Test Equipment Anonymous (TEA) group therapy thread

[BU508A]

Shahriar introduced the other day a cheap battery driven spot welder.
Guess what?
Today a similar device showed up here.     

I've bought it for ca. 67 Euro at Amazon. It is a InLove-As-0532
(Really, who comes up with these stupid names all the time?)

Picture from Amazon:


I did a little teardown and spot welded two Nickel stripes.
The construction is a bit different than the one from Shahriar.

The front panel with all the connectors and knobs.


Overview, front- and backside of the PCB. Lots of vias. The two battery backs are connected in parallel.


The OLED display, backside and in use. This thing is able to throw out 460A with ease!


The copper tips and the high current connectors.


I did a little test with two Nickel stripes and here is the result. Back- and frontside.


I've isolated the area between the display and the screws of the battery packs with Kapton tape, because the display is flapping in the breeze and it could shorten the battery packs. Not a good thing imo. It is recommended to check first the construction of such a spot welder before the first use. Shariahr mentioned this as well in his video.

Thank you for watching.

[Cerebus]

I imagine many more are end of life, or no longer made now.

This is so for a lot of things. And I guess that chipageddon has made retiring legacy series easier..  Pity that it is a losing proposition, mostly, to buy NOS capacitors.

I went BOM'ing for the 10MHz LC filter Cerebus suggested upthread and 750nH is not readily available in through-hole, period. Lots of µrata SMD available for next to nothing, of course.  I assume I'll have to churn through a few more of those SMD exercise boards, bite the bullet, and actually teach myself SMD.

You can always fiddle with the parameters here: https://rf-tools.com/lc-filter/

Tell it that a minimum 1uH inductor is acceptable and it'll offer 110pF and 680pF for the capacitors.

I went for a 3rd order Bessel filter for no other reason that 99% of the time for measurement circuits a Bessel is the best choice (linear phase and all that), but you can go wild if you like. 6th order eliptic, no problem:



It'll export to LTSpice so you can even simulate it if you want.

[mnementh]

Awww, doody bombs. Frustion360 doesn't support my old MacPro since... well, before I got it. 

Guess I'll just have to glom up a spare disk and install Winblows on it... 

mnem
 

Currently nuking OSX Catalina for my UberCheeseGrater. Pray for me. 

mnem

[mnementh]

DISQUALIFIED ! 

The Fluke 87 is hardly a cheap bare bone meter like the 10/11/12 are ! 
the 87 s a very nice meter, good accuracy, high count/resolution, good features, and expensive.

I would love to add one to my collection (have 4 old Fluke DMMs in all), but here at least, the Fluke brand markup is too much. They aren't good enough value for money. That's why I prefer buying Metrix MX 53/54/56, way better value for money overall.

I can't justify spending 90 euros on an old Fluke 73 say, or 75 ot 77 even, when the same money can get me a MX54/C for example. It just does not compute at all... 
So the few Flukes I do have, are only with me because I was lucky enough to find them at price point that makes sense.
If I can find a nice 87V for a price I like, I would buy it. Well, not now of course, no money for TE atm....

Of the 10 Fluke DMM's in my stash the 87 is the only one I bought new in 1997. Yes, it wasn't cheap.

I've never regretted the money spent on FLUKE. EVER. I got my 87 when I was working for Philips while working my way through my first degree, before they were even available for sale. I paid for it out of 6 paychecks, and it was my go-to meter for 30 years. IMHO, that is unbeatable ROI.

mnem
There's a reason this emoji looks like a FLUKE 87. 

I also love my Flukes, that being said, if I was buying a new meter, it wouldn't be a Fluke, it would be another Brymen, the second only new DMM I have brought in my life.

Fortunately, they're made such that you can buy one decades old and still be reasonably certain it will still say BAMMM!

mnem
 

[mnementh]

mnem
See you all on the other side...

[srb1954]

While you have your A6902 opened up can you post some close up pictures, from various angles, of the shields around the toroidal transformers? I believe these shields were added to later models to reduce HF noise on the channels.

