Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

if you look at the HP service manuals, they don't tend to assume the meter impedance anywhere and the test points and voltage measurements are never at high impedance points without large warnings about it.

It's because they expect you to use a 3458A to check PSU voltages. (true story)

Edit: And before that, they assumed a 410b or sumtha'.

Dunno about the "b", but my 410C has a 100 M input impedance on most DC ranges.

I used a lot of AVOs over the years, but only ever saw one which had been smashed completely, as "throw the meter" wasn't a popular game back then!

I've seen a few DMMs which had gone to DMM heaven, although they still looked pristine on the outside.
The first UNI-Ts I used started to give weird resistance readings long before the battery alarm appeared.

Even my dear old Fluke 77 can get confused by a pulsed waveform when it was expecting smooth DC.

My Mum-in-Law's TV had a +150v rail supplied from a rectified overwind on the Horizontal Output transformer.
The filter cap had died, but the Fluke saw the resultant crud as a 108v DC voltage---a bit low, but not likely to cause the observed fault.
A 'scope told a different story, altogether!

In such situations you should practice “know thy circuit” first. Start with AC volts on your DMM then assume that is centred around the DC reading. That’s good enough to assert that the filter cap was not functional. Also the min/max reading on more complex DMMs is good for this.

I’ve had a couple of fucked DMMs but quite frankly the user would have been dead if it was an Avo.

What's even nicer is a modern DMM that displays both at the same time, as long as it does so reasonably accurately... one of the reasons I'll never go back to my 87s, and why you can have my 189 when you pry it from my cold, lifeless paws... 

mnem
I will beat you to death with my USMC 27 if you even touch my 189... and you already know where the probulator's goin'...

[mnementh]

I bet it was the much more rugged later design which the Fluke guy chucked across the room!

I was told the anecdote ~1980.

Nawww... it wasn't him said your tale was about a Fluke... it was me, following up with my own personal experience at Uni.

That would've been '90s.

mnem
I suddenly feel very, very old... 

[mnementh]

On Fluke ruggedness, I’ve seen a lot of totalled Fluke 25’s at hamfests. YMMV on assigning responsibility there 

Yeah, well some guys can break a fuckin' anvil... 

mnemories:
*Old man Belmore puts a lit M80 down on the frame of a truck I'm welding on*

"Ya better run!" he quips with a impish smile, then turns on his heel and saunters off...

[mnementh]

More local CL finds.

https://newjersey.craigslist.org/ele/d/sparta-tektronix-mhz-oscilloscope/7510713135.html

That 2235 looks to be in good shape and reasonable price. About 1.5 hours away. Very tempting. BD.....does the 2235 have the trouble prone switcher PSU? Also, if I need a vintage transistor I know where to go. 

https://newyork.craigslist.org/que/ele/d/ridgewood-oscilloscope/7519309169.html

My first scope. Actually, was my Father's. When I left home to strike out on my own my younger brother got it. The seller is delusional with that $100 USD price. Not interested.

I wouldn’t touch another damn 2235 again. I was a nervous wreck after blowing MOSFETs on the preregulstor on that asshat.

https://www.eevblog.com/forum/testgear/tektronix-2235-repair-thread/

After reading your shit show with that 2235 it's definitely giving me 2nd thoughts. I'll mull it over during the weekend. Hopefully someone buys it by then or it just might be road trip and a glutton for punishment.   

As long as it's not a 2230, I'm sure you'll be able to tame that wicked bitch. The 2230 takes the 2235 design and adds a bunch of unobtanium failure-prone parts loaded onto a whole digital processing board with maybe just about enough smarts to outwith a ant.

THAT is the Tek that's a red-headed Smurfette. Even the 246xx is a joy to overhaul in comparison.

mnem
 

[bd139]

On Fluke ruggedness, I’ve seen a lot of totalled Fluke 25’s at hamfests. YMMV on assigning responsibility there 

Totalled electrically, or totalled mechanically? The former is possible for any of us on a bad day, the latter would require such a level of creative incompetence that I don't think I want to risk being within 300m of someone capable of doing so.

Both!

I nearly bought one at the last hamfest to prove it 

[McBryce]

My favourite "pointless antique mini meter" is the Pifco All in One. They are just a work of art. They are tiny (65mm diameter) and look like a mini alarm clock / pocket watch.

I always think that they look like a model of a naval mine, with all those 'spikes' sticking out.

Well on the "chances of killing you scale" they are probably pretty close.

McBryce.

[mnementh]

Re AVO weird battery requirement - on my to do list:

Mikeselectricalstuff coin battery mod

Ah, a nylock so they don't become loose by themselves...

