Test Equipment: Oscillocopes

[TinselKoala]

It appears that the "Modify" button has disappeared, so I can't just edit my last post.
Sorry for my own stupidity in not checking the materials that I already have to see if I had the info that I needed before going and asking a bunch of unnecessary questions and taking up people's valuable time to read/reply to them.

Hey, no problem, don't put yourself down. I'm glad to share what I know, and to learn more from those who  know more than I do.

When I'm to a point where I know what I am doing, I will pay it forward and teach the next guy since you all are taking your time to teach me.  That's only fair.  Then when I am incorrect about something or leave out important info, you will only then have to take the time to add a little info.

Brian

[edit] - ahh I see now, apparently after a certain amount of time has passed, you are unable to edit your posts anymore... [end-edit]

-  I am looing at probes to order, and from what I gather, the lower the model number, the higher the quality??

Here are my options for the standard 1x/10x probes:
---T5100 - http://www.ebay.com/itm/HQRP-100MHz-Oscilloscope-Probes-fits-Tektronix-HP-T5100-X1-X10-New-/221690519344?pt=LH_DefaultDomain_0&hash=item339dc8df30

---P6100   - http://www.ebay.com/itm/Two-x1-x10-100MHZ-Oscilloscope-clip-probes-HP-Tektronix-/290374567712?pt=LH_DefaultDomain_0&hash=item439bac4720

---TP6100 - http://www.ebay.com/itm/Two-Oscilloscope-Scope-analyzer-Clip-Probe-x1-x10-100MHz-Kit-For-Tektronix-HP/291177486377?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D29170%26meid%3D8ad8e434a92c4ee9afad4dbc3106985a%26pid%3D100005%26rk%3D6%26rkt%3D6%26sd%3D220375454020&rt=nc

I think all three of those probe sets are exactly the same probes, just with different labels on them, from the same factory in China even. Don't be fooled by the "for Tektronix" line on the ads... these are just basic low-quality scope probes so you might as well find the cheapest seller. Sure, they are "for Tektronix"... also for Owon, Agilent, Rigol, HP, Siglent, BKprecision, LeCroy ..... get the idea?  I bought a couple of these not too long ago, I think at the 16 dollar a pair price point, and they are adequate for what I'm doing. I don't remember if they included the ground springpoint adapter in the package.
But see below.

All of them are 6Mhz/100Mhz except for the P6100's, which are 4Mhz/100Mhz.
All of them are X1 = 150VDC peak; X10 = 300VDC peak, except for the TP6100 which are 300VDC/600VDC.
My scope's Max Input Voltage is (dc coupled) 250V(DC + peak AC) or 500V p-p ac at 1khz or less;  (ac coupled) 500V (dc + peak ac) or 500V p-p ac at 1khz or less.
So, if I am correct here, If I want to be able to take advantage of the full ability of my scope with the 1X probe, I would want to choose the TP6100 probes?

I can think of no reason whatsoever that you would want to use a 1x probe on a signal of hundreds of volts amplitude. Generally you will use 10x attenuation all the time, unless the signal is _so small_ that it doesn't read well with the 10x attenuation setting.

Also, as for a HV probe -
http://www.ebay.com/itm/100MHz-High-Voltage-Oscilloscope-Clip-Probe-4000V-Alligator-Clip-Passive-P5100-/111586099163?pt=LH_DefaultDomain_0&hash=item19fb0cbfdb

Looks deadly all right. Not something I would use around here, though; I don't work on high-power commercial radio transmitters much these days.   

This is similar to the "P4100" 100x probe that I got, but from a different vendor:
http://www.ebay.com/itm/New-100MHz-2000V-High-Voltage-Oscilloscope-Probes-P4100-/380456973755?pt=LH_DefaultDomain_0&hash=item589500b5bb

http://www.ebay.com/itm/Tektronix-013-0290-02-Oscilloscope-Probe-Screw-On-Hook-Clip-Set-P5100-P5120-/321462078021?pt=LH_DefaultDomain_0&hash=item4ad8a20a45

YGTBKM !  Fergeddaboudit.