Unfortunately, my A6902A doesn't have these shields and is quite noisy on channel 2. I would like to fabricate and install suitable shields to see it that will reduce the noise levels but I have not been able to find any details on the physical shape of shields and how they are connected to the rest of the circuitry.

Thanks in advance.

[Carl_Smith]

Mouser operate in Europe https://eu.mouser.com/aboutus/
You might not get the same price as the USA though.....

But you do get free shipping from Mouser in the EU over a certain amount. Not the case here in USA. No free shipping regardless of amount.

This is my annual reminder that Digikey does do free shipping in the USA and Canada when you pay by check or money order:

https://www.eevblog.com/forum/chat/digi-key-has-changed-and-it-is-not-very-good/msg3273588/#msg3273588

Probably not super useful if you are buying a big BOM, but if you only need a few parts and you are not in a big hurry, it's killer.

I wonder if they would ship the 55 gallon drum of WD-40 for free. 
https://www.digikey.com/en/products/detail/wd-40/640292/14039489

[Zucca]

We're on Sweden's second largest island-in-lake, 82 km² size, and some 700 meters from the lake, on a small rocky hill, so no loop in the lake.
We've got a loop 150 metres straight down, OTOH. Geothermal is really nice. Clean (providing the electrick power is), efficient, low maintenance. 

Yes! Well done mansaxel! Bravo!
150 meter down trough rock are not cheap (I imagine), but worth every penny!

Here near me at least three of new house communities are being built right now.
No passive homes, no geothermal, no PV panels, nothing. Old school stuff just to sell and cash in.

This is so sad, home builders who uses 20 years old technologies are criminals at Putin level.
Imagine those families moving in, most of them unaware of what they will pay in bills in the future. Nuts.
So sad.

[Zucca]

Shahriar introduced the other day a cheap battery driven spot welder.
Guess what?

I regret not to buy this when I was living in Germany.

[Zucca]

Yebbut since you dodged the bullet on that bunk lot of micro/telescope objectives, even after you buy the baby-brother PZ-57s you'll still be $540 to the good... and you'll thank me every time you meet one of those Chinesium screws made of case-hardened cheese...

Not only I got the PZ-57, but if you post a PZ-56 I will buy it as well.

[tggzzz]

While you have your A6902 opened up can you post some close up pictures, from various angles, of the shields around the toroidal transformers? I believe these shields were added to later models to reduce HF noise on the channels.

Unfortunately, my A6902A doesn't have these shields and is quite noisy on channel 2. I would like to fabricate and install suitable shields to see it that will reduce the noise levels but I have not been able to find any details on the physical shape of shields and how they are connected to the rest of the circuitry.

Thanks in advance.

I had noticeable 30kHz SMPS noise on channel 2, and less on channel 1. I replaced C2360/2361/2560/2561 with some new 1000µF electrolytic capacitors. I replaced C1005/1019 4.7µF10V tant beads with 47µF 16V tant beads. The 30kHz is much reduced, even without the pre-amp tin box cover screening.

The main amp PSU is, by design, about 7V rather than the 5V on the schematic. The pre-amp PSU was about 7V, but I tweaked that to 5V and did the DC adjustments. Everything is now symmetrical around 0V, and the waveforms are cleaner. Remaining task is to reduce the peaking on fast input transitions.

[mnementh]

Oh dear... I do believe my arcane incantations may not have been perfectly iterated...   

mnem

[Neomys Sapiens]

ALS MENSCH ZU DOOF, ALS SCHWEIN ZU KLEINE OHREN!
(Too stupid for a human, the ears too small for a pig)

This is the only thing left for me to say about a contractor from a nordic country which shares a sizable length of border with the evil empire. When you see 7/8" transmission line brought into a shelter and then connected via a stack of an attenuator, a surge arrester and an adaptor directly to an N connector on a RF unit those people should not even be trusted to install a cast iron sewage line. Really.
Is basic mechanics like the lever advantage really beyond the grasp of such ogres?

[Neomys Sapiens]

Good luck with your cap hunting - component sourcing can be incredibly aggravating and soul sucking at the best of times; add in the current supply chain issues and it's a total nightmare!

