'82 450 Igniter - Repair, Replace, or Make?

[Matchless]

Pete check your PM!

[john82q]

this bit leaps out at me,

Supply voltage: 12v ~ 13v
Coil "on" when G > 1.64v
Coil "off" when G < 1.43v ~1.44v
 

I think it possible pick up dosnt give quite a high enough pulse to switch it. thus why not firing every time.

Also worth remembering amplitude of the pulse will vary with the speed the of the cranking. (try kicking harder pete)


john

[pete]

Pete check your PM!

Got it Andre! Thanks

this bit leaps out at me,

Supply voltage: 12v ~ 13v
Coil "on" when G > 1.64v
Coil "off" when G < 1.43v ~1.44v
 

I think it possible pick up dosnt give quite a high enough pulse to switch it. thus why not firing every time.

Also worth remembering amplitude of the pulse will vary with the speed the of the cranking. (try kicking harder pete)


john

Makes sense John, and that's one of the reasons I'm wondering what's gonna happen with increased crank speed.

I definitely have more reading to do on Lou's various notes and more figuring to do as to why there's no spark at all when I introduce some bias.

I'll see what behaviour happens by just hooking up the second module tonight.

[pete]

Well, it was like banging my head against a brick wall again tonight, only I think that would be more satisfying than trying to figure this spark issue out

So, this is what I was playing with last night:



That's the circuit like the original non-biased CX650 that was actually giving me spark, but on every second revolution.

So I duplicated it for the left side as well tonight:



But there is no spark at all with both hooked up.

I went back and tried all the variations I could with the GS1000G diagram, the KZ550 diagram, and the CX650 diagram, although that's pretty much the same as the KZ550.

At the end it seems that with no bias, the voltage doesn't peak high enough to turn the coil on, meaning therefore it's always off and a spark is never generated.

Alternatively, it seems that every time I attach bias, I think it's staying in what Lou refers to as the "ambiguous" range, which means it doesn't know whether to turn the coil on or off, and therefore still not spark.

So right now I'm a little lost, except to note that if I set it up like the KZ550 or CX650 diagram with only the two diodes for bias (dropping the extra resistor so it's 1.4v), then plugging the ground wire in causes a spark on both plugs simultaneously. I'm not really sure what that means though.

I really thought I was getting a grip on Lou's notes today, but I think the missing piece really is the signal being generated from the pickup coils, which I somehow don't think is the 1.5v like John's seeing on his 1100.

I think the 60 - 80 ohms of the pickup coils compared to the couple of hundred that seems to be the case on all the others is making a large difference, but that's just a guess at this point in time.

One other thing I just thought of is that if the amplitude of the signal isn't as strong as the others, I might need an even higher bias, so if I could remember my theory from my college days I should be able to work out a different resistor value for what's in the GS1000G diagram as R2.

[Matchless]

Pete,
The resistor R1 is to limit the current and should not be changed. The bias voltage is determined by the drop across each diode. In the GS1000 method we added another 10 or 15 ohm resistor R2 to lift the bias voltage to 1.4V. If you do that, can you actually measure the 1.2V or 1.4V by which the ground has been lifted? You need to be sure that is actually happening. The pulse is then closer to the HEI triggering point.

You may find that if you go too high with the bias voltage the HEI may just stay on. If this is the case, have a look at using a transistor to drive the HEI, like Lou used in the last part of the notes for a points configuration HEI. The transistor is then triggered by the much smaller pulse from the pickup and it in turn generates a larger pulse to trigger the HEI. In fact just a little pulse amplifier.

You can find Lou here: http://www.kzrider.com/forum/4-elect...uestion#439185

His handle is louhvx on that forum. He may help you or give some advice.

[rustybronco]

What is voltage drop across the diodes? you could always substitute different diodes with a different drop.

[pete]

Pete,
The resistor R1 is to limit the current and should not be changed. The bias voltage is determined by the drop across each diode. In the GS1000 method we added another 10 or 15 ohm resistor R2 to lift the bias voltage to 1.4V. If you do that, can you actually measure the 1.2V or 1.4V by which the ground has been lifted? You need to be sure that is actually happening. The pulse is then closer to the HEI triggering point.

You may find that if you go too high with the bias voltage the HEI may just stay on. If this is the case, have a look at using a transistor to drive the HEI, like Lou used in the last part of the notes for a points configuration HEI. The transistor is then triggered by the much smaller pulse from the pickup and it in turn generates a larger pulse to trigger the HEI. In fact just a little pulse amplifier.

You can find Lou here: http://www.kzrider.com/forum/4-elect...uestion#439185

His handle is louhvx on that forum. He may help you or give some advice.

Thanks Andre, I'm referring to changing R2 rather than R1. With just the diodes, I get about 1.4v bias, but adding a 15 ohm is a bit over 1.5v and a 10 ohm is about 1.5v, so I figured going up to 20 ohms or so may help.

Alternatively, as you say it may just end up with the coil permanently on.

I haven't read through the points version as yet and was concentrating on the others, however thinking back to the schematic you have for the 450 ignitor, there does seem to be a few transistors in that from memory, so I'm wondering if they did in fact include an amplifier style circuit in there.

I've tried to avoid attempting to hassle Lou so far as I'm a complete stranger to him from a completely different forum, but I may yet have to resort to asking for some advice if he's interested... I just don't like imposing on people.

