No Trigger

Ask questions about DIY board assembly issues, fault finding and testing. (Covers all Megasquirt versions and board.)

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No Trigger

Postby eman911 » Mon Jun 19, 2017 6:54 am

MS2 v3.0 board
Batch fire
Ignition control
Factory Alfa Romeo Hall sensor in ditributor
DIYAutotune harness

My board is assembled and tested with a JimStim with no problems. I am in the process of setup and have everything working to spec so far except I receive no trigger signal from the dizzy. I have determined that the Hall sensor is working, it requires 12v power, and a pullup. I temped in a 10k pullup at the dizzy , provided 12v to the power lead cranked the motor and had alternating voltages on the sensor lead (12.5v- 3.5v). This leads me to believe the dizzy is functioning correctly.

I then removed the temporary pullup from the dizzy and installed it on the proto area with one leg to 12v at s12 on the board and the other leg to optoin. I cranked the motor and no signal to the ECM. Signal was good at the dizzy connection but no signal at the db37. I traced the wiring and found it to be good except pins 2 (shield ground) and 24 (Hall signal) were switched in the harness. I tested for signal from the dizzy at pin 2 and it was there (voltage was low due to the pullup being on the board and the board being disconnected). I switched the pins and guess what? No signal (Empty read, no data received from controller) on the high speed logger.

1. Is my pullup wired correctly?
2. If not what is the correct method?
3. If so what should I check next?

Thanks!
eman911
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 7:43 am

Quick update, I just realized my wiring diagram was for a 3.57 board, and the v3.0 wiring diagram in the assembly guide has me thoroughly confused. It illustrates a VR crank sensor but the text below describes the changes for a Hall sensor in a manner I cannot comprehend, so I will replace the wires as they were in the harness (pins 2 and 24) this will place the green (signal wire) on pin 2 and the shield (non insulated wire) on pin 24. The text states:

"To use a Hall sensor, optical sensor, or points trigger, you connect the signal to the same input pin (DB37 #24) as the VR sensor. You must ground the VR other lead of the sensor as well, and pin #7 is shown for this (though pin #2 can also be used). However, pin 7 is not a 'dedicated' or specialized ground for the VR sensor, it just happens to be a ground (the next revision of the PCB will have a dedicated ground for the VR circuit on DB37 pin #2, so use pin #2 if you think you might upgrade at any point)."

The Illustration in the assembly guide is not correct for the harness supplied, DIYAutotune's basic wiring diagram cannot be found I am getting more confused by the minute.

Can someone point me to the correct wiring diagram/pinout?
eman911
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Re: No Trigger

Postby billr » Mon Jun 19, 2017 11:08 am

Is the sensor signal still switching between 3.5V and 12.5V? I don't think 3.5V is low enough to be a valid "low". I would expect a good sensor to swing between 1V (or less) and within 1V of the pull-up source.
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 11:52 am

Bill- I will retest the signal voltages after I confirm I have my pullup wired correctly.

In the meantime I have verified my wiring to the Hall sensor using a thumbnail of the original DIYAutotune found on the Google, all was well there.
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 2:34 pm

Found this from DIY linked in an article from Grassroots Motorsports (DIY's site search is worthless):

PCBv3.0 Boards, MS-I or MS-II
Hall effect and optical sensors come in several varieties. Some send out a square wave signal on their own, going from 0 volts to 12 (or sometimes 5) volts and back to zero again. Others are what’s known as an open collector. An open collector signal works kind of like an electronic version of a set of breaker points. It toggles between floating (acting like it’s not connected to anything) and ground. If you put a volt meter on an open collector output, you won’t see anything happening. It would be like replacing the sensor with a light switch with one end connected to the MS tach input and the other end connected to ground: When the switch closes, the input is at zero volts, but when it’s open the input is not connected to anything at all, and with the normal circuit that is pretty much the same as zero volts again. To get a useable, voltage based signal, you’ll need what is known as a pull up resistor. VR sensors always put out an AC signal when the engine is running and do not need this mod.

A 1k (1000 ohms) 1/4 watt resistor is what you want.