Weekend just shoved two more jobs to my queue: Phone PBX died and wifes ironing went dead. The latter is a thermonukefuse with 240°C, the former some bulging crapacitors. Well, after more than 20years uptime those have approx 200.000hours. Found to my astonishment: The bulging one was the best (reasonable ESR at abt. 0.15 Ohms and still half the capacity) whereas some smaller ones are not even detected by the ESR70. So they all have to leave. Upon collecting them in the cart, some items went to unavailable between monday and tuesday, so I had to review my order
Ordered at Digikey 2022-03-15 11:19 and shipped at 14:07. Expected delivery tomorrow.
Order from "local" Reichelt 2022-03-15 11:26 has not even been processed yet...

I got burned last year at work with stuff going out of stock while the higher-ups hemmed and hawed over whether we would order and kit the parts or if they'd have the board house source and supply them. I had everything ready to go while they cogitated on this, and then when they decided that we'd get the parts the FPGA was just GONE.  Wound up getting the few we needed from one of those sketchy resellers for about 4x the cost and 8x the lead time (not to mention a few hours of looking for them) after all was said and done, but that one still bothers me.  Shit or get off the pot, dammit!   

I hope this crazy parts situation stabilizes soon, but the reality I see says don't hold your breath - my money's on it getting much worse before getting any better.
 

-Pat

Totally the same here. But they found some. And then they were offered a switching regulator chip which normally goes for 4.something€ for over 50.-! Oh the wailing and crying! 

[JamesH]

@mnementh I love a cheese grader Mac Pro, I have a MacPro4.1 in my garage that I upgraded to 8 cores {(and I think 32gb ram), what are your specs?}; I see your geforce card, wanted to do that for playing older games. What's your usage plan for the Mac Pro?

P.S. First post (minus those in the support sub-forum), love reading y'alls back and forth over the years. Had a lurker account that dave purged btw

[Brumby]

ALS MENSCH ZU DOOF, ALS SCHWEIN ZU KLEINE OHREN!
(Too stupid for a human, the ears too small for a pig)

This is the only thing left for me to say about a contractor from a nordic country which shares a sizable length of border with the evil empire. When you see 7/8" transmission line brought into a shelter and then connected via a stack of an attenuator, a surge arrester and an adaptor directly to an N connector on a RF unit those people should not even be trusted to install a cast iron sewage line. Really.
Is basic mechanics like the lever advantage really beyond the grasp of such ogres?

Just checking here...  You mean NO proper securing or strain relief ... at all?

[mnementh]

I think he's much more concerned aboot the leverage that huge piece of pipe has against a ~4mm brass straw on the N-connector without so much as a semi-rigid whip between the device and that lever.

I could hear him  cringing all the way over here... 

mnem
"Better thee than me..." ~grand-dad

[Martin Miranda]

it's been in storage since October 2021, time to power up and clean.
i never turned this on. since it might have a shorted tantalum or bad ac filter. so i'll slowly power up.

[Neomys Sapiens]

ALS MENSCH ZU DOOF, ALS SCHWEIN ZU KLEINE OHREN!
(Too stupid for a human, the ears too small for a pig)

This is the only thing left for me to say about a contractor from a nordic country which shares a sizable length of border with the evil empire. When you see 7/8" transmission line brought into a shelter and then connected via a stack of an attenuator, a surge arrester and an adaptor directly to an N connector on a RF unit those people should not even be trusted to install a cast iron sewage line. Really.
Is basic mechanics like the lever advantage really beyond the grasp of such ogres?

Just checking here...  You mean NO proper securing or strain relief ... at all?

single plastic cable tie more than 50 cm away, next in 1.5m

[mnementh]

For good or evil... I made it to the other side. Trying to decide whether the value of Catalina (the latest OSX) is worth the inherent security risk of running MacOS that has been "patched" by an out-of-channel 3rd party to work with this old box... I suppose if Frustion360 works with it, I can just not use it for anything that has money or important communications tied to it...

https://github.com/dosdude1/macos-catalina-patcher

http://dosdude1.com/catalina/

https://www.macrumors.com/how-to/install-macos-catalina-unsupported-mac/


mnem
*toddles off to ded*  

[cyclin_al]

Mouser operate in Europe https://eu.mouser.com/aboutus/
You might not get the same price as the USA though.....

