr]

Well, I'm convinced the JimStim is faulty, that's the immediate problem. Post over-all pictures of the JimStim, both sides of the board.

Jean B: should we open a new thread in your jbperf forum, or keep going here?

[racingmini_mtl]

AC or DC voltage won't change with RPM on the JimStim. You should see AC voltage but not with a floating output. You have to connect the JimStim (or only the tach signal) so that it's not floating. Or check the DC or AC voltage on the other side of the output capacitor (C3 on the side closest to the O2 pot); this will work with a floating output, i.e., with the JimStim not connected to the MS. Put both RPM pots at around the middle of the travel to make sure you have some RPM.

Jean

EDIT: Please note that I haven't gone through the entire posting but only the last few posts. Also there is a troubleshooting section on the web page that tells you how to check the RPM output: http://www.jbperf.com/JimStim/JimStim_v ... ml#testing

[billr]

The JimStim output did have a load on it (not floating), R22 was connected to 12V via the jumper on JP14. Agreed, the output amplitude does not change appreciably with frequency (rpm), it looks stable on a scope; however, my old DMM (Fluke 77) doesn't read peak-to-peak or even true rms. AC accuracy for it is only specified for the 45 Hz to 1 kHz range, and only for a true sine wave. I expect the OP's meter is similarly limited, and wanted to warn the the voltage read may not stay deadly stable.

I'll be studying info on the JimStim, starting with the link just posted, but am still wondering if further discussion would be more appropriate at the jbperf site.

OK, let's see if the JimStim passes the test in that link, where the output is connected to drive one of the LEDs on the Jim Stim. My understanding is that test was done when the JimStim was first built, but do it again.

[billr]

Well, my apologies to Jean and the OP; that R22 is not a load on the pin 24 output as it is before the capacitor that I directed the OP to select with the JP14 jumper (simulating VR). Strangely, I wasn't seeing that when looking at the schematic, but realized it this morning laying in bed, "picturing" the schematic in my mind. Still, the input impedance of my scope and DMM was enough to load the output and give good readings. After seeing that, I dismissed the need for an external load, to keep the setup simple, and later convinced myself that R22 was doing it...

Back to the thread: do the LED check or check voltage at pin 24 with the jumper in the lower position, simulating Hall.

[MegaMicra]

Try this check to see if you have an output.
Put all the switches to off and remove the jumpers. Turn rpm course and fine all the way acw.
Attach wire jumpers from 12v header pin to pin 9 from the right of that row of 10 pins and connect another wire from primary tach pin nearest the pots to pin 10 from the right of that row.
Power up the Jimstim and turn the fine rpm pot cw. The iac2 led should start to flash.




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[Nmcilwain]

Guys thank you for all of the help . I am sending the MS3x and JimStim to Peter Florance to check it for me . I was having too many issues and I really was questioning myself if I was able to test correctly. I was afraid I was giving bad info and making it harder on everyone trying to help. I will report back as soon as I find out .

[MegaMicra]

OK no worries. Don't forget to let us know what was up. I'm sure it's nothing much.

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[Nmcilwain]

Ok guys Peter at PF Tuning said the Megasquirt checked out fine but the JimStim CPU was installed backwards which killed it and the tach out transistor.

[Nmcilwain]

Ok guys Peter at PF Tuning said the Megasquirt checked out fine but the JimStim CPU was installed backwards which killed it and the tach out transistor.

Which was my fault because I remember upgrading the CPU.

[MegaMicra]

That's great news. Glad it was an easy fix. If only your hand wasn't obscuring the Jimstim chip in that photo you posted we might have spotted it. haha.
Anyways at least you can get it back and start moving with your project, and also you've got a lot of info on how to setup, test, and use the Jimstim.

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[Nmcilwain]

That's great news. Glad it was an easy fix. If only your hand wasn't obscuring the Jimstim chip in that photo you posted we might have spotted it. haha.
Anyways at least you can get it back and start moving with your project, and also you've got a lot of info on how to setup, test, and use the Jimstim.

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Wow I didn't realize that in the photo ...haha