Solder one end to the right side (non-band) end of D1, and solder a small piece of wire to the other end, heatshrink tube the resistor and solder joint to protect it, and solder the other end of the wire to the left leg (banded end) of D9. The left/right references are when looking down at the top of the board so that you can normally read the text, though you will probably do this mod on the bottom of the PCB…

I undid my previous attempt at an on board pullup and followed these directions except in regards to D1 as I have a jumper there per the assembly manual. The pullup is attached to the jumper. Still no ign signal and the "empty read" message from the logger.

What next?
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Re: No Trigger

Postby billr » Mon Jun 19, 2017 3:16 pm

Ignore, for now, the MS hardware and focus on just the Hall sensor in the dizzy. Apply power and ground to that sensor and let's get another reading on what the signal does when you rotate the dizzy. If the signal doesn't switch from nearly 0V to nearly the power supply voltage, nothing you do with the MS will be successful.
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 4:03 pm

With the distributor isolated from the MS unit and 12v, ground and a 1k pull up installed we cycle between .8v and .3v
as above but 10k pull up- 12v and 4v
with a 100k pull up- 11v and .9v
with a 1M pull up- 6v and .8v
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 6:42 pm

I ran the MS unit on the stim and was able to log a crank signal.

I installed a 100k pullup from s12c to D1 and got no signal.
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Re: No Trigger

Postby billr » Mon Jun 19, 2017 9:38 pm

Humor me. Repeat those tests on the sensor/dizzy using pull-down resistors.
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Re: No Trigger

Postby eman911 » Mon Jun 19, 2017 9:45 pm

Humor me and explain a pull down and how to wire it. My electronics knowledge is just enough to get me in trouble.
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Re: No Trigger

Postby billr » Mon Jun 19, 2017 10:01 pm

Instead of connecting a resistor between the signal wire and the power (12V) wire, you connect the resistor between the signal and ground. One way you are pulling the signal wire "up" to the up-high 12V, the other way pulling it "down" to the 0V ground.
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Re: No Trigger

Postby jsmcortina » Tue Jun 20, 2017 4:36 am

Please wire up your sensor and customise your board using the instructions in the current manuals. You can find them at the "Manuals" link above. (No need to go looking at random articles on the internet.)

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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Re: No Trigger

Postby eman911 » Tue Jun 20, 2017 5:10 am

Thanks Bill, I'll try that today.

James, I assembled the board and wired the car using the manuals above, unless you are being snarky in which case I winged it.
eman911
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Re: No Trigger

Postby jsmcortina » Tue Jun 20, 2017 5:36 am

You posted extracts from an out of date article on DIYAutoTune's website which uses the "Opto" input. Don't use that.

You talked about using a 10k pullup. The manual suggests using 470R to 1k as a pullup. 10k is likely too weak a pullup.
See this and following pages: http://www.msextra.com/doc/pdf/html/MS2V30_Hardware-3.4.pdf/MS2V30_Hardware-3.4-64.html

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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Re: No Trigger

Postby eman911 » Tue Jun 20, 2017 6:08 am

Lets go back.

I assembled the board using the assembly guide here:

http://www.megamanual.com/ms2/V3assemble.htm

Specifically for the input:

