Test Equipment Anonymous (TEA) group therapy thread

[Vince]

Yes those on TEA with a fancy expensive DMM could do that I guess...

As far as I am concerned, since the aim to test my DMMs not the Vref, this means this Vref is good enough to check my best DMM, hence all of my 25 DMM collection, so that's cool.

I am keeping this little Chinese box 

[tggzzz]

Yes those on TEA with a fancy expensive DMM could do that I guess...

As far as I am concerned, since the aim to test my DMMs not the Vref, this means this Vref is good enough to check my best DMM, hence all of my 25 DMM collection, so that's cool.

I am keeping this little Chinese box 

Boring

[Vince]

Yeah sorry, just send me your  0.000000001 % DMM and I will redo the experiment I promise !! 

[Robert763]

Just received a 100x scope probe, NOS, reasonable money.

It's an Elditest GE 3121, 150MHz, 2kV, though I don't want to ever be within a mile of anything oscillating at that frequency and magnitude! Fabrique en Allemagne, so decent quality I should think.[/color=teal]

Worthless unless you have the frequency derating chart.

Worthless how? I already said I won't be going anywhere near frequencies like that at higher voltages. The highest it'll see is the inside of a smps. In any case the datasheet will be available from the manufacturer I'm sure; Germans are fastidious about such things.

Do download it and examine the frequency derating and you'll see what I mean. They rolloff big time at just a few MHz which of course you won't see in the std SMPS.
But good on ya for getting a 100x HV probe and playing it safe. 

OEM appears to be French. Roll-off starts about 300 kHz. Down to about 300 V at 8 MHz. Manual here:
https://bkpmedia.s3.amazonaws.com/downloads/manuals/en-us/GE3121_manual.pdf
Current model @ £79 from Farnell https://uk.farnell.com/elditest/ge-3121/probe-osciloscp-2kv-150mhz-x100/dp/1532989

Note that the BNC is not insulated. The manual says: "Probe assemblies must not be used for measurements on mains circuits."
It's IEC1010 CAT I which is not for use on ciruits conneted to the mains. I've always thought this misleading because most people think "CAT" raings are for mains use.
This probe is not suitable for use on the primary circuits of mains SMPSUs

Nice catch. 
Had me look up the ones we carry and they are CAT II  again.
http://www.pintek.com.tw/productDetail/land-ctop-2/index/pscsn/17073/psn/19272

Not sure I understand... your website says CAT 2 only for DC, but CAT 1 for AC. Mains is AC of course, so CAT 1...
No ? 

Sorry if I misread you or Rob 

Looks like a mistake on the website.
Manual says CATII 1500 V (AC peak + DC) http://www.pintek.com.tw/customer/pintek/upload/CP3308R.pdf . The datasheet says CATII 1500 V and CATI to 2000 V. both these would be AC peak + DC, this is standard for IEC1010.
Edit http://www.pintek.com.tw/customer/pintek/upload/CP-3308R-spec.pdf

[Saskia]

checked up on my appartment. Hope to notarize the sale by end of next week.

[Robert763]

Or just permanently charge the battery.

That's assuming the device is designed to turn the auto-off feature off, when the charger is plugged in. I don't know that.

Anyway, that was to reply last nights comments.... now after a good night of sleep I have some good news :

I did decided to conduct the experiment, and turned the Vref on before going to bed. Just at midnight.

Now I just woke up. At 9h00, the Vref is STILL up and running, so no auto-off features it looks like ! 
It's my DMM that turned itself off...

So I have now two data points, 9 hours apart.

How much drift ? Zero.

I set it up to 2.5V because a) according to the datasheet of the AD584K that's the output that gives the best performance and b) it's the only output that allow me to use the full 5 digit resolution of the DMM, making it is easier/more likely to catch drift.

So, at power up got 2,5015 (2.5013 on the sticker).
9 hours later overnight, DMM still reads 2.5015....

