Products > Test Equipment
Choosing an oscilloscope
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0culus:
CROs, due to the exact relationship between the crt trace and the input, have a level of tactile-ness that DSOs can't match. This is really important for a beginner. Running a modern scope is a LOT easier if you know how to run a CRO. Well, cussing the damn thing because of the menus aside. I &%#$ing hate menus. This is part of the reason I choose to use old scopes and spectrum analyzers in my personal lab.
george.b:

--- Quote from: SilverSolder on October 12, 2020, 10:43:32 pm ---Finding a shorted tant using a toner, milliohmmeter, or other current tracking tool isn't that hard?  And they don't blow as often as their reputation would have you believe...  I have seen exactly one blown tantalum cap in my entire pile of old tech, and it was the reason for that particular instrument going cheap on eBay as a non-working unit.  It just isn't something I'd worry about.

--- End quote ---

Not so in my experience. I've seen lots of failed tantalum caps, exploding or not, in equipment old and (relatively) new.
Besides, I don't imagine too many beginners who are looking for their first scope have a milliohmmeter. Failed tantalum capacitors was just an example that occurred to me anyways; older scopes can have a complex construction, with many more parts to fail, and without proper tools, chasing down a failed component can be frustrating, especially to a beginner, and especially when you'd rather be using the equipment for actually getting some work done.


--- Quote ---Absolutely you can get in trouble finding parts for an older piece of equipment.  But typically, the things that fail in older equipment is not the fancy unobtanium stuff, instead it is the usual drying capacitors, failed power transistors, hot resistors drifting out of spec, bad solder joints, etc.  -  It can get a bit tricky to find exact matches for old semiconductors, but usually there is an acceptable modern substitute.

--- End quote ---

Again, not necessarily so in my experience. My 2430A had a bad ASIC, in addition to a tantalum cap that had failed enough to drop the rail it was on, but not enough to either explode or trip the overcurrent protection. Another scope I got had a blown HV transformer, which has proven impossible to find a replacement for. Granted, my PM3055 had bad caps and a blown light bulb, that was pretty much it. Other than the disintegrating case plastics, that is. Or the blown RIFA cap, but that's a given. Ah, and a failed power switch. ;D


--- Quote ---Worst case, you buy another one on eBay and use for spare parts.

--- End quote ---

Assuming you've been graced with living in a place where that's an option, yes? Not all of us have been bestowed such grace. ;)

In contrast, repairing three TDS200 series scopes - each with a different set of failures - was by no means the impossible task one'd imagine it would be for a comparatively modern scope, lack of schematics notwithstanding. And believe me, they were in a sorry shape.

I agree with what has been said about some scope being better than no scope. My first scope was the PM3055 I mentioned, and that was a far sight better than no scope. However, cost should definitely be weighed in. As I said on my first reply on this thread, if sufficiently cheap, then sure, an analog scope can be a good option. For a beginner in my country, for instance, it can be pretty much the only viable option - a Rigol ds1054z can be had brand new for the equivalent to $700 here, and the secondhand market isn't much help. :--
rsjsouza:

--- Quote from: tggzzz on October 12, 2020, 08:25:59 pm ---
--- Quote from: Golds on October 12, 2020, 07:19:05 am ---It is not recommended that you choose an oscilloscope that is too old, because you cannot predict that it will suddenly malfunction

--- End quote ---

Or, to put it another way, which is worse: something working which might break and need to be repaired, or something buggy that cannot be made to work to specification?

--- End quote ---
Well, to be fair anything can break, thus the scale tends to move towards the old analog unless you are talking about a new equipment with warranty. If that is the case, the modern entry level (even the ultra bottom of the barrel such as a Hantek or Uni-T) can show a waveform on a screen, despite not meeting specs (or having very poor ones).


--- Quote from: 2N3055 on October 12, 2020, 10:35:23 pm ---You cannot have 40 year old analog scope as your first and only scope as a beginner.
(...)
. If you can get working one for free or very little money, by all means, take it. But don't pay money for it that would buy you new Rigol or Siglent...

--- End quote ---
I wouldn't go as far to say "you cannot have", but instead as you correctly point later in your post: if you can get one for cheap, by all means do it. It is better than "no scope". And it does not even need to be analog, but a used Rigol DS1052E or DS1102E for US$100 (or US$150 if in really good shape) is already a great starter (prices for the US used market, as I know other countries may have higher prices for used gear).
Fungus:

--- Quote from: Martin72 on October 12, 2020, 11:00:52 pm ---
--- Quote from: Fungus on October 12, 2020, 05:59:31 am ---It's definitely better than the Rigol now that Instek has added all the serial decoders and other features to it.
--- End quote ---

Which are ?

--- End quote ---

All the ones it didn't have before.
Fungus:

--- Quote from: george.b on October 12, 2020, 07:06:41 pm ---
--- Quote from: SilverSolder on October 12, 2020, 02:35:51 pm ---
--- Quote from: Golds on October 12, 2020, 07:19:05 am ---It is not recommended that you choose an oscilloscope that is too old, because you cannot predict that it will suddenly malfunction

--- End quote ---

There is some truth to that - but many hobbyists and professionals use high quality equipment from the 60s - 00s that is still alive because it is repairable.

--- End quote ---

I find this often-repeated fact of greater repairability with older gear to be, while not untrue, overstated, and therefore potentially misleading.

--- End quote ---

Yep. Having the schematic available doesn't magically make things repairable.
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