To install the Hall/optical input circuit (or points without a coil connection):
Install and solder R12 {390H-ND, 390 Ohm, ½ watt, orange-white-brown}. This is installed between the resistors you have just been installing and the CPU socket. This resistor should be mounted roughly 1/8" (3mm) above the surface of the PCB. Also, the value of this resistor may have to be changed if you trigger from the negative side of the coil depending on application - start with the supplied value, and if gets hot while the engine is running, then increase the value, in steps, up to 10K (like 470 Ohms, 560 Ohms, 680 Ohms, 1K, ...), or even more in some applications (consult the MegaSquirt Forums list for advice). However, do not adjust this resistor on assembly, unless you have a good reason to do so.
Install and solder R13 {4.7KEBK-ND, 4.7k, yellow-violet-red}. This is located 3 places close to the heat sink than R12 (which you just installed).
Install and solder C11 {399-2075-ND or 399-4326-ND, 0.01µF, 103 marking}. This installs at the top of the row of 'vertically' oriented capacitors above "Bowling" in the copyright notice.
Leave the C30 location empty - DO NOT jumper it.
If you have a Hall sensor or optical sensor, do not install D1, put a jumper in its place. It is located beside R12, further from the heat sink.
For most installations, diode D2 {1N4001DICT-ND, the marked 1N4001} is not needed. Do not install D2, install a jumper (made from a snipped off lead) in its place. It is located beside D1, closer to  the heat sink.
Note: this diode (D2) is needed only if the ignition system has a large offset bias - most systems do not have such a bias. So, to start, you can either solder in a jumper wire in this location, or, you can install the diode D2, and then install a jumper around the two leads of the diode - in effect shorting it out. The latter will allow you to snip the jumper later on if needed, putting the diode back in circuit. Solder the diode in observing the banded end as on the board, then solder a wire jumper across the diode itself.
Install/solder opto-isolator U3 {160-1300-5-ND, 4N25). This is located near the center of the PCB. If you have bought a socket (AE7300-ND or AE10021-ND ) for this component, solder it in place instead, then insert U3 into the socket. Observe the proper orientation (notch matches PCB - towards the heat sink, or dot for pin #1 which is the square pad on PCB at the notched end of the silk screen). If neither are there, hold the chip so that the writing is facing you and the right way around. Pin #1 is on the bottom left.
Leave the C12 location empty - DO NOT jumper it. This is located above "Bowling" in the copyright notice. This capacitor may need to be installed and/or the value increased if there are noise problems with the tach signal - values up to 0.1µF will work. The 0.001µF value is a good starting point.
If you later find you have an intermittent tach signal on the vehicle, but it doesn't work at all speeds or all temperatures in the car, check the Hall circuit modifications here: Hall input circuit mods

This input circuit is also used - with the modifications below - if you want to trigger off the negative side of the coil, since the points control the negative side of the coil's primary circuit. However, you can only trigger off the coil's negative terminal if you are NOT trying to control ignition timing. Do either 50a or 50b, not both.



Should I have done it differently?
eman911
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Re: No Trigger

Postby jsmcortina » Tue Jun 20, 2017 8:30 am

Yes, you should read the current manuals.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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Re: No Trigger

Postby eman911 » Tue Jun 20, 2017 2:51 pm

I have made the appropriate changes to the board to match the latest manual and have a couple of questions:

1. Under Hall/ Geartooth/ Logic/ Optical: c) Install a 1k resistor (any value 470R - 2k2 is likely OK) in the proto area. Connect one end to the 5V hole and
join the other end to VRIN with a jumper wire.
I assume this is the pull up resistor for the Hall sensor. If so my Hall sensor uses 12v, should the pull up then also be 12v?
I also assume that 560 ohm 1/2w would be adequate.
eman911
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Re: No Trigger

Postby jsmcortina » Tue Jun 20, 2017 3:08 pm

eman911 wrote:I assume this is the pull up resistor for the Hall sensor. If so my Hall sensor uses 12v, should the pull up then also be 12v?

No, the pullup should go to 5V.
I also assume that 560 ohm 1/2w would be adequate.

That's ok, 1/4W or 1/8W would be fine.

James
I can supply, repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

My Success story: viewtopic.php?f=104&t=34277
MSEXTRA documentation at: http://www.msextra.com/doc/index.html
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Re: No Trigger

Postby eman911 » Tue Jun 20, 2017 4:17 pm

Assembled as above and tested on a JimStim, everthing works as it should.

Installed back in the car, no crank signal and "empty read" from the logger.

Additional info:
ms2Extra 3.4.2
MSQ below
Attachments
2017-06-20_18.16.09.msq
(117.95 KiB) Downloaded 2 times
eman911
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Re: No Trigger

Postby eman911 » Tue Jun 20, 2017 5:52 pm

Update:

I found a broken (or nearly broken) ground at the dizzy. Will repair and retest tomorrow.
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