Spec, for the AD584 alone, is "25ppm/1000hours". Presumably they mean the first 1000hours, since usually the drift is assumed to reduce over time - hence the usual sqrt(1000hours) LM399 specification.

So, you should keep it powered for a few months and/or get a better well-aged meter.

Of course both could be drifting in the sam direction. You need at least one more reference. 

[m k]

That's assuming the device is designed to turn the auto-off feature off, when the charger is plugged in. I don't know that.

Press it ON longer.

[BU508A]

Or just permanently charge the battery.

That's assuming the device is designed to turn the auto-off feature off, when the charger is plugged in. I don't know that.

Anyway, that was to reply last nights comments.... now after a good night of sleep I have some good news :

I did decided to conduct the experiment, and turned the Vref on before going to bed. Just at midnight.

Now I just woke up. At 9h00, the Vref is STILL up and running, so no auto-off features it looks like ! 
It's my DMM that turned itself off...

So I have now two data points, 9 hours apart.

How much drift ? Zero.

I set it up to 2.5V because a) according to the datasheet of the AD584K that's the output that gives the best performance and b) it's the only output that allow me to use the full 5 digit resolution of the DMM, making it is easier/more likely to catch drift.

So, at power up got 2,5015 (2.5013 on the sticker).
9 hours later overnight, DMM still reads 2.5015....

Spec, for the AD584 alone, is "25ppm/1000hours". Presumably they mean the first 1000hours, since usually the drift is assumed to reduce over time - hence the usual sqrt(1000hours) LM399 specification.

So, you should keep it powered for a few months and/or get a better well-aged meter.

Of course both could be drifting in the sam direction. You need at least one more reference. 

At least three references are needed to be sure. I recommend five. At least. 

[mnementh]

Or just permanently charge the battery.

That's assuming the device is designed to turn the auto-off feature off, when the charger is plugged in. I don't know that.

Anyway, that was to reply last nights comments.... now after a good night of sleep I have some good news :

I did decided to conduct the experiment, and turned the Vref on before going to bed. Just at midnight.

Now I just woke up. At 9h00, the Vref is STILL up and running, so no auto-off features it looks like ! 
It's my DMM that turned itself off...

So I have now two data points, 9 hours apart.

How much drift ? Zero.

I set it up to 2.5V because a) according to the datasheet of the AD584K that's the output that gives the best performance and b) it's the only output that allow me to use the full 5 digit resolution of the DMM, making it is easier/more likely to catch drift.

So, at power up got 2,5015 (2.5013 on the sticker).
9 hours later overnight, DMM still reads 2.5015....

Spec, for the AD584 alone, is "25ppm/1000hours". Presumably they mean the first 1000hours, since usually the drift is assumed to reduce over time - hence the usual sqrt(1000hours) LM399 specification.

So, you should keep it powered for a few months and/or get a better well-aged meter.

There's been a considerable amount of discussion over these Chinesium AD584 standards in here... IIRC, it was at one point the consensus that they appeared to be made with reclaimed AD584s, so likely were well-aged before they were ever built.

mnem

[Specmaster]

The Thandar SC110 arrived this morning, didn't look too bad, battery door is missing, and the battery carrier had 4 C cells in it, looking the worse for age but no corrosion, so that's a bonus. Took a punt on it and removed said batteries, all were well and truly flat, just 1.7v, all 4 connected in series  . Connected it up to my bench supply and switched on, there is a beam but no sweep, I can move the spot sideways and up/down, but movement to the right is restricted to half way. Vertical amp is working OK when connected to the scopes test point and the beam is reasonably bright, so that's a relief, always a bit disconcerting when buying something that is not shown powered up.

So it's now time to get the manual out and dissect this puppy and look for signs of problems on the inside. Photos and more to follow in due course.

[mnementh]

Yes those on TEA with a fancy expensive DMM could do that I guess...

As far as I am concerned, since the aim to test my DMMs not the Vref, this means this Vref is good enough to check my best DMM, hence all of my 25 DMM collection, so that's cool.

