Oscilloscope

[PCBONEZ]

Re: Oscilloscope

Looks like a runner.
.
See where it says "Probe Adjust, 500 mV P-P, 1kHz".
That's the port to adjust compensation on the probes I mentioned earlier.
.

[Peter9DO]

Re: Oscilloscope

Yes.
.
Here are the specs for the 'stock' probes for that.

.
Need to get probes with a compensating range that covers the input capacitance.
.
Need to get probes with the correct input resistance.
.
Both the above are different between 1x and 10x probes.
.
You probably want at least one of each of 1x and 10x or one with a 1x-10x switch.
[If you connect to 50v with a 10x probe the scope only sees 5v.]
.
.
When you get the probes connect to the test signal and adjust the compensation for a nice square square-wave on the screen.
[That takes out error due to the cable size and length and the probe.]
The adjuster is usually a very small screw. Location varies.
Could be near the connection to the scope or on the probe itself.
.

By the way, thank you for finding this PDF for me! Here are the images of my purchase.

[retiredcaps]

Re: Oscilloscope

it's in VERY good condition!

From your description in post #36, I'm sure the guy selling takes care of his stuff and probably a little sad to see it go.

[Peter9DO]

Re: Oscilloscope

I got the hard shell cover for the front. The original manuals, the manual holder and it's in VERY good condition! I will post a picture of it here in a little while.

[PCBONEZ]

Re: Oscilloscope

I just snagged a 100Mhz Tek 465M for $70 shipped off eBay.

It's sweet.

I used LOTS of those.
Military version of the 465B.
Very good scope but it's analog.
.
Did you get the hard-shell front cover with it?
.

[tom66]

Re: Oscilloscope

I have two oscilloscopes.

One 100 MHz digital storage scope used for most of my non repair work as it's only 250V maximum input rated and poor single shot capability. (HP 54501A, cost me £150.)

And one 20 MHz analog scope (cost £60), which I have used successfully to repair two plasma TVs; I chose it for 400V inputs and despite what people have said, with care a 20 MHz scope is sufficient for debugging a 720p plasma (and resolved an okay waveform on a 1080p Panasonic) although you are limited in the higher frequency ranges and you have to turn the intensity right up (and lose a bit of focus control). The most common adjustment is the Vsetup and Vsetdn (or Yfr/Yrr) which can be done if you can read 1/5th division.

[Agent24]

Re: Oscilloscope

Now, my question is I need to buy probes, I was looking on eBay, and I was wondering am I able to put 100MHz probes on a 60MHz scope?

Just make sure you get good ones.

There are "100Mhz" probes on eBay from China for like $7... rubbish, don't even bother

Sort of.

I read about that elsewhere before but it wasn't explained as well there.
.
~So~
For analog you want 3x.
For digital [like a square wave] you want 5x.
So a 50MHz scope would only be good for [at most] a 10Mhz square wave.
[And no matter what, more scope bandwidth is better.]
.
Below are some visuals out of the PDF.
A 100 MHz square wave on various bandwidth scopes.

Looks interesting, I think I get it now

[TheLaw]

Re: Oscilloscope

I just snagged a 100Mhz Tek 465M for $70 shipped off eBay.

It's sweet.

[PCBONEZ]

Re: Oscilloscope

Here's the Op manual.

Good luck with the Service manual.
I didn't find that one.
.

[PCBONEZ]

Re: Oscilloscope

I was wondering am I able to put 100MHz
probes on a 60MHz scope?

Yes.
.
Here are the specs for the 'stock' probes for that.

.
Need to get probes with a compensating range that covers the input capacitance.
.
Need to get probes with the correct input resistance.
.
Both the above are different between 1x and 10x probes.
.
You probably want at least one of each of 1x and 10x or one with a 1x-10x switch.
[If you connect to 50v with a 10x probe the scope only sees 5v.]
.
.
When you get the probes connect to the test signal and adjust the compensation for a nice square square-wave on the screen.
[That takes out error due to the cable size and length and the probe.]
The adjuster is usually a very small screw. Location varies.
Could be near the connection to the scope or on the probe itself.
.

[Peter9DO]

Re: Oscilloscope

So I bought the Tektronix 2220 O-scope today!!!!! 60Mhz, 2 Chan, with digital storage.

