Advice re oscilloscope choice for automotive diagnostics?

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Basil
Posts: 36
Joined: Fri Sep 16, 2011 2:28 pm

Advice re oscilloscope choice for automotive diagnostics?

Post by Basil »

I have been using a USB scope but realise just how little I know about scopes and feel the need to back track and get some basic general info before committing to a costly purchase of a bench type scope. I hope someone can find a few minutes to guide me here, please?

I am currently using a Dataman USB scope http://www.dataman.com/oscilloscopes/da ... scope.html for basic automotive diagnostic work, looking at injector and coil waveforms, reading the outputs of cam and crank sensors, both Hall effect and magnetic, watching thermistor voltage outputs, and looking at throttle position sensor outputs, etcetera. It is not an automotive specific device like, for example, some of the Picoscopes, but this has perhaps worked to my advantage, as rather than pushing on screen menu buttons to set up scaling automatically, I have had to think about what I am trying to measure and do it manually. It has helped me get a basic grasp of signal levels.

I now find carrying a laptop around and the Dataman scope, making sure the battery in the laptop doesn't go flat, being worried something's going to get knocked on the floor, blah blah, is a PITA and would also like a bench oscilloscope. Ideally I was thinking about those with battery power options, but I feel these will be out of my price range and I will have to continue to use a USB scope and the laptop when on the road, or inside a moving vehicle.

I now find myself realizing just how poor my grasp of scopes in general is. I need advice on whether I should be looking at analogue or digital bench scopes, what bandwidth I need to look for, and how many channels I really need. I certainly need two, but I have a Thurlby Thandar 20 MHz multiplexer http://www.radiomuseum.org/r/thurlby_os ... lexer.html that might allow me view multiple injector or coil patterns on a single scope input. I have never tried it as I am told you need a scope with a degree of persistence to use it, and I don't think a USB scope would have this? I would also like a colour scope, to make differentiating two or more traces easier, and I also like the USB scope for its ability to show voltage levels and things digitally on screen. I suspect, but don't know, that these criteria will mean I need to look at a digital scope?

The other thing I need advice on is depth of memory. I know Pico go on about how important this is for storing enough data to find an intermittent glitch. It's not something I have used with my Dataman USB scope, but i can see how it would be useful for finding more obtuse issues.

Size and age of machine isn't a real issue now I have decided to consider a bench based instrument. My budget is £600 UK max, so will probably be looking at used stuff. I quite like vintage stuff, so am not necessarily looking for anything on the basis of it "looking modern". I would not want something totally irreparable unless it was dirt cheap though. Can anyone give me some pointers please?

Thanks for reading.
Wally
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by Wally »

Without doubt I consider the Picoscope to be the best option. For £600 you may find a second hand two chanel kit but the only reason you may find one of these is because the owner has traded up to the four chanel kit, which is what I would recommend.

Apart from the technical spec, the one reason I like Pico is because there are so many other users on loads of different forums that you can send recorded log files to and recieve log files from to compare good and bad waveforms.

http://www.autonerdz.com/cgi/yabb2/YaBB.pl

http://www.picoauto.com/support/

Wally
Basil
Posts: 36
Joined: Fri Sep 16, 2011 2:28 pm

Re: Advice re oscilloscope choice for automotive diagnostics

Post by Basil »

Hi, thanks for the reply. Yes, I totally agree, the Pico automotive scope is excellent, but I have already got a far better specced USB scope, all I lack compared to the Pico are the nice menus to pre configure it for various automotive apps. I am really looking for a bench scope, something not reliant on having a laptop as well, or a normal PC. I see what you are saying re looking at recorded log files, but a lot of the stuff I work with is odd ball, and unlikely to be graced with a list of common issues and a load of existent log files out there.

Thanks for the reply, I may well borrow a friend's Pico automotive scope for a play. I have to say the screen shots of them in use show a remarkably clean user interface.
stevieturbo
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by stevieturbo »

Have a nosey at some of the car diagnostic forums. Ilexa, BBA-reman etc as may be more used to using Picosope etc.

Ive never used a Pico, but I have also never read a single bad word about their system. That has to speak volumes for a diagnostic product. The fact it is geared towards automotive use must also be a big plus point. Everything is there ready to go to diagnose car related faults. So that should save time and effort.

Although I do agree using a laptop can be a PITA around a car.

Perhaps one of these new Computer Tablets might be the next big thing for car diagnostic software ?


Certainly a question worth asking on EFI101, or Ive even seen some talk over on Pistonheads about the use of scopes. Although it was ages ago. A couple of guys there did seem to say a bench scope was the ultimate scope. And I'm sure that's true. But best scope, and best scope for a certain application arent always the same thing.

I'd like a handheld or portable one myself. But most seem to be single channel, or very very expensive.
And without logging, not really much use for tracking down intermittent faults.
stevieturbo
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by stevieturbo »

A google finds these portable ones.

http://www.bestoscilloscope.com/handheld-oscilloscope/

Not the most expensive, and if nothing else they look nice lol

http://www.docstoc.com/docs/8993331/POR ... ciLLOscOPE
Jon K
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by Jon K »

I personally use a cheap USB scope -

The model is Hantek 2250. It works well.

Its very useful and has two channels so I have been able to check different sensors/etc against RPM, or cam, or, etc.

Image


Oops - I missed that you want a bench scope. Well, the best is to hit up ebay. There are a bunch of bench scopes (chinese mostly) that are cheap-ish.
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stevieturbo
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by stevieturbo »

When using your scope Jon. Is the display fluid and smooth ? Is there a time delay between a signal appearing and actually creating a signal ( ie cranking or whatever ) ?

I have a cheap USB Stingray scope. 2 channel + signal generator. I dont use it very often, but it just seems very slow to use. ( no doubt hindered by my lack of experience with it )

certainly a friends Snap On Vantage which has a small LCD scope is much faster and easier to use. Although screen is very small and no logging ability and only single channel.

I can see the appeal of a fast easy to use portable unit though, as the Vantage is great even though it is very old.
Jon K
Posts: 602
Joined: Fri Dec 04, 2009 1:45 am
ECU Model: S80 Pro
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Re: Advice re oscilloscope choice for automotive diagnostics

Post by Jon K »

My unit is very responsive but only in certain modes. For instance if I set the cycle time to something semi non standard, it refreshes the screen maybe 2 - 3 frames per second. But, if I pick like 20us, it scrolls smoothly. If I do like 4us or whatever, it might be "laggy". I generally stick to like 1 sec - 10 sec on stuff while cranking, and then like 20ms, 4 ms, etc. But I know there are modes/cycle rates that do lag up for some reason.
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