From: John B <dylanb_at_sympatico.ca>
Date: Tue Nov 23 19:19:13 1999

-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
Date: Tuesday, November 23, 1999 9:06 PM
Subject: Re: Oscilloscopes

>> It's rare that I do. Used to have a 465B, didn't use it enough to
>> maintaining it or it's weight. While the book calls for a better scope,
>> I know the 20mhz B&K would be more than enough to track 8F core problems
>Sure... But if you're buying a 'scope, it makes sense to get one that
>will do all that you might need. So while you don't need a 50MHz 'scope
>or whatever to sort out 8/f core memory, you might find it worth getting
>one for other work.
>> as I used it to set the slice time. Then again, I know how to get the
>> out of a scope too.
>Oh sure...
>There are some people here (you're certainly one, I like to think I'm
>another) who (most of the time, at least :-)) understand what we're
>trying to look at and understand just what our test gear will do when
>given a strange signal. We know what our '20MHz' scope will do with a
>30MHz signal. And we know how to push the instruments a bit.
>You don't _need_ expensive test equipment. I've done a lot of fault
>tracing using a cheap analogue multimeter and a Radio Shack logic probe.
>And with those 2 instruments I managed to extract enough clues to the
>fault to replace the fault component first time (most of the time).
>However, I am also sure that there are people here who could use some
>more clues as to the fault, who can't interpret every last piece of
>information that they can get from simple instruments. And those people
>generally make use of rather more instruments, which perhaps aren't
>strictly necessary...
>Don't get me wrong -- there are times when _I_ find a 'scope essential.
>Perhaps if I was more clueful I'd not need one then either, but I do. But
>I've also discovered that _very_ rarely do you need a new and expensive
>piece of test gear to fix a classic computer. Most likely you can do it
>with what you already have if you think about the problem.

I agree but I would not recommend someone dropping a couple hundred bucks to
fix an old 20Mhz scope as I am sure they would not limit their use
*exclusively* to vintage minis. A 20Mhz scope in RF/High speed logic
troubleshooting/design is totally useless. A 20Mhz scope isn't even very
good at looking at the color burst of a video signal in any detail. Again, I
find most folks design/troubleshoot in a variety of areas and that's why we
need scopes with all the toys. I don't see Tek making any more 20Mhz boxes.

>I was discussing a related subject with a friend earlier this evening. We
>came to the conclusion that experienced hackers (this was actually about
>mechanical engineering, but it applies to electronics as well) can do a
>lot of good work using 'scrap' components and a few tools/instruments.
>But beginners probably should use new (and known-good) components and
>have rather more instruments. Of course it's often the other way round --
>beginners don't have the money to spend on a hobby they may not continue
>with, while experienced people have obtained a good collection of tools
>and test gear over the years (and really know how to use it!).
Received on Tue Nov 23 1999 - 19:19:13 GMT

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