First of all I was so impressed at this guys set up! It was unbelievable! 4 work stations with scopes, soldering and DESOLDERING stations, hot air, power supplies and everything else you would want at each station! Need I say this is all in his basement. Not gonna lie, My jaw hit the ground, especially when I saw Hakko desoldering stations at each station, that's got to run close to $600 each..... wow!

Anyways, he gave me a crash course on how to use it, he had a 100MHz and this 60MHz he said that he really thinks that the 100MHz would be overkill for what I'm trying to use it for. That the 60MHz would do just fine. I bought the unit with no probes for $200.

Now, my question is I need to buy probes, I was looking on eBay, and I was wondering am I able to put 100MHz probes on a 60MHz scope?

[PCBONEZ]

Re: Oscilloscope

Yea, these issues don't come up that frequently for me, but again I think it would be nice to have it on the bench if I need it, at least it's there you know what I mean!

Now to the extent of your conversation about the 3x grater I will keep my eye out for any deals I may find that are a little better. I'm really not in a rush to buy one and I would like to hold off to get one that is right for me at the price I can afford. As you have mentioned I will need to buy a function generator as well (or build one). This is going to get expensive, I can feel it!

Thanks again guys for all the help with this stuff! I will be asking for lessons next! lol!!!!! No, I'm kidding but I'm sure I will have some questions on how to use it from time to time.

I think if you hold out for a good deal you can score 100MHz used scope in your price range without too much problem.
-
O'scopes have a test signal point built into them [it's usually a 1v 1kHz square wave provided to adjust the probes] so if some ad doesn't show an actual signal [vice a flat line] then don't assume the scope works. A scope can show a flat line without processing any input signals at all.
Alternately if the ad says it passes it's self-check [which some scopes have built in] then it's probably okay.
.
You want the -SERVICE- manual for it. Make sure you can get one.
That will tell you how to adjust and calibrate it yourself - although for some things you'll need additional equipment or parts.
.
I went with Tektronix partly because they made zillions so parts are still available.
There are definitely other good brands.
I just dunno much about parts support for those brands I don't have.
.

[Peter9DO]

Re: Oscilloscope

A Tektronix 2220 would do fine as a first scope if it 'runs'.

So far as how frequently you will need the scope, probably not as often as you think.
There -ARE- some things you can't check without one but they don't come up every day.

For instance, as you do laptops, how much ripple is that power brick sending out?
Being able to check can save you a lot of time and avoid replacing good power bricks just because you aren't sure about the old one, ,
, but how often does that come up for you?
I can't know that.
I'd say if it saves you from tearing apart or replacing something like 10 power bricks [that didn't need fixed] it will have paid for itself.
.
Same thing with PC and screen power supplies.
You don't -really- know if they are good without checking the ripple.
.
.
Yes for signal tracing you would need a signal generator of some kind.
It doesn't have to be fancy though and there are actually schematics for DIY basic ones online.
One that simply output a square wave at various frequencies would be good enough for most things.
Can't see that coming up too much though.
.

Yea, these issues don't come up that frequently for me, but again I think it would be nice to have it on the bench if I need it, at least it's there you know what I mean!

Now to the extent of your conversation about the 3x grater I will keep my eye out for any deals I may find that are a little better. I'm really not in a rush to buy one and I would like to hold off to get one that is right for me at the price I can afford. As you have mentioned I will need to buy a function generator as well (or build one). This is going to get expensive, I can feel it!

Thanks again guys for all the help with this stuff! I will be asking for lessons next! lol!!!!! No, I'm kidding but I'm sure I will have some questions on how to use it from time to time.

[PCBONEZ]

Re: Oscilloscope

The rated bandwidth of an oscilloscope is the SINEWAVE bandwidth. A pure sinewave has no harmonics. If you're trying to measure a switching signal which is usually a square wave, you need to be able to accurately measure at least the 3rd harmonic as well (tho catching up to the 5th is preferable), so you need your scope to have at least 3x the bandwidth of the signal you are measuring.

Sort of.

