Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Problem with tweezers or 2 irons for that matter is that most boards will be lead free solder and that is just a pig to work with, needs a load of heat and that can also lift a pad if your not careful.

[Cerebus]

what do you guys think about this one?  $167 delivered

https://www.ebay.com/itm/HP-3325A-Synthesier-Function-Generator-w-Power-Cable/254467450725?epid=1505466257&hash=item3b3f712765:g:VysAAOSwzwReCkQH:sc:FedExHomeDelivery!98408!US!-1

If it's working it looks like a bargain. I've got one and it's a nice capable unit if you don't need to go above 20MHz (there's a 60MHz range but you lose a bit of the spec. by using it - which may or may not be an issue for you, check the datasheet if you think it might).

[tautech]

Problem with tweezers or 2 irons for that matter is that most boards will be lead free solder and that is just a pig to work with, needs a load of heat and that can also lift a pad if your not careful.

Then you flood the pads with leaded solder and proceed as usual....but you already knew that.

[Kosmic]

We could go round and round on this forever.

These are my 2 "transfer" standards. They are from 2 entirely different lots which gives some better level of credibility. I have no reason to doubt their accuracy.

The two 8800A's agree with both of them, 100%. The Siglent is consistently off by what I mentioned before. I think it's unlikely (but not impossible) that the Siglent is right and everyone else is wrong. Which way do YOU want to bet the farm? 

It's also important to note that those AD584 voltage ref are quite sensible to temperature.

Example, I was logging the 10V output over 2 days. Temperature variation was about 2 deg (please ignore the misbehaving hp 34401a)

[beanflying]

Part of the 'fun' of the last few PPM's or worse sub PPM's is is it the reference or is it the meter that is drifting with Temperature  My currently running testing of 34401A and 735A is down to the level of the last few PPM's per 5C which in reality is more than I need already but not enough for using to recal other gear. SO......

I have a whole set of 'better' voltnuttery to do over the next few months. The Resistor sets I have inbound for making a couple of LTZ1000 VRefs will be going into a converted Wine fridge along with my collection of Standard Cells and a couple of simple LM399 VRefs. The plan is to set up one of my 34970A Loggers and a little Atom PC. Unfortunately the Fridge is to small to fit the Logger inside without some more mods. Work in progress 

[mnementh]

...With apologies for the extended absence. I see mnem has turned into a Canadian while I was away. 

Welcome back, ya hoser! 

For a while I headed down the 'volt-mutt' rabbit hole, and still have a leg in there to tell the truth.
I ended up with a 3458 and about a dozen ltz10000 references of different construction. I am still doing a long term experiment with the references.
Reliable and reasonably accurate and repeatable voltage readings down to the 10s of uV (in the 10V range) are pretty achievable and 6 1/2 dmm can get there, eg my 34461A. Those meters are I think very good value for money.
Below that starts getting crazy,
1 Most LTZs do drift esp early on (month or so) and I suspect so do all the other components. Of my voltage references, two look pretty good, ie not much drift, lowish temp co-efficient.
2 Room/lab/leads etc starts getting crazy, a EMI noisy laptop can blow readings in my set up by many uV.
Volt nuttery is and was for me a learning experiment - in all seriousness I can't recall ever having to measure a voltage better than a few 10s of mV.
The other issue with 'calibration' is that it is not a static or one-off event - everything drifts and that needs to be a 'known', hence most reference meters have a 'calibration cycle'. Part of my reasoning with so many volt references was to be able to reduce the cost of repeated formal (expensive - and risky - shipping a 3458 800km) calibration.
Rob

No, no, no... you have that wrong. A volt-mutt is the polar opposite of a volt-nut. The guy for whom "Fluke sez BAM!!!" is good enough... preferably 4-5 digit Flukes at most. You've fallen so far down the rabbit-hole no mutt can dig you out. 

mnem
But hey... it sure is soft and fuzzy down there...

