[jamesobrady]

Hey all.
Now, not to be confused with an ECU that holds fuel mapping-a CDI is the modern version of a distributor. Carb models only.
Afaik it takes a signal from 4 coils in the crank position sensor, which tells it which ignition coil to send voltage to.

Repairing a blown cdi is not rocket science, but without being able to test it and troubleshoot the fault it can be a nightmare.
A recent delve into the world of getting them overhauled got us quotes of 2-300 euro from places in the uk and holland. And shipping and waiting times on top of that. The resisters, capacitors, diodes and transisters that need to be replaced in most cases can be had from maplins/radionics for about 80euro all-in. If you can solder, you can fix it.

What Im trying to determine is, how to test one reliably without an oscilloscope. Im starting from the possibly basic assumption that all we need to do is input a Dc voltage on one pin, and look for an output on another.

Now, what im trying to figure out is what voltage that signal needs to be, how often it needs to be given, if it gets amplified or not in the cdi, and what the output signal should look like.

I have a variable dc power supply, and setting up a square wave should be easy enough using a relay.
Any suggestions/ideas/experience very welcome.

This post has been edited by jamesobrady: 20 October 2009 - 06:56 PM

[jamesobrady]

Jsut for anyone who is interested on this, what im doing here is a lot of work/hassle to troubleshoot an old cdi.
We were lucky enough to already have found a cheap replacement on ebay, but in general the Vmax cdi's are on offer for hundreds of dollars.
An alternative that I was looking into years ago on the 250 bandit was the megasquirt ecu kit for 200dollars.
Its essentially a kit you solder together and plug into your bike in-lieu of your cdi/ecu. You can control ignition timing/advance/retard and also fuel mapping/injector timing. Aside from that...its a full engine monitoring/recording box so you can see in real time what all your sensors etc are doing via a laptop or pda.

http://www.diyautotu....htm#whatheckms

Slso...how to turbo a fireblade engine (893blade)
http://www.locostbui....php?tid=114119

This post has been edited by jamesobrady: 22 October 2009 - 06:42 PM

[Zx10 Rick]

[

http://www.diyautotu....htm#whatheckms

Slso...how to turbo a fireblade engine (893blade)
http://www.locostbui....php?tid=114119
[/quote]





Me likey the turbo talk........
Check this one out undefined.When you get onto the main page click Infoboard on the right, you will see OSS Members projects, scroll down to the Phat Ass title by Yantoshi. Unbelivable build, starts the turbo about page 25... Serious stuff..

made a balls of the link...

This post has been edited by Zx10 Rick: 22 October 2009 - 07:02 PM

[jamesobrady]

Jaysus that Turbo could do with a bit of curust
I like it to a point....Some class engineering on bits, and then it's totally let down(to my eyes) with some stuff. Some really intricate and time consuming milling gone into that build !!

[galwaytt]

excellent thread, been a while since I dusted off those cobwebs.

Fwiw, you're correct on the CDI output - it's a lot more than 12v, and ign coils fitted to CDI engines have different primary/secondary ratios to those on conventional 'points' ones, to allow for it. This is one reason why CDI is popular on small engines, high outputs for starting on engines with small - or no - alternators/generators. Gives nice fat spark for starting and low speed. Porsche 911's, aircooled, use the exact same principle.

So, if testing a train of components, you may need to have matching components e.g. coils, sensors etc, otherwise you may not actually see a true result.

Always wanted to do what you're doing, but never got around to it ! No point now, I'll just sit back and wait for your results.......

'sfunny, got asked to look at a Boyer Bransden nightmare ign box on a Bonneville today. 6v coils, in series, postive earth.......LOLOL.......what were they thinking.......?

This post has been edited by galwaytt: 23 October 2009 - 10:25 PM

[echomadman]

Hey James, for any bandit cdi, or any old circuit board like that its the electrolytic Capacitors that are the problem 90% of the time. there used to be a thread on it on banditalley back in the day.

[jamesobrady]

echomadman, on Dec 22 2009, 07:50 PM, said:

Hey James, for any bandit cdi, or any old circuit board like that its the electrolytic Capacitors that are the problem 90% of the time. there used to be a thread on it on banditalley back in the day.

I remember that !! Made me go and buy a spare one on ebay so it did.

[echomadman]

oops double post

This post has been edited by echomadman: 22 December 2009 - 07:56 PM

[jamesobrady]

echomadman, on Dec 22 2009, 07:55 PM, said:

oops double post

I remember that !! Made me go and buy a spare one on ebay so it did.
EDIT: DAMN-foiled.

This post has been edited by jamesobrady: 22 December 2009 - 07:56 PM

[jamesobrady]

Bit of an update here on this for anyone who might be interested as iI've had to spend the last week reading into it....lol.
Im in Lima, with what I thought was a blown CDI....in actual fact its a blown TDI.

The difference is, a Cdi is a capacitor discharge ignition, and a TDI is a Transister discharge ignition.
A CDI puts out large voltage on teh low tension side, as noted before, which is then stepped up again by a coil pack to huge voltages to jump the spark gap.
A TDI interrupts the 12V to a coil pack on the low tension side, which causes it to "collapse" and fire off huge voltage to jump the spark gap.

A CDI is powered from a set of coils on the alternator stator.
A Tdi is powered from the battery, or the alternator through the regulator/rectifier.

A CDI can kill, a TDI can't.

So.....my bike, and the Vmax i was working on use TDI's, older bikes use CDI's.

Another thing i've learned is, on the likes of the tenere, it uses one coil to fire two plugs..so its a "wasted spark" syste, as one plug is sparking away even though it isnt needed to. The signal for that to happen, is when a small magnet on the rotor on the crank passes a pickup coil, and induces a small voltage into the Tdi. That works fine for a 180deg system,where the pistons are always 180deg apart, one at top-dead-centre, and the other at bottom-dead-centre. On a bike with more than one piston, and a different configuration, like the 2 cylinder tdm engine...almost the same design as the Tenere, but a 270deg firing order, there are two magnets on the rotor, and possibly 2 pickups(not entirely sure on that).

Anyway.....

When we were playing with my mates Vmax tdi, we took it apart thinking the transisters were duff, and replaced them, I took pictures of it at the time, but forgot about it with one thing and another (building a cnc controlled wood router machine,taking redundancy, and playing computer games while eating toasted sandwiches for 6 months...in that order). As it turned out long-term, the box was fine to begin with, and a weird sidestand switch was his problem....the good news is it still worked after we took it apart and replaced transisters and capacitors The bad news is there was no explosions
So....blown Tdi now on my bike..and we are up to date in the riveting world of this thread
Stay tuned for the repair if I bring the bike back to Ireland...the other option is stay tuned for the video of it being set on fire and pushed off a cliff.

Looking at everything, getting to the point of testing an old Tdi,which was the point of the thread at the start, should be easy enough. Will revisit that idea when I get home and try design a test rig that can be easily made.

fcuking Yamahas

This post has been edited by jamesobrady: 28 June 2011 - 04:29 AM

[proinnsias]

Are soldering irons, multimeters and transistors that expensive in Lima ?

If you can wait for postage : dealextreme.com are good for most bits for toys

P

[jamesobrady]

proinnsias, on 28 June 2011 - 09:54 AM, said:

Are soldering irons, multimeters and transistors that expensive in Lima ?

If you can wait for postage : dealextreme.com are good for most bits for toys

P

Not really P, 2 transisters, and getting all the capactiors replaced in the tdi today cost me 22soles, or just over 5euro.
Had to cut it open myself with a hacksaw....and in any case it hasnt fixed it. If nothing else, i now KNOW i need a new tdi