I read about that elsewhere before but it wasn't explained as well there.
.
~So~
For analog you want 3x.
For digital [like a square wave] you want 5x.
So a 50MHz scope would only be good for [at most] a 10Mhz square wave.
[And no matter what, more scope bandwidth is better.]
.
Below are some visuals out of the PDF.
A 100 MHz square wave on various bandwidth scopes.
.
.
100 MHz square wave on a 100 MHz scope. [1x]


.
.
100 MHz square wave on a 500 MHz scope. [5x]

.
.
100 MHz square wave on a 1 GHz scope. [10x]

.
.
100 MHz square wave on a 2 GHz scope. [20x]

[Th3_uN1Qu3]

Re: Oscilloscope

I don't understand why they do it that way myself.
The 50MHz is the bandwidth of the 'guts' of the scope. [Not what you are measuring.]
The 3x thing has something to do with avoiding errors due to harmonics.
16MHz could have harmonics at 32 and 48 MHz so 3x only covers the first two [the most likely] higher harmonics.

The rated bandwidth of an oscilloscope is the SINEWAVE bandwidth. A pure sinewave has no harmonics. If you're trying to measure a switching signal which is usually a square wave, you need to be able to accurately measure at least the 3rd harmonic as well (tho catching up to the 5th is preferable), so you need your scope to have at least 3x the bandwidth of the signal you are measuring.

[PCBONEZ]

Re: Oscilloscope

I don't understand why they do it that way myself.
The 50MHz is the bandwidth of the 'guts' of the scope. [Not what you are measuring.]
The 3x thing has something to do with avoiding errors due to harmonics.
16MHz could have harmonics at 32 and 48 MHz so 3x only covers the first two [the most likely] higher harmonics.
Could also have harmonics at 8MHz and 4 MHz on the lower side.
- So lets say you are measuring 48Mhz with a 50 MHz scope.
- If you don't have the 3x margin how do you know you aren't actually looking at a low harmonic of 96MHz in the circuit?
.
That might not make any sense, I just woke up...
.
About the time the theory gets that deep I go goo goo eyed and push the 'I believe' button because I'm getting bored with it.
I'm not out to design a scope.
All I wanna know is what I need to measure what I want and 3x is what 'they say'.
.

[Agent24]

Re: Oscilloscope

Sorry, I didn't see that before.
The MHz is the Bandwidth.
The scope's bandwidth should be at least three times the bandwidth of the signal to be measured.
In other words a 50MHz scope is good for measured frequencies less than about 16 MHz.

This is something I have not yet understood. Why can't a 50Mhz scope display a 50Mhz waveform? Or can it?

If it can only measure 16Mhz signals well, why is it not called a 16Mhz scope?

Is it all just down to marketing?

[PCBONEZ]

Re: Oscilloscope

A Tektronix 2220 would do fine as a first scope if it 'runs'.

So far as how frequently you will need the scope, probably not as often as you think.
There -ARE- some things you can't check without one but they don't come up every day.

For instance, as you do laptops, how much ripple is that power brick sending out?
Being able to check can save you a lot of time and avoid replacing good power bricks just because you aren't sure about the old one, ,
, but how often does that come up for you?
I can't know that.
I'd say if it saves you from tearing apart or replacing something like 10 power bricks [that didn't need fixed] it will have paid for itself.
.
Same thing with PC and screen power supplies.
You don't -really- know if they are good without checking the ripple.
.
.
Yes for signal tracing you would need a signal generator of some kind.
It doesn't have to be fancy though and there are actually schematics for DIY basic ones online.
One that simply output a square wave at various frequencies would be good enough for most things.
Can't see that coming up too much though.
.

[Peter9DO]

Re: Oscilloscope

I would assume you are talking about ones like this?
http://www.seeedstudio.com/depot/mic...ano-p-512.html

They generally top out at about 1Mhz, so pretty useless.

Precisely!

[Agent24]

Re: Oscilloscope

Oh..... Yea, see if you put DSO scope in you will see the items I'm talking about. It almost looks like the back of a camera. A small portable oscilloscope, with maybe a 3" screen. It looks very cheap and I thought that's what you were talking about.

I would assume you are talking about ones like this?
http://www.seeedstudio.com/depot/mic...ano-p-512.html

They generally top out at about 1Mhz, so pretty useless.