But you do get free shipping from Mouser in the EU over a certain amount. Not the case here in USA. No free shipping regardless of amount.

This is my annual reminder that Digikey does do free shipping in the USA and Canada when you pay by check or money order:

https://www.eevblog.com/forum/chat/digi-key-has-changed-and-it-is-not-very-good/msg3273588/#msg3273588

Probably not super useful if you are buying a big BOM, but if you only need a few parts and you are not in a big hurry, it's killer.

I wonder if they would ship the 55 gallon drum of WD-40 for free. 
https://www.digikey.com/en/products/detail/wd-40/640292/14039489

It looks like it is not even sold by DK, and it looks like it is available only in the USA:

MARKETPLACE PRODUCT
Will ship in approximately 13 days by IndustrialSupplies.com
A separate shipping fee may apply.

How long would it even take to use that much of the stuff?

[srb1954]

I had noticeable 30kHz SMPS noise on channel 2, and less on channel 1. I replaced C2360/2361/2560/2561 with some new 1000µF electrolytic capacitors. I replaced C1005/1019 4.7µF10V tant beads with 47µF 16V tant beads. The 30kHz is much reduced, even without the pre-amp tin box cover screening.

The main amp PSU is, by design, about 7V rather than the 5V on the schematic. The pre-amp PSU was about 7V, but I tweaked that to 5V and did the DC adjustments. Everything is now symmetrical around 0V, and the waveforms are cleaner. Remaining task is to reduce the peaking on fast input transitions.

Thanks for the pictures.

It is not clear from these pictures whether the shield is grounded or connected to some other circuit common. Can you confirm if there is a electrical shield connection?

I opened up my A6902A to compare and found it is has a substantially different layout compared your unit, which I assume is an A6902B. In particular it seems to use linear supplies rather than the switching convertor in your unit hence the suggested capacitor changes would not apply to my unit.

I have downloaded the service manuals for the A6902 and A6902B from Tekwiki, which unfortunately doesn't have a service manual for the A6902A. Neither the A6902 nor the A6902B match the circuitry on my unit (S/No B010956) at all so it appears that this product has gone through at least 3 major design revisions in its life.

[mansaxel]

Fortunately, they're made such that you can buy one decades old and still be reasonably certain it will still say BAMMM!

6 of my 7 Flukes (8020,8022,8060,8060,10,27,123) are from last century and they all are in-spec, with margin. That company is very good at what they're doing. Simply put. And, they've understood what makes people buy their gear; they prioritise dependability.  What good does a magic resolution, 58 new features, and so on, if the thing you are going to use tells you lies now and then? Crap meters do that. Flukes don't. 
One can argue that my opinion was formed when there was two kinds of handheld DMM, Flukes and crap copies of them, so landscape is different; now one can get Gossen, could get [hp], there's Metrix, Yokogawa and so on. And people tell me both Brymen and Uni-T are useful. So, it's different.

Pro power amp maker QSC used a quite clever catchphrase in their advertising; "Boringly reliable". That's what I want.

[mansaxel]

Trying to decide whether the value of Catalina (the latest OSX) is worth the inherent security risk of running MacOS that has been "patched" by an out-of-channel 3rd party to work with this old box... I suppose if Frustion360 works with it, I can just not use it for anything that has money or important communications tied to it...

I think you'll be good. Having a supported OS (even if a bit sideloaded) is better than running on old code. If it's snappy enough, that is.

[Brumby]

Just checking here...  You mean NO proper securing or strain relief ... at all?

single plastic cable tie more than 50 cm away, next in 1.5m

Yeah, like that will hold up to much.

I've never worked with anything chunkier than RG11 and I used saddles for securing that stuff.  A couple of cable ties were used to keep it trained, but weren't used for primary fixture.