[pete]

What is voltage drop across the diodes? you could always substitute different diodes with a different drop.

Very true Dale! As in my reply to Andre, at the moment 1.4v across both. Adding a third will be far too high (2.1v) which is why I thought increasing the R2 value a little may be enough.

The more I think about it though, the more I'm thinking Andre's comment about the amplifier may be right.

I'm sure the lower resistance value compared to the others Lou has designed circuits for will make a significant difference to the amplitude of the signal being generated...

I think I'm going to need to take John up on his offer of the use of his scope...

[rustybronco]

I think I'm going to need to take John up on his offer of the use of his scope...

A wise choice.

[pete]

I sometimes wonder where my brain is...

I have at my disposal two schematics suitable for the 450's, one is an unverified schematic that should reflect the OEM ignitor, and the second is one done up by someone as a replacement for the OEM one.

Both of these schematics clearly show the black/white common wire connected to frame ground with the brown and green/white wire being used for signal generation and definitely seem to have what I interpret to be either bias or signal amplification applied.

I was never brilliant with transistor theory in college, so I'm not 100% certain on which of the above is the case, amplification or bias.

Either way, my next try will be to ground the black/white and connect the brown and green/white to G on each module and try that both with and without a bias, but I suspect it should be a 1.4v bias with both diodes.

Fingers crossed...

[pete]

I got a spare 15 minutes just now to try my theory. That was a bust.

Grounded black/white, brown and green/white to G on each module, and no bias = no spark.

Added 1.4v bias to W on each module = no spark.

Added 1.5v bias to W on each module = no spark.

I'm not surprised, but had to try it.

I should be able to borrow John's scope on Sunday or next week one evening. John, thanks again and I shouldn't need it for long at all.

[pete]

I went round to meet John today (nice bloke) and borrow his scope to do some further analysis. As it turns out, he actually works for the same company as my house mate but in a different location. Small world ain't it?

We had a good chat and one thing that came to surface is the likelihood that the OEM ignitor works off a positive signal rather than a negative signal which the HEI module requires.

Unfortunately this is one area that my repro factory workshop manual doesn't go into in detail and it only briefly mentions that there's transistorised ignition.

However, both the Clymer and Haynes manuals indicate that connecting the positive lead of a multimeter to the signal generator input of the ignitor should cause a spark, so a positive signal is definitely what fires the spark on the OEM ignitor which will need to be inverted to a negative signal by a transistor.

So, I got some time tonight to duck into the garage and do some testing, but unfortunately I can only turn the crank by hand at the moment, so the results aren't 100% yet.

Once I get a chance to get some oil in ready for the first start (hopefully this week), I'll get it cranking and see what the output's like then. I want to do this very soon as I don't want to hold onto John's scope for too long.

So, here's the crappy photos I have at the moment, and it indicates somewhere around 30 - 40mV generated:





As you can see, cranking by hand doesn't give a nice output like I'd expect to see while the motor's running, but that's what I'll have to work with for the moment.

I was going to attempt to hook up a transistor tonight using some of Lou's other diagrams for reference and also going by what John was saying today, but I lucked out on resistors.

I have probably about 50 resistors left over from my college days, but not one single 47K ohm resistor in sight, and the closest I could probably do is 5 x 10K ohms in series to give me 50K which will probably limit the current too much to turn the transistor on, although I haven't searched for the maths to work that out yet.

I do have several BC547 transistors though, so I should be able to duck into Dick Smiths or Jaycar at some point soon and pick up some 47K ohm resistors.

So, in a nutshell, I need to amplify the signal quite alot to get it to the range where it will trigger the HEI module, and I need to invert the signal also.

One other thing we discussed today is that adding transistors will probably result in a small timing variation from OEM as turning them on will invariably cause a small delay, so I may end up needing to rotate the signal generator plate a little to compensate for this.

First things first though, time to get some spark happening!

I'll nut out a diagram of what I need to do soon too so I have something to work with and for others to give feedback on.

[Nessism]

Pete,

You can download a factory suzuki manual from basscliff, although he may not have the 450 version, but for the purpose of how the ignition works I'm pretty certain they are all the same.

I checked the 550 manual and it says the signal generators make an AC current (the rotor is a magnetic) which then triggers the ignitor. I don't know how the HEI operates but it's hard to imaging it operates differently (but what do I know).

Edit: fixed name

[pete]

Don,

You can download a factory suzuki manual from basscliff, although he may not have the 450 version, but for the purpose of how the ignition works I'm pretty certain they are all the same.

I checked the 550 manual and it says the signal generators make an AC current (the rotor is a magnetic) which then triggers the ignitor. I don't know how the HEI operates but it's hard to imaging it operates differently (but what do I know).

Thanks Ed, I completely forgot to mention that my testing tonight was with the black/white common wire to both coils grounded, the same as the OEM hook up.

I tried it without being grounded, but didn't seem to get any output on the scope whatsoever.

I really need to get it cranking with the starter to get a constant signal to be 100% sure of what's going on.

The HEI module (going by the write up on Lou's site) requires 1.63 - 1.65v to turn the coil "on", and then requires 1.37 - 1.48v to turn the coil "off" again and fire the spark.

Oh, and it's Pete, not Don And I still take no offense

[Nessism]

Damn it Pete, can't believe I did the same thing again with your name. So sorry!!!!!!! Guess you Ausi's all look the same (on the internet).