Beginner Looking to Buy Analog Scope on Ebay

[AutogolazzoJr]

I found a ~100 dollar tektronix 1102 'scope on ebay. Looks good cosmetically, but they are selling as is. They tested the functionalities and says it seems as if everything is working, and showed a trace on the screen. The question I'm asking is- should I buy it? I found a site that sells service manuals -  the only problems i could think of it having is dirty controls, faulty triggering, or broken saving. Is that stuff easy to repair, and should I take the chance?

[edavid]

1102 is not the right model number...

[Fungus]

should I take the chance?

Only if you have another oscilloscope to diagnose this one.

[tggzzz]

Simple question: if the scope trace doesn't match what you expect, how will you determine whether the fault is in the scope, the circuit or the oscilloscope? Answer: you can't!
EDIT: ... in your understanding, the circuit...

You use a scope to find faults in your circuit or your understanding.

For beginners, scopes are often overkill - with imagination and understanding you can do a hell of a lot without one. Consider joining a local hackspace or radio amateur society, and use their equipment to determine what you need  and why.

[nctnico]

Simple question: if the scope trace doesn't match what you expect, how will you determine whether the fault is in the scope, the circuit or the oscilloscope? Answer: you can't!

You can if you have a function generator. The signal on the screen should match the settings on the function generator. BTW 1kHz is a very nice frequency for test signals because it is high enough to get a nice trace but low enough to forget about frequency depedant behaviour. Still I'd save up more money and get a new DSO instead of a piece of antique.

[tggzzz]

Simple question: if the scope trace doesn't match what you expect, how will you determine whether the fault is in the scope, the circuit or the oscilloscope? Answer: you can't!

You can if you have a function generator. The signal on the screen should match the settings on the function generator. BTW 1kHz is a very nice frequency for test signals because it is high enough to get a nice trace but low enough to forget about frequency depedant behaviour. Still I'd save up more money and get a new DSO instead of a piece of antique.

Known good equipment helps reduce ambiguities, but subtly faulty scopes, probing techniques etc remain to catch unwary - and sometimes the wary!

For a beginner, a working scope is the priority - analogue or digitising is a second-order consideration, since both are useful.

If someone can get the educational discount, the Digilent Analog discovery should be considered very seriously.

(BTQ, I edited my message to be a little less repetitive )

[Fungus]

Simple question: if the scope trace doesn't match what you expect, how will you determine whether the fault is in the scope, the circuit or the oscilloscope?

You forgot:
a) The probe
b) The probing technique

If you have another probe then (a) isn't much of a problem (assuming you actually try another one). B) is more tricky.

[tggzzz]

Simple question: if the scope trace doesn't match what you expect, how will you determine whether the fault is in the scope, the circuit or the oscilloscope?

You forgot:
a) The probe
b) The probing technique

If you have another probe then (a) isn't much of a problem (assuming you actually try another one). B) is more tricky.

See the previous reply, #6