[mnementh]

Problem with tweezers or 2 irons for that matter is that most boards will be lead free solder and that is just a pig to work with, needs a load of heat and that can also lift a pad if your not careful.

Then you flood the pads with leaded solder and proceed as usual....but you already knew that.

There's a difference between large quantities of heat and higher intensity heat. If you're trying to make up for a deficiency in the former with the latter, or if your PCB has ALREADY been cooked to death (or is just cheap-ass shit to begin with), THAT is when the heat required becomes a problem. Like tautech sez... flood the pad with flux & leaded solder to decrease the melting point of the solder.

I would cut the cans off a mm or three above the board with flush-cutters and dissect them before I'd ever do that ghetto-booty-fab shit twisting them off with pliers.

mnem

                proper booty fab

[med6753]

No, no, no... you have that wrong. A volt-mutt is the polar opposite of a volt-nut. The guy for whom "Fluke sez BAM!!!" is good enough... preferably 4-5 digit Flukes at most. You've fallen so far down the rabbit-hole no mutt can dig you out. 

mnem

Woof! And........



 

[madao]

Actually , i repair  TDS540  with less capacitor plague.

It looks good, CPU Board no fail  despite empty batterie NVSRAM.
Acquisition board has minor fail,  shut up , because i must sleeping.

Whats your technique for removing these capacitors because those little bastards always give a bit of grief getting them out.

I use two soldering iron to removing of capacitor.

I watched a video done by Mr. Carlson repairing a Tek scope with these surface mount can caps, and he was just grabbing them with a pliers and twisting them off their leads, then desoldering the lead stubs remaining on the board.  I've tried it a time or two since with good results, though it does still make me a tiny bit nervous about tearing up pads.  So far so good, though, so that concern is decreasing with experience.

FWIW.

-Pat

I saw that, seemed to work surprisingly well, and Paul hasn't steered me wrong yet.



sigh, the forum is modifying the link and I can't make it work for the life of me

Please, never, never, never try to do that. You are going to break a board. Can't believe he did a video recommending this technique. You could also try to throw the board on the ground until the cap come off ?

Like bd139 recommended, use tweezers, 2 irons. Also hot air (with controlled temp) was always working fine for me.

Yes, i have doing at this methode with plier, but only if  capacitor plague is extreme. Solder is crumbly. But,  At this case, you can trow  unit away, to much etched trough pcb trace.

In  this case with TDS540 is  capacitor plague minor..  CPU Board doesn't have  one  etched throurgh pcb trace.   Acquisition board, probably  only one or two.  Because,  preowner has buy it at long  since  time ago and didn't  power it, after one error message came.

This is why,  TDS540  survive  with minor damage. I always recommend: Never power it , if  unit has  SMD capacitor plague.  Remove all  bad capacitor and wash him well with disc detergent.  This is a important step, else you crow too soon.
Actually has TDS540 one Error message, of coruse it is cryptic. 

[madao]

That was a labour of love madao! Were all those capacitors really bad?

All capacitor leaks their eletrolytics, common failure of early SMD eletrolytics.

[med6753]

That was a labour of love madao! Were all those capacitors really bad?

All capacitor leaks their eletrolytics, common failure of early SMD eletrolytics.

Believe it or not I came face-to-face with someone here on the blog who questioned how we came to do mass capacitor replacements and considered it "uneducated" troubleshooting.   

Even sighting examples such as vacuum tube equipment with wax caps and dry electrolytics, 1970 - 1980's vintage beaded tants, etc did not convince him otherwise. 

[worsthorse]

That was a labour of love madao! Were all those capacitors really bad?

All capacitor leaks their eletrolytics, common failure of early SMD eletrolytics.

Believe it or not I came face-to-face with someone here on the blog who questioned how we came to do mass capacitor replacements and considered it "uneducated" troubleshooting.   