I am keeping this little Chinese box 

Boring

Yeah sorry, just send me your  0.000000001 % DMM and I will redo the experiment I promise !! 

Hark! What sound doth across yon internet break...? 

Is that the soft "woof!" of a fellow voltmutt I hear...? 

mnem
Waitaminnitt... since Vince is French, wouldn't that be "weuf...!" ...?   

[mnementh]

Marco Reps is selling some of his stuff:

https://www.ebay-kleinanzeigen.de/s-bestandsliste.html?userId=15084259

NAWTS

Not the custom 8.5 digit CERN multimeter (I would buy that  ), and the Keithley 155...  though it does make you wonder what he is collecting funds for.

He's finally building his Quantum Orgasmatron... 

mnem
Yes, you may touch it...   

[mnementh]

It's just that... well... I've run out of patience for having to open the hood and twirl wrenches every few days. Same is true of my vehicles as well; which is why when I left Houston, I left Franken-Cruiser™ behind. 

mnem
I think I've done enough penance for being born with The Knack.

Perhaps that is so. What I'm thinking is that once one gets into running such things on a daily basis, sortakinda "critical mass", it becomes second nature. And you indicate you're not there. (A lot of "second nature" of course us internalizing the chores as "natural". Which may or may not be a Good Thing... )

There's a fair amount of truth in that. 

Of course, the other choice is fully automated maintenance behind the scenes so you don't have to think about it; what I was bitching aboot the other day: My old gaming rig decided that overnight, just before I wanted to go play in the Discord, was the perfect time to download and update to a major release, thereby leaving me fuming for 20 minutes while it hashed the poor old spinning rust HDD to death on a forced reboot I had no choice about and my sandwich/coffee got cold. 

mnem
"It's all BS  ; pick a layer and dive in." ~mom

[Vince]

Yes those on TEA with a fancy expensive DMM could do that I guess...

As far as I am concerned, since the aim to test my DMMs not the Vref, this means this Vref is good enough to check my best DMM, hence all of my 25 DMM collection, so that's cool.

I am keeping this little Chinese box 

Boring

Yeah sorry, just send me your  0.000000001 % DMM and I will redo the experiment I promise !! 

Hark! What sound doth across yon internet break...? 

Is that the soft "woof!" of a fellow voltmutt I hear...? 

I usually kinda can make sense of Dwagoni speech, but I ahjve to say here it's getting harder than usual. I hope you did not insult me or anything naughty without me even realizing it...   

... but... thanks for the link, shows that my old French FERISOL Nixie counter made it in this POI post !!!     

mnem
Waitaminnitt... since Vince is French, wouldn't that be "weuf...!" ...?   

There is no French for this "word". We simply don't make that kind of noise/sound over here, it's very specific to English speaking areas...

[Vince]

I am just done oiling my brand new oak parquet in the bedroom.

After 2+ weeks patiently waiting for some moron to give back the machine to the rental agency.... and him still not returning it, I got bored and drove 20 miles to find another agency that did have one.

It's a total disaster. First the oil that was supposed to be good for 80m2, was juuuust about enough to cover the 10m2 of that room. Manufacturer, Rubio, is top quality stuff well used and known by wood workers in Frog land. They all say they get the 80m2 advertised... but I got only 10m2 out of it. Oil so sirup-like, so thick, even the micro-fibre rectangular flat "broom" I used (recommended by Rubio for Joe public), could not spread the oil because it was so sticky. I could push the oil with it, using a lot of force, but pull the broom towards me or make it go sideways, the joint of the broom would go haywire every time.

So a pain to spread. The can says it's "pure".. but they don't say to dillute it, at all. The instructions just say to pour a liiiiitle bit then spread it and then wipe the excess... my ass.
Waited a few minutes as per the instructions, then went to use the machine to soak the excess and buff it off..... bad idea.
The machine is too powerful, 1500W IIRC, and the oil is sto thick and sticky, it's like glue, sirop d'érable, what have you... so the huge buffing pad gets so much grip on the floor that the machine develops a tremendous amount of torque... I am big guy, twice your average Joe, but this thing was un-con-tro-lable.

