About to buy Tektronix 475.First oscilloscope so need price advice!

[Brumby]

Realise the seller is working in good faith and hoping his trip will not be in vain.

If he is willing to bring the scope to you - and a function generator - then I feel there is a distinct possibility he might be happy to give you a quick run-down on operation of the scope - partly so he can 'sell' it as a fully working unit and partly to share an interest that you are showing.

It all sounds promising.  Let us know how it goes.

[David Hess]

I was considering a 465/475 mainly because these are supposed to be more serviceable than the other Tek scopes.

I think the 465/475/465B have more custom parts than the 2235 but I would not consider that a factor to chose between them because the custom parts are pretty reliable.  You have to go back to the 453/454 for something that uses all standard parts and then you will have to deal with a smaller CRT.

Servicing can be tricky on the 465/475 and 2235 just because of physical access.  The 465M is *another* not 465 like the 465B with a very different physical design which may be easier to service although they look the same on the outside.  Still, I would not wait for any of these once one at a reasonable price became available.

For what it is worth here are the rough groups these oscilloscopes can be divided into.  They all have dual delayed sweep:

453 - 50 MHz Discrete
453A - 60 MHz Discrete
454 - 150 MHz Discrete
454A - 150 MHz Discrete

455 - 50 MHz Mixed Sweep High Reliability
465M - 100 MHz Mixed Sweep Military

465B - 100 MHz Alternate Sweep
468 - 100 MHz Alternate Sweep Digital Storage

These all have mixed sweep:
464 - 100 MHz Slow Analog Storage
465 - 100 MHz
466 - 100 MHz Fast Analog Storage
475 - 200 MHz
475A - 250 MHz
485 - 350 MHz

The 2-channel 22xx oscilloscopes have several series as well but I am not going to list them other than to say that the 2235 and mentioned 2230 are in the same series.

If you choose Tektronix, I recomand the 465B or the 2235.

The 465 does not have any advantages over a 475 - and the 475 has a higher bandwidth, which is important for some purposes.

The 465 is *not* a 465B (or 465M); they can be consider separate models with the 465B replacing the 465.

The 465B and 2235 support alternate sweep instead of mixed sweep on the 475.  I have never found a good use for mixed sweep but apparently it is handy for working with analog video.  Alternate sweep on the other hand is generally useful.  If you have not used alternate and mixed sweep, then I doubt you will miss either.

[ez24]

Asked the seller to bring a function gen with the scope in order to roughly check both channels before I buy it.

Hope you do not lose it by dicking around with these responses and pressuring the seller.  The scope has a built-in calibrator that you can hook the probes to.  If you can see the signals and the switches are not dirty - buy it.  Because you can see it before you buy, with ebay you cannot.  I bought and lost out on two analog scopes on advice from this forum (they were both bad).

Keep reading everyone's answers and you will lose it.

[belzrebuth]

@ez24

The price is definitely higher than normal so why not daunt the seller a bit ?

I agree that the generator is not a necessity but since the seller mentioned he sells one I told him he could bring it along and he agreed.

I could end up buying that too although I doubt it if the price is similarly raised,keeping in mind for how much the cheap dds gens are going for on ebay.

I don't quite follow you on the forum advice though.
In my case I think it's been pretty clear from my posts that I was probably going to go for it but needed some advice on whether this is a really bad deal or an acceptable one.
I know it's working but I wasn't so sure it's a solid choice given its raised price.
Nobody tried to "convince" me to buy it or not even though nice points have been made for both.

You mean that you bought two analog scopes based on advice from this forum and both turned up bad?
I don't see how that relates with your final sentence about  me "losing it".
From your experience I'd expect to tell me to check as much as I can and be really cautious when doing so ,so I won't get a lemon;not being cautious not to pressure the seller.
My english is not perfect but I think that you slightly contradict yourself.

What would you do in this situation?

[tautech]

It's rarely a mistake to buy one of these IF you have the ability to repair it something goes wrong.
If it's a well loved CRO and possibly had some preventative maintenance done on it due to its age It could well be fair value for the money.
I've owned a number of CRO's, all of which needed some repair and that gave me a reasonable understanding of their weak points. General recommendation up until recently was to get a CRO as your first scope but affordability was the primary reasoning driving such advice.
Those that have learnt scope usage with a CRO are better prepared for future DSO ownership but in saying that a DSO is much more capable but more complex to use to its full potential. For the real novice a DSO is easier to learn with.
Reliability is king for the novice, you'd be better to get something new and pursue your hobby without the interruption of a broken scope. 