Even sighting examples such as vacuum tube equipment with wax caps and dry electrolytics, 1970 - 1980's vintage beaded tants, etc did not convince him otherwise. 

This is one of those things that cyclically arises on the tekscope lists, inevitably in the form of a newcomer being given an earful after asking whether a mass capacitor replacement for some piece of gear is necessary. 

As always, it depends. Sometimes it is just the thing to do, sometimes it is uneducated troubleshooting.  Guess it depends if you know why you are doing it.

[madao]

By this case ist mass replacing of SMD eletrolytics correct way and important: or it break again down and you waste much time to fix. Because leaked eletrolytics etch PCB trace.

 Same: Newcomer didn't wash PCB and didn't check PCB trace and cries: it is not fixed. / It is broken again.

Grettings
Matt

[beanflying]

On my list of non essential but desirable tools in my next life is a surface grinder. But Good enough for 'Stralia a strip of Paper on last weeks very flat and solid workbench build

#5 was a new/old purchase last week and the #4 was Dad's their soles were due for a once in a several decade tune up. Both are now sporting uber sharp, accurate and square blades after an application of Tautech's little gift some elbow grease and some TLC on the adjustment front.

Interesting the hardness difference in the Cast Iron too. The Pommie made sole is much harder than the Australian made one. Good and bad about both but give me the soft one to resurface.

[tautech]

Good to see it earning its keep Bean after 30+ years sitting idle in my carpenters carryall. 

[orin]

I have one of those standards like the one with the faded year.

When I got it, it read 20 ppm low for 10V on a Fluke 8845A.  The Fluke was within a couple of ppm of my 731B standard at 10V.

Over 87K samples and a temperature range of 19.6 to 25 deg C, I got:

Min 10.00114, Max 10.00123, Avg 10.00118.  The value written on the standard was 10.00140.  I was disappointed.

The numbers on the standard are as good as the adjustment of the 34401A they used to measure it and the 34401A is spec'd at +/- 35 ppm basic accuracy.

I see no reason to disbelieve the Siglent.

And this is exactly why I purchased a 2nd reference. I wasn't sure if I could trust it. Now is it possible that BOTH are inaccurate? Of course but based upon what I've observed, and to the limits of my equipment, I don't think so. There appears to be this perception that I'm a loose cannon and I make decisions in a vacuum. Just the opposite. I think I'm very meticulous and draw valid conclusions based upon what I test and observe.

But both the references were measured with the same 34401A...  Each is no better than the 34401A that measured it.  Without a traceable cal of the 34401A, we can't really draw any conclusions.

[orin]

This is why I mostly use the fluke 87 

Me too - if not the Fluke 111 which I like better when if has enough resolution for the measurement.

It was adjusting an 8568B that actually required more resolution than the 111.  The 87 came much later.

[McBryce]

Category: Simple but useful

3D printed pointer for pics -

(Attachment Link)

That's a cool idea. Must make one.

Please, never, never, never try to do that. You are going to break a board. Can't believe he did a video recommending this technique. You could also try to throw the board on the ground until the cap come off ?

Like bd139 recommended, use tweezers, 2 irons. Also hot air (with controlled temp) was always working fine for me.

I've twisted off caps for years without an issue. It's important not to pull the cap, just twist and never twist a cap that has spewed electrolyte onto the pads, they will lift immediately. Tweezers / hot air is fine, but there are many cases where the tweezers won't fit and hot air could damage very close plastics.

McBryce.

[Specmaster]

I have one of those standards like the one with the faded year.

When I got it, it read 20 ppm low for 10V on a Fluke 8845A.  The Fluke was within a couple of ppm of my 731B standard at 10V.

Over 87K samples and a temperature range of 19.6 to 25 deg C, I got:

Min 10.00114, Max 10.00123, Avg 10.00118.  The value written on the standard was 10.00140.  I was disappointed.

The numbers on the standard are as good as the adjustment of the 34401A they used to measure it and the 34401A is spec'd at +/- 35 ppm basic accuracy.