They do this, but it is not cheap.

https://www.ebay.de/itm/265531737706

LR44 inside sleeving from the $2 shop is the simplest fastest fix for the now nearly unobtainium 15V cell.

The official Ever Ready BLR121 is a stick of 10 LR54s in a plastic case. The LR54 is quite thin I don't think 10 LR44 would fit in a single stack. I had this slightly kanky one in a NOS bag. Fluke says 7.4 V

Edit: BU508 got it right independently. The BLR121 does have two contact buttons that are 2.1 mm high adding 4.2 mm to the total stack giving 24.7 mm.

Seems to me like an ideal project to apply 3DP to... 

mnem
 

[mansaxel]

Seems to me like an ideal project to apply 3DP to... 

Which is what you'll get when you buy some "for Avo 8" battery replacements on Ebay. It works, I'm not complaining, not too loudly at least.  I got the high ohms ranges back, which is nice.

[mnementh]

There was plenty of smaller, just as capable meters specifically designed for portability such as the excellent TMK500 or the AVO minor for instance, the AVO model your referring to was designed as a lab type instrument.

The TMK was a bit fragile, & the "Minor" was, as I commented earlier, regarded as a bit of a "toy". In practice, AVO 8s were used extensively in the field.

Yes, well... what TE manufacturer doesn't like a customer base with a built-in high rate of turnover...? 

mnem
tzzzzt.

[Specmaster]

On Fluke ruggedness, I’ve seen a lot of totalled Fluke 25’s at hamfests. YMMV on assigning responsibility there 

Totalled electrically, or totalled mechanically? The former is possible for any of us on a bad day, the latter would require such a level of creative incompetence that I don't think I want to risk being within 300m of someone capable of doing so.

Both!

I nearly bought one at the last hamfest to prove it 

Maybe we could have rebuilt it from parts?

[vk6zgo]

In such situations you should practice “know thy circuit” first. Start with AC volts on your DMM then assume that is centred around the DC reading. That’s good enough to assert that the filter cap was not functional. Also the min/max reading on more complex DMMs is good for this.

Ohh, I "knew my circuit" well enough, but at work, my instrument of choice was an Oscilloscope.
I didn't have one at home, so had to make do with the Fluke 77.

I did check by trying it on ACV, & got a reading of zero, but what I didn't know then, was that those very early 77s only worked up to 1kHz on that range, & then "hit a cliff".
(I still have the original booklet that came with the meter, & checked that my figures were correct, before posting)

I had assumed that it would read ACV OK at 15kHz, & expected a reading in line with your suggested one.
I guess one lesson to be learnt there, was to read the booklet!

I'm glad I still had the booklet---Googling brings up a lot about the later "versions", which are pretty much new designs, rather than refinements of the original.

On Ma-in-Law's TV, I borrowed an old BWD single beam 10MHz 'scope from work, & that revealed the true state of affairs.

I’ve had a couple of fucked DMMs but quite frankly the user would have been dead if it was an Avo.

What had happened to them?

[bd139]

On Fluke ruggedness, I’ve seen a lot of totalled Fluke 25’s at hamfests. YMMV on assigning responsibility there 

Totalled electrically, or totalled mechanically? The former is possible for any of us on a bad day, the latter would require such a level of creative incompetence that I don't think I want to risk being within 300m of someone capable of doing so.

Both!

I nearly bought one at the last hamfest to prove it 

Maybe we could have rebuilt it from parts?

I think a coup de grâce was more appropriate for that one 

[vk6zgo]

There was plenty of smaller, just as capable meters specifically designed for portability such as the excellent TMK500 or the AVO minor for instance, the AVO model your referring to was designed as a lab type instrument.

The TMK was a bit fragile, & the "Minor" was, as I commented earlier, regarded as a bit of a "toy". In practice, AVO 8s were used extensively in the field.

Yes, well... what TE manufacturer doesn't like a customer base with a built-in high rate of turnover...? 

mnem
tzzzzt.

In practice, the things just hung in there for decades---open one up, & they were built like a tank! (I'm talking about the real "point to point" wired ones, not the later ones with "fancy pants" PCBs).

[bd139]

In such situations you should practice “know thy circuit” first. Start with AC volts on your DMM then assume that is centred around the DC reading. That’s good enough to assert that the filter cap was not functional. Also the min/max reading on more complex DMMs is good for this.

Ohh, I "knew my circuit" well enough, but at work, my instrument of choice was an Oscilloscope.
I didn't have one at home, so had to make do with the Fluke 77.

