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Re:Easiest way to learn to use a scope?

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2 years 11 months ago #47996 by Live2Fish88
I have SDs book, but want to learn how to use my scope (autel scope) and be proficient in it. I don't know where to start or what to look at without causing damage to the tool or vehicle.

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2 years 11 months ago #47999 by ezimoto
Sure we'll all have different thoughts on this but my first thought for a novice would be to watch the excellent Verus training video's that Paul has.
If you go to the scope section he shows how to use the scope using a training board but you could do this on a car instead.
Doesn't matter that he's using a Verus as the overall concept applies to any scope. Make sure you have some decent back probes and stay away from high current until you're confident and have the right attenuators.
Have fun
Ezi
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2 years 11 months ago - 2 years 11 months ago #48000 by Andy.MacFadyen
Oscilloscopes have very high input resistance - 1 million Ohms so just connecting a single channel to anything on a car won't damage anything on a car.
BUT you have to watch out for a couple of things first of all all the channel ground connectections on all but some very expensive scopes are wired in common.
This means if you are accidentally connect a ground to battery +12 live you end up with what is called a ground loop effectively a complete short circuit and a huge current will try to flow through the ground wires circuit the scope. This is why for most automotive work only a single ground is used
A ground loop can also burn out a driver in an engine computer or module --- so taground wireske care with

The other thing you have to watch out for is high voltage spikes from inductors such as coil pack primary corcuits and fuel injectors damaging the input circuit of the scope. The more expensive automotive scopes are designed to be protected against this but cheaper scopes and labscopes need an attenuator beteween the scope and the test lead. Attenuators usually come in x10, x20, and x100 types, for automotive work x20 is normally chosen for looking at ignition primary voltage but most non-automotive labscopes only have x10, x100 and x1000 scales.

For the kilo voltages of the ignition secondary a special capacitive or inductive probe is required

" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)



Last edit: 2 years 11 months ago by Andy.MacFadyen.
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2 years 11 months ago #48017 by stevieturbo
What do you want to test ?

best way to learn is by doing..

A few simple tests I've done on a recent scope I got. And none even touching a vehicle, just messing about with some stuff I had either at home or in the workshop.. So you're at pretty much zero risk of harming anything and you can do it on the bench.

1. Small 12v battery, and 50w halogen spotlight (or headlight I guess ). You can scope the 12v side, with a current clamp you can record current, and this is also handy to actually verify readings you are seeing and any sensor calibrations within the software.
I verified this against a standalone current clamp. And to see higher readings I tried 8 and 10 windings through the clamps, so a 5A load will actually appear as 50A ( with 10 loops through the clamp...but you can try 1, or however many just to see the difference )
And in this case, the little Hantek clamp only reads to 40A...which again became apparent from the test, even though the CC-65 part number suggests it should probably do 65A.
It was also interesting to see how high the current spiked when powering it up ( again at 10x due to the multiple windings )
I also tried another 100A/1000A clamp bought which seems a little more temperamental, but it does work ok.

2. I have a little 6/12v battery tester that places a load on a battery to determine it's current Ah rating. I wanted to see how it worked. So again, recording battery voltage and current applied when under test.
Over a period of 60ms it applies a 5A load 25 times. This can be seen as well as the battery voltage drop during the test.

3. With a signal generator ( crank/cam sim ), simple scope readings of that waveform at various rpm.
Funny thing is there...the 36-1 pattern the generator develops, in 36-1 crank/single tooth cam, it actually has some overlap on the missing tooth, so every other missing tooth isn't quite correct, it's a little long.
The above is very cheap/easy, arduino nano based and can do a number of crank/cam patterns in square wave.

4. Same mode as above, with a little 10k pot wired to a 5v supply ( or 12v would do ), it gives you a simple variable voltage to play with.
Or if you have a 5v bench supply you can start rigging up some OEM sensors and playing with them to test their outputs and behaviours.

But Scanner Danners book is a good place to start, AES Wave sell a paperback version which is handier for reference than a computer version..
www.aeswave.com/Engine-Performance-Diagn...nerDanner-p9277.html

This is another
www.amazon.co.uk/Automotive-Oscilloscope...toakes/dp/0992949262
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2 years 11 months ago #48028 by Tutti57
I have a uscope and a hantek. What I started to do was use the uscope instead of grabbing my meter, just to get comfortable setting the scales up, and because that scope is very quick to set up. Then I started using it anytime I was looking at a circuit the was pwm, like a blower motor. Seeing the changes in duty cycle as you change the fan speed.

I also use the bench testing approach. I'd keep failed components and bench test them with a current clamp and a battery. I can usually find known good components to test in one of our parts changers garbage cans.

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2 years 11 months ago #48041 by Chad
A wise man once said, "Scope all things."

"Knowledge is a weapon. Arm yourself, well, before going to do battle."
"Understanding a question is half an answer."

I have learned more by being wrong, than I have by being right. :-)

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