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3MA CDI > 3MA project's > 3MA-00 CDI

Bought a USB Hantek oscilloscope for better measurements and understanding from the 3MA-CDI

First thing to know is the behavior of the oem IC.
There for I soldered some wires at the incoming and outgoing signals and two mass wires fore the oscilloscope probes

So now I can measure the incoming and out going ignition signals on the IC

And I can measure the incoming and out going ignition signals without IC

First thing to measure is the signals without IC and see what the signals are.
Here we have measurements from pickup signal wire (yellow) vs incoming pickup signal IC (green)
(Signals are as expected)

One off the discovered thinks is, that when the rpm is rising more than 55HZ the pickup signal (falling edge) is getting a second pulse (probably a noise problem) you also see that Yamaha has used the rising edge for the tricker signal

Of course the IC can't use the pickup pulse signal (as it comes) directly from the pickup it self.
It need to be converted to a digital signal, and that is what toshiba T2333 is doing.

So pickup signal is coming on pin 6 on the T2333 and is going out on pin 4 ready for the IC.

Here you have (pin 4) of the T2333 (green) compared with the incoming signal in the IC (pin 22) (yellow)

Now we know that this all, lets see what changes when we have the IC placed

Measuring at the incoming pickup signal (pin 22) and the outgoing ignition signal (pin 13)
Second discovery is that the incoming pickup signal is changed by turning at the TPS sensor

You see the pickup signal (green) has a small extra pulse, TPS at full throttle

Here you have the TPS closed

This sounds strange the only explanation I have (for the moment) is that the TPS sensor signal coming in on pin 35 at the IC. Is is sent through the IC to the T2333 where the pickup signal is changed in time length before it is send to the IC on pin 22.
(this needs further investigation)

Also discovered that the CDI is working without Any IC fitted.
Pickup signal is the same as ignition signal

Here is a Snapshot with no IC fitted.
Measured on the incoming wire pickup signal (white/black) vs ignition signal (orange wire)

11-10-2014

New measurements and thought about the CDI.

By reading more about ''how CDI's work'' found out that certain components needed more investigation.
Those are the:

-T2333
-Thyristor (gate)
-Capacitor

Small Combined information about the working off a CDI.

All CDI's uses a big capacitor, witch charges it self by the high voltage spools on the stator.
If that charged capacitor is pulled to mass that energy (pulse) is used for the orange wire witch goes to coil and tacho.
The Pulling to mass is done by a Thyristor (kinda super swish) witch can be controlled by it's ''gate'' connection.
To control the gate you need a correct signal that is generated from the T2333.

Lets see some signals

Lets start with the Tyristor.
(Here we have the gate signal)
To find out the thyristor connection wasn't that hard, the component got three pins.
-first pin> is directly to mass
-second pin> has the same signal as the Capacitor (is logical as it is connected at one side off the capacitor)
-third pin> is the gate pin witch is used to control the Thyristor like a swish

My logical thoughts where saying, I need to find a signal which is equally to the gate signal.
You will be surprised how much signal that are.

Lets start with a couple off interesting signals, compared with the Thyristor gate port

Here is a nice one.
Thyristor gate vs red stator spool charging wire. (used for capacitor charging)
Good to see is when the capacitor is discharging it self, the pulse is less high (as the energy is needed to charge the capacitor)

Here the Tyristor gate compared with the green charging capacitor spool wire, less spectacular but nice to see

Now we know how the Thyristor gate signal looks, I needed to find a signal witch can be used for that.
Knowing that the T2333 is generating a lot of signals, a good place to start finding usable signals

Got a few interesting one's.

T2333 pin two vs gate signal (green)
(block signal)

T2333 pin three vs gate (sinus signal)

Also interesting to see are the two usable gate signals from the T2333
Block signal vs sinus signal

Those two signals are equally (timing) to the outgoing signal off the IC

I was carried away by finding a usable gate signal, that I forgot the most logical one's
Logical would be IC outgoing signal vs gate signal.

Here we have the IC out going signal (as we thought it would be) compared with the gate signal
(It moves when RPM is rising)

Here we have the incoming IC signal (as we thought it would be) compared with the gate signal
(It stays steady will RPM is rising)

That is a very interesting thing, as how is it possible that the outgoing signal is slower as the gate signal.
That is a easy answer ''it can't''

What is this telling us,

Pin 13 on the IC is not a outgoing signal, but its the Incoming signal.
Pin 22 on the IC is not a incoming signal but its the  outgoing signal.

Knowing this, it all fits together.

Why was the pickup signal coming from the T2333 changeable when turning at the TPS sensor?
I mean how was it possible that the pickup signal was changing in the T2333 before it was going to the IC wile the TPS sensor is only coming in at the IC.
Simply it can't.
It was not the pickup signal I was measuring, but the outgoing signal. And logical, that can be changed by the IC when it received his TPS signal.

But way was I measuring on pin 22 a pickup signal, when no IC is connected. (wile no signal can be measured on pin 13)

That is still a question that needs further investigation. But think it has to do with the fact that the ignition is firing with no ic placed, measuring a pulse that is coming from Tyristor gate going to the T2333.
(as some components are connecting them together like resistors, and diodes)

More to come

13-10-14

It was difficult to understand way nothing could be measured on pin13 (incoming pickup signal) when no IC is placed.
From what I know now, looks like the IC is activating some kind of circuit witch allow the Pickup signal to follow his route.
If no IC is placed, it seems that the pickup route is blocked.

To find out what went wrong I followed the route from pin13 to where I would end.
We start with pin13 IC vs end diode (first element the route sees) you see exactly the same

Second measurement is signal before diode (measured over the element it self)
you see that the element is making some kind of peek on the block signal (way I don't know)

And finally the signal ends at pin4 from the T2333.
Here you see the signal from Pin4 till before diode at pin 13 IC
(signals are the same)

Looks like the T2333 is a very important component it handles the incoming pickup signal and convert it to a outgoing IC signal. Also it handles the outgoing IC signal to trigger the gate on the Tyristor.

I soldered a wire on pin 4 for the iCP12 to connect later

Later this day, found out that the signal is traveling until 5mm in front off the cdi.
Just on component seems to be between it

Because of all the wax/glue I couldn't see what it was.
After some fiddling around try to removing the wax, found it its a small diode.

Same like they have used on other parts off the CDI unit

Last peace off the puzzle is solved to.
Found out how it is working, the scope already told me but I didn't see it right

Here we have a snapshot of a stopped engine.
(Green) IC pin13
(yellow) pickup signal diode

Here you have a snapshot from a running engine.

You see it is moved
(green) is to 5V
(yellow) is to 5V

Explanation:

The IC on the CDI is giving a constant 5V signal on Pin13, the current is not blocked by the diode and can go trough the diode to follow its route.

The voltage of the pickup signal is constant 5V to, but can't go into the IC because it is protected by the Diode (one way direction)
Ones the pickup signal gives the mass point, the outgoing signal from pin13 can only follow it, and is pulled to mass to.
(That is giving the pulse the IC can work with)

Here a short movie how it is working

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