I did check by trying it on ACV, & got a reading of zero, but what I didn't know then, was that those very early 77s only worked up to 1kHz on that range, & then "hit a cliff".
(I still have the original booklet that came with the meter, & checked that my figures were correct, before posting)

I had assumed that it would read ACV OK at 15kHz, & expected a reading in line with your suggested one.
I guess one lesson to be learnt there, was to read the booklet!

I'm glad I still had the booklet---Googling brings up a lot about the later "versions", which are pretty much new designs, rather than refinements of the original.

On Ma-in-Law's TV, I borrowed an old BWD single beam 10MHz 'scope from work, & that revealed the true state of affairs.

Ah yes. That's the one before you have to know your circuit. Know your tools

I’ve had a couple of fucked DMMs but quite frankly the user would have been dead if it was an Avo.

What had happened to them?

Well they might have died. Both of these came from house clearance auctions 

Well this is shocking to post here. Here's the aforementioned Fluke 25 as received. The HRC fuse was bypassed and soldered into the fuse holder which had at least one of the clamps blown off it...



I don't have a picture of the rotary switch but the bottom layer rotating contact was warped and the switch was melted.

And then there's this poor bugger. Notice the theme. Check the HRC fuse. There was a nice arc on the bottom of the board. Note the voltage reading when the inputs were shorted 



BOTH meters were completely restored to nearly new condition.

I really wish people would get the idea that if the fuse goes, it may have gone for a reason so you might want to think first 

[Specmaster]

Those 2 HP calculators have arrived, well-packed, delivered by Evri.

It seems that the 17BII, on the right can be switched in and out of the RPN mode when required manually, need to read the manual later for more info, but now its boy dropping off at work time and a spot of shopping, in this stupid heat, I must be mad.

[bd139]

Welcome to the dark side 

[Squarewave]

Those 2 HP calculators have arrived, well-packed, delivered by Evri.

It seems that the 17BII, on the right can be switched in and out of the RPN mode when required manually, need to read the manual later for more info, but now its boy dropping off at work time and a spot of shopping, in this stupid heat, I must be mad.

Nothing like a bit of HP. I've seen your calculators with my HP laptop.

Earlier today I found my HP voltmeters, forget the model number, but one uses a diode detector probe for AC and the other is a 6.5 digit huge bench top thing.

I also like HP sauce.

[Zucca]

I will have trouble to fall asleep tonight, do not post those pictures anymore.

[mnementh]

Pictures like that keep Darwin's ghost happy. 

mnem
Darwin was an optimist.

[BU508A]

Welcome to the dark side 

We have "="-keys? 

[ch_scr]

Welcome to the dark side 

We have "="-keys? 

We have calculators with "natural display"    - So you can focus on the task at hand & don't have to translate "to" and "from" calculator

[Zucca]

This is becoming a PG18 thread. Stop with those disturbing pictures....
That natural display is against nature.

[tggzzz]

Welcome to the dark side 

We have "="-keys? 

We have calculators with "natural display"    - So you can focus on the task at hand & don't have to translate "to" and "from" calculator

"Natural" display is relatively easy. How unnatural is the input and editing For anything remotely close to that complexity, I'd use a computer with a keyboard. A calculator or even a fondleslab is no longer the appropriate tool.

"1+2*3=9", for many values of "calculator".

[nixiefreqq]

Those 2 HP calculators have arrived, well-packed, delivered by Evri.

It seems that the 17BII, on the right can be switched in and out of the RPN mode when required manually, need to read the manual later for more info, but now its boy dropping off at work time and a spot of shopping, in this stupid heat, I must be mad.

will confess that if those were in the calculator tray at the thrift store i'da bought them.

on an unrelated topic.......finding solder blobs and jumpers on cartridge fuses........WTF??? 

[Robert763]

Just a slight warning for whoever has to deal with the soviet transistors(2G302 in the attached picture); it came out as CADMIUM COATED thru the mazes of my memories.
If anybody can confirm/deny my (almost)long forgotten memories, I(and the future owner) would be really grateful.

I've no idea and you did say "slight warning", but is it that big a deal? Cadmium coated nuts and bolts were popular until a few years back, and its use is now restricted, but they may be come across in old equipment. Welding cadmium coated steel is a different matter. I've got a few yellowish metal canned transistors on old boards. It would certainly pay to wash your hands after handling them.

Something I have across and is extremely dangerous, is beryllia in insulators. It's probably OK as long as you don't break it up. There are usually warnings about it. There are PCBs in some capacitors and transformers. There are fuseholders with asbestos. There are also mercury filled switches.

Goldmine will sell you both in one package
https://www.goldmine-elec-products.com/prodinfo.asp?number=G26544