I see no reason to disbelieve the Siglent.

And this is exactly why I purchased a 2nd reference. I wasn't sure if I could trust it. Now is it possible that BOTH are inaccurate? Of course but based upon what I've observed, and to the limits of my equipment, I don't think so. There appears to be this perception that I'm a loose cannon and I make decisions in a vacuum. Just the opposite. I think I'm very meticulous and draw valid conclusions based upon what I test and observe.

But both the references were measured with the same 34401A...  Each is no better than the 34401A that measured it.  Without a traceable cal of the 34401A, we can't really draw any conclusions.

If you check the labels, they might well have been checked against a 34401A but certainly not the same 23301A and also one was @21C and the other @25C

[grizewald]

Is that a Bodnar pulser I see there on your bench grize?

It is indeed! Great little device.

[FransW]

One should realise that absolute measurements do not exist (yet?). Our knowldge of physics just does not allow this (Planck, Heisenberg).
Have a look at the shortest possible time-step, it is in the region of 10 to the power of -44 seconds.
Which is way beyond our, NIST's and BIPM's capabilities.
Use measuring equipment to measure to the accuracy level you require and forget to create your own calibration lab. It just requires too much labour and capital for all practicle purposes.
Unless of course your happiness level can not be satisfied otherwise.
And stay away from believing. Thinking seems to me a better approach.
Measuring involves knowledge and experience on the following subjects: accuracy, uncertainty, repeatability, resolution, traceability, error, type of error, shannon criteria, sampling type, data processing, traceability to standards, etc., etc.
Cailibrating your equipment costs money. You have to pay for this, either by using a calibration lab or setting up your own calibration lab. Or just have fun getting into it as deep as your practicle knowledge and requirements allow.
Have fun, Frans

[grizewald]

what do you guys think about this one?  $167 delivered

https://www.ebay.com/itm/HP-3325A-Synthesier-Function-Generator-w-Power-Cable/254467450725?epid=1505466257&hash=item3b3f712765:g:VysAAOSwzwReCkQH:sc:FedExHomeDelivery!98408!US!-1

It's a nice piece of kit, although the puke yellow buttons from being exposed to the sun would put me off that particular example. It doesn't have the OCXO option fitted either, so you might end up looking for one of those as well if the built-in reference is anything like the disaster they put in the 5334.

[grizewald]

Mine hummed. This improved a bit when I took it completely to bits to do the RIFAs in it. You did replace them didn’t you? 

Basically tighten the big screws holding it down and it’ll compress the laminations some more.

Edit: and oh yes the built in TCXO is total crap. Very disappointing. My 5316 which has the basic crystal oscillator is more stable!

I'll try torquing down the transformer a bit more when I take it apart to fit the OCXO. The noisiest is actually the 3325 and that really needs to stay plugged in all the time to keep the oven hot.

The power input circuitry is different between the A and B versions of the counter. Mine doesn't have the PCB mounted X capacitors like your B model, they are included in the filter box that sits behind the power socket and I've not taken that apart to check it yet.

[BU508A]

Anybody in need of a 33GHz scope from Keysight?
Costs only 192000,- Euro plus VAT and shipping.

https://www.instrumex.de/en/8065

[Cerebus]

what do you guys think about this one?  $167 delivered

https://www.ebay.com/itm/HP-3325A-Synthesier-Function-Generator-w-Power-Cable/254467450725?epid=1505466257&hash=item3b3f712765:g:VysAAOSwzwReCkQH:sc:FedExHomeDelivery!98408!US!-1

It's a nice piece of kit, although the puke yellow buttons from being exposed to the sun would put me off that particular example. It doesn't have the OCXO option fitted either, so you might end up looking for one of those as well if the built-in reference is anything like the disaster they put in the 5334.

My 3325A seems nice and stable without the OCXO option, but we are talking a sample size of one and perhaps I just got lucky.