How many scope channels do you really need?

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5 years 1 month ago - 5 years 1 month ago #27108 by MoleNZ
Hi, I'm a Mitsubishi tech, I'm looking at purchasing a picoscope so I can gain greater knowledge in the diagnostic side of my job.
My work has a Modis Ultra which I use when I can, I even brought my own low amp probe to use with it so I can do fuel pump, ignition coil analysis etc.
Unfortunately diagnosis is a smaller part of my work load, due to the dealerships size (small) and low number of technicians I end up doing a bit of everything, this means my time with the scope is limited and as such my skills using it are also limited.
Anyway I believe if I have my own scope I could use it in my own time and on my own vehicles and become far more proficient with scope diagnosis.
Of course I would like to keep the cost as low as possible, I have done quite a bit of research and decided on a picoscope, but I am undecided on the number of scope channels I really need.
Having looked on other forums it would seem 4 channel is what is most often recommended, but the recommendations don't seem to come with any real world usage to back this up.
So I would like to know from anyone who owns a 2 or 4 channel scope how often you really needed a 3rd or 4th channel (measuring 4 abs sensors at once is not something that would convince me), and if you only had a 2 channel scope what fault did you have that you where unable to solve (or was much more difficult to solve) because of that missing 3rd or 4th channel.
Last edit: 5 years 1 month ago by MoleNZ.

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5 years 1 month ago #27109 by Andy.MacFadyen
The main application that is pushing techs into buying a 4 (or more) channel scope is doing cam-crank synchronization checks on V engines especially those with variable valve timing. As engines are becoming more complex with GDI becoming almost universal a 4 channel scope will become more useful solve those extra complex issues .
You are right about ABS a good scantool will graph wheel speed sensor output and point you to the correct wheel, from which point if more is needed a compact single channel hand held scope such as a uScope would fit the bill.

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5 years 1 month ago #27135 by MoleNZ
True, even on a 4 cylinder with variable valve timing on inlet and exhaust that would be 3 channels used including the crank. I guess it's a case of buying a 2 channel scope and being able to use it for probably the majority of tests but realising some situations will require 3 or 4 channels or spending more for the 4 channel. The price difference is $1000 between the 2 and 4 channel options, I've got more thinking to do.

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5 years 1 month ago - 5 years 1 month ago #27137 by Andy.MacFadyen
You can actually get by with a two channel scope no matter how many postion sensors you want to look at it just takes longer. In the end you have to decide on a comprise. The price of scopes rises exponentially with the speed, channels and number of features they have. Even the cheapest scope will do 95% of the work of the most expensive, a mid-range scope will do 98+%.
Personally I really would love the hardware Frequency measurement feature only on the top end Pico scopes have but no way could I justify one,

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



Last edit: 5 years 1 month ago by Andy.MacFadyen.

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5 years 1 month ago #27163 by Noah
If you have the channels, you'll use them.
Most of the time I get by with two, but when I need the 3rd and 4th, I'm glad to have them.
Like Andy said, cam and crank waveforms on v engines mostly.

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5 years 1 month ago #27360 by GypsyR
I use three channels quite a bit when doing relative compression testing and such.
I bought an outdated original Modis from a pawn shop years ago. Now it's seriously outdated as a code scanner but still great for four channel scope work.

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