Should I wait til I can afford that one and the spring loaded hook tip, or just get one along the lines of a $30 2kV probe with all the accessories?
I also noticed that none of those probes come with the spring point ground fitting. Is that just something more for HV applications?

No, _not_  generally for HV, more for high _frequency_ testing of circuit boards with chips mounted to them and specific ground pads included to match the spacing of the spring clip.

But the 100x probe that I got from China did come with the spring clip, a surprise.

Brian


heres a laugh..... a 1,000X  40kV probe....http://www.ebay.com/itm/1000X-P5104High-Voltage-40KV-40000V-20MHz-Oscilloscope-Passive-Probe-Clip-/291119549732?pt=LH_DefaultDomain_0&hash=item43c813cd24     

LOL.

But your scope is a higher bandwidth scope. You probably should be looking for 200 MHz probes instead of the cheaper 100 MHz if you want to take advantage of the high frequency range of your instrument. I don't do much work with super fast risetime or high frequency signals so I am fine with the cheap 100 MHz probes (that really probably don't come up to that standard either.)

http://www.ebay.com/itm/New-200MHz-Oscilloscope-Clip-Probes-Free-Accessory-Pack-/380322063353?pt=LH_DefaultDomain_0&hash=item588cf623f9
http://www.ebay.com/itm/250MHz-2000V-2KV-High-Voltage-Oscilloscope-Probes-P4250-/120693956323?pt=LH_DefaultDomain_0&hash=item1c19eb9ee3

[Brian516]

It seems like you prefer that one specific seller out of Santa Clara CA.  Any particular reason?  Do you know that his products are US made, or at least not made in China?

You're probably right about the probes I linked to.... upon closer inspection, they do look EXACTLY the same....
One thing I did notice from the ones I linked to to the ones sold from your seller in Santa Clara - The ones you link to have a plastic cover around th BNC connector, and the ones I linked to have a cheap looking metal connector. With a close look at them, they look like the cheapest of cheap metal that looks almost like plastic! haha

Hmm..  $25 a piece though...  unless I can get a deal on two for 30-40, I can only get one for right now. The HV probe will have to wait.

I don't know if it's the probes causing me the issues, but I'll just give you a quick rundown on what my scope is doing.
First of all, I know for a fact that I need to take it apart and clean the cam-actuated contacts for the V/div switch..... When I have it on with a probe hooked up and to the calibration loop, it's quite iffy.  I have to fidget with the knob to get it to show a trace that matches what the probe book says it should be looking like. This sucks, because It's going to take me alllll day to do since I'm particularly anal about cleaning things like that, but I guess that's a good thing since I doubt I'll break anything.
I just need to go to Lowes and get some 100% pure Isopropyl Alcohol or Methanol. I doubt I'll find any camel hair brushes like the book recommends in "preventative maintenance" (hahaha - good ol' 1973 stuff....)   I've seen that most people use paper strips soaked in alcohol to do the job nowadays.

The next issue is that, with the probe hooked up the same way, when I turn the 'position' knob, and the trace goes below the middle, it starts "zooming", and also when it goes above about the 2nd horizontal division line above the middle.

Channel 2 shows a horizontal trace, but has almost no vertical...

And both the probes I have, when I hook them up to my multimeter (one lead connected to the hook tip, one lead held in the connector) and let it hang, and wobble it around, the resistance reading bounces around between 8-9.3 Mohms.  I don't think it's supposed to be doing that......    That's what makes me think I need to get some new probes before I can really figure out what issues my scope has. The upper part of the trace was going up and down the screen as I touched the ground clip a little, and same with the probe tip.   

I have a cousin that lives in town that used to work as an electrical engineer and can calibrate this guy and maybe diagnose all these issues for me... when I can manage to get ahold of him.  until then I'm just going to have to make due.  For now I'll focus on cleaning up all the switches and getting the new probes..