The forum is full of threads of newbies with broken CRO's and while we're all willing to help there's not much that can be done as many don't have the understanding or tools to go about many of the more complex or HV repairs.
If you think you know what you might be letting yourself in for, go for it and good luck.

[EEVblog]

OTOH, I bought a Rigol DS1054Z a couple of months ago and it is now my go-to scope.  I wanted 4 channels with serial decoding and I was willing to give up bandwidth to get them.  The single-shot feature alone is worth buying digital over analog.

And that's the trick, without single shot capture available on a digital scope you are missing out on a whole world of signal capture that is invaluable for learning and desiging electronics with.
This isn't about paying more for better bandwidth, more memory etc, it's about a huge fundamental difference in tool capability.

[tggzzz]

If you get a working scope at a price that is acceptable to you, then stop agonising over your decision! Buy it, enjoy using it, learn from it, and then - if your interests/needs change - you will be in a good position to know why the current equipment is no longer adequate, what you need next and why.

IMNSHO, seeing a secondhand scope working is a definite advantage, and is worth money to you. Doubly so if they teach you how to use it! Analogy: it is worth paying extra in a high street shop to see and try on clothing, or listen to the sound quality of a television.

It doesn't do any harm to ask them why they are selling it, and whether they know of any problems with it.

Unless you need to be able to capture transients, a working 475 is a good scope - especially for signal integrity problems. The few times I've needed to capture transients (PSU startup problems) I've been able to use a very cheap storage scope since the bandwidths are very low.

[Brumby]

If you get a working scope at a price that is acceptable to you, then stop agonising over your decision! Buy it, enjoy using it, learn from it, and then - if your interests/needs change - you will be in a good position to know why the current equipment is no longer adequate, what you need next and why.

Very much this ^^^^^.

While there may be some who cringe at the idea of getting a scope that doesn't feature 'X' or function 'Y', you will learn - and any scope is better than none.

From the general feel of the comments given in regards to the 475 that you will be looking at soon, if it is shown to be working, you have a big advantage in the transaction over people purchasing by a photo on the internet.  By having personal contact with the seller, you may be able to find out a little about the history of the unit, how well it's been cared for - and, as I said, perhaps have the seller offer you some useful tips on using the scope.

There will always be a better scope.  Start somewhere.

[belzrebuth]

Bad news guys!

The seller got it here but he didn't come up home just unloaded it from his car ,took the money and left!

So I'm stuck here with a scope I know that only turns on.
It's not in good shape btw..

I really think I'm in big trouble here..

Can anyone help me confirm the scope is actually ok?
I can post pictures if needed

[tggzzz]

Bad news guys!

The seller got it here but he didn't come up home just unloaded it from his car ,took the money and left!

Oh dear. There's a generic lesson there - have the money inside and get them to demo it before locating the cash And be prepared to abort if something unexpected occurs.

So I'm stuck here with a scope I know that only turns on.
It's not in good shape btw..

I really think I'm in big trouble here..

Can anyone help me confirm the scope is actually ok?
I can post pictures if needed

What do you mean by "not good shape" and "turns on"? Do you see any lights? Can you see anything on the CRT? Centre the time, y position, trigger level controls, auto triggering. Turn up the intensity and press "beam find".

There are "how to use a scope" instructions on the web, e.g http://www.doctronics.co.uk/scope.htm

[newbrain]

The seller got it here but he didn't come up home just unloaded it from his car ,took the money and left!

Ouch, this does not bode too well, after he promised to even bring a FG...

Here you can find  the manual:
http://w140.com/tekwiki/wiki/475

Let's start from the basics:

• You said it turns on, can I assume you actually tried?
• Check that the voltage selector on the back is set to the right voltage, even if it turns on.
• Set the time base to a reasonable value (500µs), the trigger mode to AUTO and  the input coupling selectors to GND
• Also, set the Intensity pot to an high value and the vertical mode to ALT
• Can you see a trace (two actually)?
  If yes:
  Good there will be more tests, but this a start.
  If not:
  Press the BEAM FINDER button, if a trace is displayed, use the Position pots (V and H) to bring it on the screen after releasing the Beam finder.
  Use the Intensity and Focus pots to have a clear trace of reasonable brightness.
  If still nothing:
  That's bad. Something is not working.
  