So I ended up pleasing the Cerebus divinity. Had to do SOMETHING to get out of this mess... so I sacrificed a white bathroom towel and tried to soak the excess oil by dragging the towel, walking on it. didn't work... was so sticky that even though I am fucking heavy, too much to admit, my feet could not move the towel. I had to go Cerebus way kneel on the floor... knees have much less contact area than my feet So it worked at last, I was able to rub the towel and move around the room. Much sweat later, I realized it looks nice as it was and didn't feel the need to use the machine anymore... it looked mat, an even finish, looked nice... but since I had the machine around an paid for it, I wanted to have my money's worth. So I gave it another try.. With most of the sticky oil now gone, it was A LITTLE BIT more controllable... but still nowhere near enough to call the machine useful. You can't steer it, too much grip with that buffing pad on the oil. Machine just keeps spinning CCW and after a split second it bangs onto the dry wall, almost ripping a chunk off of it. Machine just keeps "driving" over the mains cable/cord, over and over again, no choice.. and 50% of the time the cable gets caught between the pad and the platter that it's mounted too. Before you know it the cord is wrapped around the machine and pulls the plug off of the wall socket... then you have to remove that platter an try to un-entangle the cord.. then the platter as it comes off, impacts the parquet, leaving black marks on it, ruining your nice expensive parquet... Oh and to finish, the wheels leave traces on the parquet so you need to buff that off as well, but of course it's a never ending game...

So no... no no no ... NO !

I know understand why the agency had only ONE of these machines, and the guy told he had been working there for 3+ years and I am the FIRST guy to ask for this machine ! 

I think it could have worked with a machine made specially for parquets.... they list one on their website. It's much less powerful, only 500W not 1500W, and has 3 small 150mm pads arranged in a triangle, rather than one huge 400mm circular pad. Also has not plastic wheel at the back so it can't leave any nasty traces on the parquet. But they have only ONE such machine available, in the entire region, and it's in Le Mans !! That's 250+ kms away or something !!!   

So all in all... it was quite an experience. Next time I oil that parquet (recommendation are once or twice a year I gather), I will just do it manually like I just did... sacrifice a towel, and kneel down, and rub, rub...     Thank goodness the room is only 10m2 ! 


What does that have to do with TE ? Well it's obvious : short term this will be my bedroom, but longer term bedroom will I think be relocated in the attic and the current bedroom will be used for the lab, allowing it to move out of the living room...
so there will be TE in this room one day.

Instructions say to leave it alone for 6 to 8 hours before I can walk on it, and once week before I can use water/detergent to clean/maintain it.

Will allow extra margin just in case... will wait 'til tomorrow...

Then I can re-install the door, then start searching for a place that can make me plinths of the dimensions and style I want.

Oh, now that the towel and micro-fiber "broom" pad are soaked with oil... I made sure NOT to soak them with water... I WANT to see if they will catch fire !   
Will leave them outside of course... don't want to burn the lab and house down !

[tggzzz]

Or just permanently charge the battery.

That's assuming the device is designed to turn the auto-off feature off, when the charger is plugged in. I don't know that.

Anyway, that was to reply last nights comments.... now after a good night of sleep I have some good news :

I did decided to conduct the experiment, and turned the Vref on before going to bed. Just at midnight.

Now I just woke up. At 9h00, the Vref is STILL up and running, so no auto-off features it looks like ! 
It's my DMM that turned itself off...

So I have now two data points, 9 hours apart.

How much drift ? Zero.

I set it up to 2.5V because a) according to the datasheet of the AD584K that's the output that gives the best performance and b) it's the only output that allow me to use the full 5 digit resolution of the DMM, making it is easier/more likely to catch drift.

