100hmz vs 200mhz oscilloscope

[kalilinux25]

Hi I was planning to buy a oscilloscope for laptop board repair do i really need to buy a 200mhz ? or the 100mhz is enough?

[stj]

Re: 100hmz vs 200mhz oscilloscope

100Mhz scopes will show a waveform well over 200Mhz, it is just the limit where the readings start to lose accuracy.
i have seen a Rigol 100Mhz scope display a 350Mhz sinewave before!!

[kalilinux25]

Re: 100hmz vs 200mhz oscilloscope

So your saying that for laptop baoard repair 100mhz will do?

[stj]

Re: 100hmz vs 200mhz oscilloscope

no, i dont repair laptops - for all i know you may need 500Mhz
all i'm saying is a 100Mhz scope will still show 200Mhz waveforms

[Curious.George]

Re: 100hmz vs 200mhz oscilloscope

Hi I was planning to buy a oscilloscope for laptop board repair do i really need to buy a 200mhz ? or the 100mhz is enough?

That depends on what sorts of problems you expect to be capable of diagnosing.

A power supply can probably be diagnosed with a 10 MHz 'scope. If you want to look at waveforms to/from a bank of DDR3, you'll likely be able to see "activity" with a slow 'scope but won't be able to verify Vhi and Vlo (as well as timing relationships between signals).

But, chances are, you wouldn't be able to recognize if something was subtly wrong (IME, most problems manifest "spectacularly").

The bandwidth of the 'scope essentially tells you what sort of an "RC" filter the 'scope represents. As frequencies of observed signals exceed the 'scope's bandwidth, they will be attenuated by this "filter" (as viewed by the 'scope). The more you (think you) need to see those fine details, the more bandwidth you want/need.

[Often, you can troubleshoot a product with a voltmeter and a logic probe]

[CapLeaker]

Re: 100hmz vs 200mhz oscilloscope

i've only got a 100mhz o'scope and its all i ever needed

[Curious.George]

Re: 100hmz vs 200mhz oscilloscope

i've only got a 100mhz o'scope and its all i ever needed

Yup. I have a couple of 2G/s DSOs (500MHz b/w) but only use them to document waveforms (as a DSO, I can retrieve the contents of the waveform memory).

For more than 4 signals, I drag out a LA for the same goal.

Things tend to work -- or not.

OTOH, when you're designing stuff, you want to be able to verify that everything you think SHOULD be happening is actually, in fact, happening. E.g., monitoring the configuration values jammed into the SDRAM to ensure it's operating with the correct refresh interval, bus timing, etc.

[LA is a real win, there!]