• With a trace on the screen, select an appropriate vertical V/div (100mV), put the coupling selector to DC, and connect one channel to the calibrator:
  you should see a square wave about 3 divisions high and with a 1 division half-period.

If the above goes well, congratulation: you have a working scope (not 100% certain, but very good chances).

[belzrebuth]

First thing I noticed is that I have to mess a lot with the slope level to get a signal.

Here's what I did so far:

I connected one probe set to 10x to the calibrator and compensated it in order for the square to be straight.

Channel 1 settings are:
10mV per DIV
AC coupled

CH1 button pressed
Horizontal display: A lock knobs button pressed.
Trig mode : AUTO

The square I get from the calibrator looks squashed at the right end.
Controls are crusty ;almost intermittent.

And I get this :

[belzrebuth]

The TIME/DIV knob I'm not so sure it actually aligns with its plastic backside I placed it ten clicks after its left end marked X-Y at .2ms

[newbrain]

The TIME/DIV knob I'm not so sure it actually aligns with its plastic backside I placed it ten clicks after its left end marked X-Y at .2ms

The UNCAL indicator is lighted in your picture. Turn the red "VAR" Time/DIV knob fully clockwise till the "click".

[belzrebuth]

No matter how I turn the VAR knob the UNCAL light does not turn off.

[newbrain]

No matter how I turn the VAR knob the UNCAL light does not turn off.

The manual says:

VAR:
Provides continuously variable (uncalibrated) sweep rates between the calibrated settings of the TIME/DIV switch. Varies the A Time Base sweep rate in the non-delayed mode of horizontal operation and the B Time Base sweep rate in the delayed sweep mode. Extends the slowest sweep rate to at least 1.25 seconds/division. Sweep rate is calibrated when the control is rotated fully clockwise to the calibrated detent.

Does the Timebase change when rotating VAR?

[ez24]

No matter how I turn the VAR knob the UNCAL light does not turn off.

Does it click?  Maybe just a slight force will make it click?  There is a slight resistance there.

[belzrebuth]

It doesn't turn a full circle like the VAR knob on the VOLTS/DIV it does just clicks from one point to the other.
It clicks in place but I don't see much difference.

I'm starting to think that I have to call back the seller
.
I'm really a noob but I don't think that's a fully working scope.

Can anyone tell me what I need to do to confirm that the scope is fine or not?
Knob settings maybe?
I can take photos of the scope with the recommended settings so we can verify what the scope shows accordingly.

[ez24]

After you return it, you really need to buy a new one.  I do not think an used scope will fit your needs.

[belzrebuth]

I think I agree on the new one.
But I'd really like to test it before returning if possible.

I may be a complete fool right now and the scope could be fine.

We can never know if we don't verify that the scope is faulty.

[ez24]

I may be a complete fool right now and the scope could be fine.

Since I know Tek and not you - I agree with both

You do have the manual?  Go through the Basic Oscilloscope Displays section

[tggzzz]

First thing I noticed is that I have to mess a lot with the slope level to get a signal.

Here's what I did so far:

I connected one probe set to 10x to the calibrator and compensated it in order for the square to be straight.

Channel 1 settings are:
10mV per DIV
AC coupled

CH1 button pressed
Horizontal display: A lock knobs button pressed.
Trig mode : AUTO

The square I get from the calibrator looks squashed at the right end.
Controls are crusty ;almost intermittent.

And I get this :

Clearly the scope is not completely faulty.

I suggest you take a deep breath, turn the scope off, find the scope's manual, and read the "operating information" section to find what controls are where[1].

In it you will find a subsection "obtaining basic displays". Connect a probe to the cal input, and follow the examples in the "obtaining basic displays" section.

[1] Note that modern DSOs are typically worse at this point, since many controls are invisible and are hidden in a menu structure. OTOH, they often have a "display something" button!

[belzrebuth]

I think the VAR knob in the TIME/DIV knob is permanently pushed down (broken in probably).
I cannot see the screw on the red knob whereas I can see the screws of the other VAR knobs on VOLTS/DIV.
I can't also turn the var knob a full circle.

[tggzzz]

I think the VAR knob in the TIME/DIV knob is permanently pushed down (broken in probably).
I cannot see the screw on the red knob whereas I can see the screws of the other VAR knobs on VOLTS/DIV.
I can't also turn the var knob a full circle.

You should be able to see the grub screw.

Including clicking into the calibrated position, it should rotate just over 270 degrees (not 360 degrees).

[belzrebuth]

I think I'll try to find the seller and convince him to take it back..