So, at power up got 2,5015 (2.5013 on the sticker).
9 hours later overnight, DMM still reads 2.5015....

Spec, for the AD584 alone, is "25ppm/1000hours". Presumably they mean the first 1000hours, since usually the drift is assumed to reduce over time - hence the usual sqrt(1000hours) LM399 specification.

So, you should keep it powered for a few months and/or get a better well-aged meter.

Of course both could be drifting in the sam direction. You need at least one more reference. 

Yup. That's why patience is a virtue in this game.

I have a Transcell II (excellent, well aged), a Trancell VTS/6 (1.5ppm popcorn noise), a Fluke 515A, a Cropico ESC1, and several noiseless primary references that I use as temperature sensors.

No, I'm not going to bid for the Fluke 332B even though it isn't far from here. Too many carbon composition resistors for my taste.

[tggzzz]

Yeah sorry, just send me your  0.000000001 % DMM and I will redo the experiment I promise !! 

Send me your Vref, and I'll use my Solartron 7081, Agilent 34410A, and compare it with my references I'll use my Julie Research VDR106/7 to get the intermediate voltages

[mansaxel]

<snip>

and my sandwich/coffee got cold. 

Huh? Such a forced pause is the exact moment one chooses to indulge in coffee and sandwich. If something makes me engage and dive in, I'm all likely to forget my cuppa, and many a stone cold half-empty coffee cup has been found in the workshop because I went a-tinkering on a tangent.  When Computer Says Wait, no cup is left undrained, though.

TE maintenance day:

Dragged, somewhat inspired by Vince finding a reference, my DMMCheck down from its perch, and started to go through my Fluke side-buttons (8020, 8022A, 8060A, one of the two I've got), because it felt like a nice diversion. Realised that neither 8020 nor 8060 would measure Ampère.  The 8020 has only one fuse, so that was easy. The old one had disintegrated from current, age or both, so that one end cap was loose and o/c. New one fitted.  The 8060A was a bit more resistant, the accessible fuse in the battery compartment was OK. Opened up and poked around; but discounted the large fuse for a while. Then decided to check it. O/C.  Dafuq? Oh, well. Haven't got one of those, so had Middle Boy press down on another size-incompatible fuse in the well while I checked the current mode, and of course, there's the problem. 1,0003mA measured.

So, time to find a proper fuse. BBS-3 3A 600V according to my local-language folder.

[Vince]

That's very nice of you ! Sadly the cost to ship it and get it back, with import shit on top of it, would cost me more than the Vref is worth... I don't have money to burn at the moment...

Thanks for the offer though ! 

[mnementh]

The Thandar SC110 arrived this morning, didn't look too bad, battery door is missing, and the battery carrier had 4 C cells in it, looking the worse for age but no corrosion, so that's a bonus. Took a punt on it and removed said batteries, all were well and truly flat, just 1.7v, all 4 connected in series  . Connected it up to my bench supply and switched on, there is a beam but no sweep, I can move the spot sideways and up/down, but movement to the right is restricted to half way. Vertical amp is working OK when connected to the scopes test point and the beam is reasonably bright, so that's a relief, always a bit disconcerting when buying something that is not shown powered up.

So it's now time to get the manual out and dissect this puppy and look for signs of problems on the inside. Photos and more to follow in due course.

   

Great! Now you need the whole set! 

BAMA has the SM, but I found a better copy here with actually legible schizzmatics:

https://k1.spdns.de/Vintage/Sinclair/Other%20Inventions/Other%20Electronics%20Products/Thandar%20SC110A%20Oscilloscope%20Service.pdf   

It's too big to post here for posterity, but I did observe due diligence and eMailed Ed a copy so he can update BAMA.

Interesting... it appears Sinclair's MicroVision TV uses the same plate-deflection CRT:

http://lushprojects.com/blog/2015/07/thandar-sc110a/

mnem

[Vince]

The schematic for the time base and Horizontal amplifier are simple enough, and probably use off the shelf components given the specs of the scope (2MHz...).. so this scope will probably be working again by this evening !!!