[Brian516]

The Santa Clara guy sells the cheap ones too.... exact same as the ones I was looking at, same price, too.

http://www.ebay.com/itm/2-of-x1-x10-switchable-100MHZ-Oscilloscope-probes-4-HP-Tektronix-RIGOL-OWON-600V-/121170319361?pt=LH_DefaultDomain_0&hash=item1c36505801

Take a GOOOOD look at the picture that shows the tag on that one.............. see anything a bit off?!?!??  lol....
He did a photoshop job over the "200Mhz" to make "100Mhz"   and same with the 6100 of "P6100"!!!   
How can we trust ANY of these ebay sellers!!??   I mean, it seems like I'm gonna get ripped off somehow anyway!

What's your trick to being able to tell what ones are the good ones and what ones are the Chinese ones? lol

These look to be almost the exact same ones, but a pair and for a bit less.
http://www.ebay.com/itm/New-200MHz-Oscilloscope-Clip-Probes-Free-Accessory-Pack-/320570609224?pt=LH_DefaultDomain_0&hash=item4aa37f4e48

It also appears your Santa Clara seller has another store, selling the same stuff but for more.... same one you sent me the link to, but for $5 more.
http://www.ebay.com/itm/New-200MHz-Oscilloscope-Clip-Probes-Free-Accessory-Pack-/320822113669?pt=LH_DefaultDomain_0&hash=item4ab27cf585

This whole ordeal for finding the best deal on a GOOD pair of probes is a huge pain.

[TinselKoala]

Hey, he's not "my" Santa Clara dealer, I just found the probes on Ebay listings.

The only way to tell if they are any good or not is to get them and check, I guess. Looking at the "feedback" for the seller is also good, if the seller has 98 percent or better positive feedback they are probably honest enough.

I don't think you'll be able to find USA-made probes for cheap prices like those, everything is made in China these days and the quality is improving.

You can just take a cliplead from the scope's calibrator output and connect to a bit of wire stuck into the channel input jack, use the 1x scope attenuation setting and read a signal that way. You don't even have to worry about the ground connection as it is already connected inside the scope. This should give you a stable signal you can test with.

From your description I can't tell what is going on, maybe you can shoot a video showing the settings and the scope's behaviour, using the calibrator connection for a signal to each channel. Yes, you can connect the calibrator to both channels at the same time this way.

Don't use Methanol, it is very toxic! Absorbs through the skin, and by breathing vapors, and burns with an almost invisible flame, you could set something on fire and not even notice it.  And you won't be able to get "100 percent" isopropyl unless you go to a chemical supply house. Just get a good grade of spray-on electro contact cleaner, like LPS brand from the car parts store,  or "Jiffy Bath" from GC Electronics, sold in electronics supply stores. Even a Radio Shack might have a good "tuner cleaner" or electro contact cleaner. These cleaners will lubricate as well as clean the contacts. Read and follow the directions on the can. I would be very surprised if you had to use even a piece of paper, after cleaning with these products. You might get a bit of paper stuck in a switch contact....

[Brian516]

I read the negative reviews for that seller in Santa Clara and they were all in the last year, a lot in the last 6 months.  I think I'm going to go with these:
http://www.ebay.com/itm/New-200MHz-Oscilloscope-Clip-Probes-Free-Accessory-Pack-/320570609224?pt=LH_DefaultDomain_0&hash=item4aa37f4e48

And in the "notes" section I'm going to nicely ask if they have any of the spring grounds, if they could toss a couple in with the probes.  Hopefully they do. If not, oh well.
All they sell is mostly scopes and testers, and they have 100% feedback score, top rated seller, etc etc. so hopefully I'll be all good there. 

I've been calling around and looking at the MSDS's for the cleaners, and all I can get here at auto parts stores, Grainger, etc is CRC Electrical Cleaner, which is more directed towards automotive plug connections.... Radioshack has Precision Electrical Cleaner all the way across town for 15 bucks, and theres another one closer thats going out of biz and 50% off everything, but all they have left is Deoxit ProGold which is a conditioner/enhancer, and the Deoxit PowerBooster is the cleaner.... so it looks like I'll be going across town...

I'm really not looking forward to the stress of pulling this scope apart and cleaning those contacts, but I know it has to be done, and I might as well do it before I take it over to my cousin and he can't give me a proper diag/calibration because of it..   LIFE...