[murphy625]

I've been looking around for an old used scope for servo diagnostics.

Can someone make a suggestion on what I'll need?

Dual trace?

What maximum bandwidth?

Thanks, I hope I posted the right topic in the right forum this time

[Al_The_Man]

You will find lots of tektronix on ebay, the older crt 'scopes are heavy to lug around, but you can pick them up cheap and they are one of the best, and will have a bandwidth that will be plenty for most servo applications.
Of course if you just need to diagnose and tune the servo's, most of the Motion card makers include a on screen 'scope for PID tuning.
Al

[murphy625]

Of course if you just need to diagnose and tune the servo's, most of the Motion card makers include a on screen 'scope for PID tuning.
Al

Al,
Can you please elaborate on where I can find this software or utility for my Galil 1832 card.?? My purposes are for servo tuning only. After replacing

By the way, your suggestion in another thread about using native galil commands to diagnose the problem paid off big time.
It let me write a timer file that showed the incoming pulses in a variable and this lead me to the problem.
Thanks again...

[Al_The_Man]

It is one of the Galil downloads that you have to pay for unfortunately (WSDK32), But it has auto tuning, where it runs the servo in a series of tests and plugs in the suitable parameters, and displays the results in a multichannel 'scope format.
There is a video on the Galil site of Dr J. Tal using it to tune a servo.
On the subject of native commands, one to implement when programming the e-stop routine is when the system is in a e-stop condition it is usuall to disable the drives, what can happen is that if the servo is moved by hand or a z axis backfeeds, when the power is restored the servo can jump severely because it sees this movement as an error, if a SH (servo here) command is issued in a constant loop, when power is restored the servo will not move.
Al

[murphy625]

This thing has cost enough money already.
I have to cool it for a while.

Thanks for the suggestions!!!
You r the man AL

[ViperTX]

Tektronic 435 or 465, dual trace 10:1 probes....I've forgotten the Tek Numbers.

[murphy625]

I dont suppose anyone has a "trial" copy of that WSDK32 program??
How much does it cost?

I'll have to compare this to the going rate for a low end O-scope.

Thanks!

[murphy625]

Well I am back with this same topic again so I decided to just add to this thread.

I have decided to spend the money on scope.. I am VERY familiar with the techtronix model 465 (I think).. It looks just like the scopes I used to repair and calibrate.

My question is how much should I expect to spend for the 465 models? Also, if I get a bum one, what is the average repair costs and who repairs these things? (I lack the proper equipment and 20 years has done a good job of erasing my knowledge of them)

I am seeing them go for about $200 on ebay.. Does that sound about right?

Thanks again for all the advice!
Murphy

[Al_The_Man]

.. It looks just like the scopes I used to repair and calibrate.
Also, if I get a bum one, what is the average repair costs and who repairs these things?

I am seeing them go for about $200 on ebay.

I thought you were answering your own question there for a minute

I would say with any equipment like this on ebay is to look at the sellers reputation and if he has negs, see how he handles them.
Also make sure that they show it fired up or promises it has been tested.
because something as heavy as this is not worth returning by the time you pay the shipping.
(I think a new set of tectronix leads are $200).
You don't need anything of super high frequency response for general servo trouble shooting. Nothing more than the 465 can't handle.
Al

[Dogsione]

If you find a place to repair these, I'd love to know.

I have a Tek465 that I bought off of eBay a few years ago when I was building a tube amp. Only one channel works well. It came with the manuals, so if you buy one that doesn't and need any sections scanned/copied, just let me know.

I bought probes from these guys:
http://www.probemaster.com/

100mhz probe sets are only $35.00.

Good Luck!

[murphy625]

If you find a place to repair these, I'd love to know.

I have a Tek465 that I bought off of eBay a few years ago when I was building a tube amp. Only one channel works well. It came with the manuals, so if you buy one that doesn't and need any sections scanned/copied, just let me know.

I bought probes from these guys:
http://www.probemaster.com/

100mhz probe sets are only $35.00.

Good Luck!

Did you know the scope would be bad or did you get burned on ebay?

I have bought HUNDREDS of things off ebay... I have sold a few small things also. I have gotten burned by UPS more often then the ebay sellers but an oscilloscope is a different animal than most items. (not possible to fix yourself unless your well equipped already).

What did you pay for it?

Also, what do you think of the other cheaper brands? I can buy one from BK almost new for the same price as an older 465.. But is the BK scope a piece of junk compared to even an older Tektronix model? I've been out of this game for way to long to go it alone. Need your advice.
And what about the other brands? How do you feel about them?
Do modern day scopes break down as often as the older ones?