[mnementh]

Hark! What sound doth across yon internet break...? 

Is that the soft "woof!" of a fellow voltmutt I hear...? 

I usually kinda can make sense of Dwagoni speech, but I ahjve to say here it's getting harder than usual. I hope you did not insult me or anything naughty without me even realizing it...      ... but... thanks for the link, shows that my old French FERISOL Nixie counter made it in this POI post !!!     

mnem
Waitaminnitt... since Vince is French, wouldn't that be "weuf...!" ...?   

There is no French for this "word". We simply don't make that kind of noise/sound over here, it's very specific to English speaking areas...

When I want to poke fun at a frog, you'll know it...




I mean, I know it's so much work to scroll down the TEA Glossary I linked to; so here, let me do it for you... 

"voltmutt" doesn't make sense... you mean as opposed to this "word"...?   


mnem


Hmmm... is that the excited yapping of a French poodle I hear...?       

[ch_scr]

I am just done oiling my brand new oak parquet in the bedroom.
(...)

I am fully out of my waters here, but to me, it sounds like the oil had gone off, started to polymerize, if you will, making it high viscosity?
Was it over its "best before" date, or stored too hot, or maybe container damaged and leaked air into it a tiny bit?
But good job anyway getting it done 

[Cerebus]

I've always thought this misleading because most people think "CAT" raings are for mains use.

The whole CAT rating thing is a classic example of a system designed to reduce a lot of complex variables into a simple, easy to understand, pair of numbers becoming misleading in usage. In compressing that information it does a good job, but people tend to forget that it's a lossy function and to concentrate on the CAT rating rather than details. There's a tendency for people to grasp the simple, easy to understand stuff and fool themselves that they know more than they do (e.g. acting as if knowing the CAT rating of a meter and the CAT rating of a DUT are sufficient to completely determine the safety of a particular test set up).
You can see a lot of that on here, with people arguing about the CAT ratings of meters when I'd be prepared to place a moderately substantial wager that no party to the discussion had read IEC 61010 for themselves.

It is not helped by the fact that the standards that actually define the CAT rating system are hard to find to reference, and hard or expensive to get hold of a personal copy of. Most essential standards, even if in theory belonging to the set of expensive "pay to play" standards, have a tendency to leak out and become accessible. If people need access to the information they find a way. It's telling that this hasn't happened with IEC 61010, suggesting that people are quite happy to stumble along with second hand summaries of what IEC 61010 has to say about CAT ratings rather than reading "the Bible" for themselves.

[McBryce]

The Thandar SC110 arrived this morning, didn't look too bad, battery door is missing, and the battery carrier had 4 C cells in it, looking the worse for age but no corrosion, so that's a bonus. Took a punt on it and removed said batteries, all were well and truly flat, just 1.7v, all 4 connected in series  . Connected it up to my bench supply and switched on, there is a beam but no sweep, I can move the spot sideways and up/down, but movement to the right is restricted to half way. Vertical amp is working OK when connected to the scopes test point and the beam is reasonably bright, so that's a relief, always a bit disconcerting when buying something that is not shown powered up.

So it's now time to get the manual out and dissect this puppy and look for signs of problems on the inside. Photos and more to follow in due course.

   

Great! Now you need the whole set! 

BAMA has the SM, but I found a better copy here with actually legible schizzmatics:

https://k1.spdns.de/Vintage/Sinclair/Other%20Inventions/Other%20Electronics%20Products/Thandar%20SC110A%20Oscilloscope%20Service.pdf   

It's too big to post here for posterity, but I did observe due diligence and eMailed Ed a copy so he can update BAMA.

Interesting... it appears Sinclair's MicroVision TV uses the same plate-deflection CRT:

http://lushprojects.com/blog/2015/07/thandar-sc110a/

mnem

I have a Sinclair branded DM350 (Thandar TM35). Still working well and in Cal.

McBryce.