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General Public Area >> PicoScope >> believable ht patterns.
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Message started by jez1342 on May 22nd, 2006 at 6:44am

Title: believable ht patterns.
Post by jez1342 on May 22nd, 2006 at 6:44am

i am having trouble with the patterns displayed for secondary ignition using the settings from the drop down automotive menu. the traces i get look nothing like the ones shown on the help file.
i've turned up the samples per trace and have tried block mode, and neither work any better.
are there a definitive bunch of settings that will universally work?
as a novice i find it difficult to trust the views i get on the scope. this knocks confidence and prevents me gaining any experience in diagnosing ht faults with the scope. i'ld like to simulate faults on a ht circuit but cant if i'm unable to believe  the waveforms/.

many thanks, jez.

in the UK. raining as usual!

Title: Re: believable ht patterns.
Post by Tom Roberts on May 22nd, 2006 at 7:53am
Hi Jez,

You don't mention what unit you are using.  How high you can turn up your samples depends on the unit you are using.  The amount of time you can put on the screen and maintain resolution is also affected.  

You also don't mention the application you are using your equipment on, or the test point.  This is also important.  Using good triggering also helps position the capture on the screen.

You will find many examples of secondary in this thread:

http://www.autonerdz.com/cgi/yabb2/YaBB.pl?board=picopub;action=display;num=1077528814;start=0#0

You may want to consider joining the Autonerdz support group.  Why?  Read what members say:

http://www.autonerdz.com/picousers.htm

You can see what this support system includes here:

http://www.autonerdz.com/picokit.htm#_DOH!__I

Of course, the support is included with all kits purchased from Autonerdz at no extra charge and does not require a subscription.

Our PicoScope forum support takes place in the members only area.

Title: Re: believable ht patterns.
Post by jez1342 on May 22nd, 2006 at 9:35am
hello tom, am using a pico3223 and am using the preloaded settings from the automotive dropdown screen.
i can't get a usefull pattern on plug or king leads. as i said, i new to scopes and find all the settings and other things you can adjust, slightly scary.

Title: Re: believable ht patterns.
Post by Tom Roberts on May 22nd, 2006 at 10:05am
Jez,

Yeah, it's a little overwhelming at first but you will see that the settings and adjustments allow you to control everything.  It's a good thing.   ;)

The example post above was using the old 212/3 unit.  The 3000 series are hundreds of times more powerful.  Your max samples can be turned up to 512,000.  Block mode is important for longer time bases.  Trigger off of the KV spike (5-6KV rising) and put in a negative 40% delay to move it over some.  Be sure to choose the correct KV range for the system.  -3 to 27KV is good for conventional negative fired systems like distributor.  With the pickup on the coil wire, you should be ready to go.  Now adjust the time base to parade a few events on the screen and zoom in to see the detail.

That's really about it.  Remember that the pattern off of a plug wire will only show the activity after the rotor.  There will be no coil oscillations, etc.

Here is a 3423 example from a Ford TFI 4 distributor system with PIP, SPOUT, Secondary and Primary Current:

http://www.autonerdz.com/flash/snaps.html

Turn on sound.   8)  During the movie, trigger was moved higher to capture only the snap KV.

Title: Re: believable ht patterns.
Post by jez1342 on May 23rd, 2006 at 11:30am
good morning! red face time. turned out that i had a broken ht pick-up D'oh. i've tried another one and the patterns look much better.
many thanks for your help
regards jez.

ps. the movie was cool. in a year or so, i may even understand half of it ;)

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