Hmm... I don't want to spend $200 and get something that doesn't work right.

Thanks again,
Murphy

[Dogsione]

First off, I don't want to misrepresent myself - I know very little how to use this thing. I bought it for educational reasons to look at waveforms and see how the amp and speakers I was building actually worked. I haven't used it in a couple of years, but I would like to get it working right when it comes time to rebuild that amp... :wee:

If I remember correctly, I got a pretty good deal because I think the guy I bought it from mispelled "Tektronix" and it went under everyone else's radar. The price of $168.00 sticks in my head though this was in '98/'99.

If you're worried about getting a good deal, just be sure to read fully the descriptions and don't bid on one that is cryptic or incomplete. Write the seller and ask lots of questions. I don't remember how mine was described, but I don't recall feeling ripped off.

Now, I can't say the same for the guy who still hasn't mailed that computer I bought a month ago.:tired: I'll let you know how eBay/Paypal handles disputes like this...

Sorry I can't really answer the rest of your questions. I'm sure there are many here much more qualified. Good Luck!

[ViperTX]

So, ask for details like when was it last calibrated, are there any burn marks on the CRT...if they have probes ask the person to hook the probe to the calibrator and adjust it on each channel and take a pic. Generally when you start digging for info. you'll either get a funny feeling....like avoid this one.....or maybe if the price is right it's a good deal.

[murphy625]

Thanks for the advice from both of you two above..

I think the real reason I am so jittery about buying one off ebay is because of my previeous experience in fixing them. (its not possible to do trouble shooting on them without another scope in hand.)

Ok.. So I am going to look for a 465 or better. I figure I'll spend about $200 + shipping.

thanks,
Murphy

[Mat-C]

Cooling it on the expense: good idea, but I'm not going to listen to you on that point

Scopes: can't see that you need much in the way of bw. Even basic scopes go to 20 MHz, can't see you needing more than a hundredth of that for this kind of stuff.

Dual channel is very nice for comparing two signals (no other easy way to see phase etc). More channels are nice but the difference isn't so great, and you can always use a dual channel scope and swap probes over to compare ch1 to ch2, then ch1 to ch3 etc. Dual channel scopes tend to have better triggering and stuff, but then again triggering isn't hard on regular 5v 1KHz signals Mine is 4 channel and I regularly use 2, the other 2 exceptionally rarely and even then usually out of laziness rather than swapping probes.

10x (and 100x) probes not essential as you won't be dealing with high impedence circuits. All they are is 10x higher impedence with 10x less sensitivity. You adjust your scope sensitivity 10x to compensate.

In conclusion: for CNC work I'd suggest the cheapest 20 MHz dual channel scope you can find, with the cheapest probes that money can buy.

Tek scopes: the older analogue ones have services manuals online I think? Mine hasn't blown up yet, so I've got no idea.

[diyengineer]

Cooling it on the expense: good idea, but I'm not going to listen to you on that point

Scopes: can't see that you need much in the way of bw. Even basic scopes go to 20 MHz, can't see you needing more than a hundredth of that for this kind of stuff.

Dual channel is very nice for comparing two signals (no other easy way to see phase etc). More channels are nice but the difference isn't so great, and you can always use a dual channel scope and swap probes over to compare ch1 to ch2, then ch1 to ch3 etc. Dual channel scopes tend to have better triggering and stuff, but then again triggering isn't hard on regular 5v 1KHz signals Mine is 4 channel and I regularly use 2, the other 2 exceptionally rarely and even then usually out of laziness rather than swapping probes.

10x (and 100x) probes not essential as you won't be dealing with high impedence circuits. All they are is 10x higher impedence with 10x less sensitivity. You adjust your scope sensitivity 10x to compensate.

In conclusion: for CNC work I'd suggest the cheapest 20 MHz dual channel scope you can find, with the cheapest probes that money can buy.

Tek scopes: the older analogue ones have services manuals online I think? Mine hasn't blown up yet, so I've got no idea.

I'm currently searching online for a good deal on a used oscilloscope. Possibly a stupid question but when you actually tune your servos, where are you getting the signal to tune? From the actual servo or from the encoder signal?
I have 3 Viper 100 drivers, 3 larger keling servos, and 3 us digital E6 differential encoders. I see a lot of 20MHZ scopes online, that must be what the standard baseline scope?