Oscilloscope recommendation for automotive diagnostics please?

[Chris Wilson]

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 have been using a Dataman USB scope http://www.dataman.com/oscilloscopes/dataman-526-150-mhz-usb-oscilloscope.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 asking about those with battery power options, but I think 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_oscilloscope_multiplexer.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?

 

Another 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 though, unless it was dirt cheap. Can anyone give me some pointers please, particularly re analogue V digital and on screen voltage level displays?

 

Thanks for reading.

[Shane]

As a business why not consider hiring one? Livingstone have been around for years and have a good reputation. Had a quick look and this would fit the bill: http://www.livingston.co.uk/p_yokogawa/general-purpose/oscilloscopes/yokogawa-dlm2024/

 

I know a guy in MK who wheels and deals in test gear, I am back in work on Tuesday and will give him a call and in the meantime send him the text from your post.