Test Equipment Anonymous (TEA) group therapy thread

[0culus]

Not gonna lie, those early iPods were awesome devices. They did one thing and did it very well. Pretty sure that seller is smoking something reeeeeally good though. 

[VK5RC]

I nearly choked on my coffee when I re-read the price, I initially misread the price as $200 USD on 1st skim read!

[med6753]

Just wait until some yo-yo offers up a 1st gen IPhone in original packaging. $20K USD won't even register in the bidding war. 

[tonyalbus]

Just wait until some yo-yo offers up a 1st gen IPhone in original packaging. $20K USD won't even register in the bidding war. 

interesting... i have one...

[vk6zgo]

Yeah!
It seems strange that we can all happily use decimal points with money, but are too stupid to realise when some circuit designations don't make sense!
It's the same mentality which has ginormous lengths of timber sold in mm instead of metres.

As someone else already pointed out, it's not uncommon for component values, or current measurements, in a circuit to cover a huge range of values. A capacitor microphone preamp might easily include 10G ohm resistors and 100 ohm resistors. We use money for things that we've got, at first sight, a good grasp on the general price that they ought to have (a car, a loaf of bread, and so on), we'd spot a crazy value much faster than we might in an unfamiliar circuit.

My comment was really pretty much "tongue in cheek"!

In my experience, the schematics which had been (horribly) photocopied were usually the ones that needed (& mostly used) the now preferred method, although with European stuff, it was often a "lucky dip" as to which system the original draughtsman used.

Strangely enough, it was almost always European gear that supplied cruddy schematics.
Australian, US, Japanese & British stuff usually supplied schematics ranging variously from excellent to reasonably good.

That said, there were notable exceptions------the workshop manual for one piece of TV test gear from a smallish UK company had the first couple of pages of schematics nicely & clearly done, but the last one, whilst it started OK at the left side, deteriorated into "chicken scratches" by the RHS.

It looked like the person doing the job left the company half way through the page, nobody else could understand the EEs original scribbly circuit, so they just reproduced that bit unclarified.

I used to love it, back in the day, when an EE would tack together a self supporting "spiderweb" of components, which would "work a treat".
The poor old Tech then had to make a permanent version on a PCB, which often had major problems with stray capacitance which were absent from the "spiderweb"!

[tggzzz]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

[tggzzz]

My comment was really pretty much "tongue in cheek"!

In my experience, the schematics which had been (horribly) photocopied were usually the ones that needed (& mostly used) the now preferred method, although with European stuff, it was often a "lucky dip" as to which system the original draughtsman used.

I can't afford the ArtekMedia scans for all my equipment, so I have to make do with blobby (both +ve and -ve blobs) scans. Don't get me started on the available Solartron scans

I used to love it, back in the day, when an EE would tack together a self supporting "spiderweb" of components, which would "work a treat".
The poor old Tech then had to make a permanent version on a PCB, which often had major problems with stray capacitance which were absent from the "spiderweb"!

I saw one rats nest RF amplifier where the prototype worked but they couldn't reliably replicate it. Solution: dip the prototype 0.5mm deep in wax to define the positions, make a cast, and tell the techs to align the components with the peaks on the casts. (Where's the emoticon for "run away screaming").

No doubt subsequent generations of those perps were employed as software system installers.

[med6753]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

 

[med6753]

Just wait until some yo-yo offers up a 1st gen IPhone in original packaging. $20K USD won't even register in the bidding war. 

Oh shit...I misused UC K again. 

[AVGresponding]

Electrocuted means killed by means of electric shock. You're wearing this in the coffin?

[AVGresponding]

Oh, it is for sure a silver-based deposit; one of the first reliable methods developed for electroplating plastics and ceramic. I've run into this construction method many times; very popular in remote controls from the 80s, along with printed resistors. I was thinking maybe mask off with Kapton tape to make the traces...?

mnem
Time for a "Hail Mary"...!

I've had a couple fine reworks to do and seem to remember masking adjacent tracks wasn't the best solution removing mask didn't leave a clean cut and disrupted the added layer.
What worked best for me was removing the tip from the pen (clockwise unscrew for the CircuitWorks pens) and dipping in a sewing needle tip, move fast and repeat regularly.

Yeah, I've done similar with resist pens back in the day. Maybe something like these: https://www.amazon.com/AIEX-Miniature-Painting-Brushes-Watercolor/dp/B07PJ5GMX7/

with 000 size, or even a better set with 00000 brushes in it.

mnem
 

This is how bad it was after cleaning, I think if I had a go at trying to paint that it would end up an absolute dog's dinner. It would also be very difficult trying to find out where they need to connect under the photo-resistive material.


I think the seal has helped trap if any moisture that got underneath, picture below is of one the 5245L boards.


I opened up one of the six identical boards from the 5248M, which seems to have no corrosion. 
The decoder plate is the same as used in the faulty board, I've moved it to the high speed board. Sphere have some of the lower speed boards of this type and I've ordered some.


For completeness here is one of the display decoder plates from the standard 5243L, note the difference in layout of the traces & photo-resistor material.


David

I believe the picture you describe as being from the 5243 is actually a cropped version of the 5245 board picture.

Post-editing mixup?

[tggzzz]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

So, you also measure time in units of conductance (S)?

K isn't a UK measure of temperature, it is international, and the only way of referring to temperature above absolute zero.

Frequently "K" is used to mean 1024.

And two wrongs don't make a right!

Would you think it acceptable for a draughtsman to indicate that "m" means 1000000 on his drawing? Or to use multipliers of lakh (100000) and crore (10000000)?

Fundamentally the purpose of a document is to record information so that it can be used by other people. Anything getting in the way of that is to be deprecated.

[bd139]

I just tripped over this while looking for inserts for my iPod dock...   eBay auction: #182909336044

mnem
 

Got one of them somewhere I bought new. It’s knackered though.

[Robert763]

Electrocuted means killed by means of electric shock. You're wearing this in the coffin?

That's a pet peeve of mine. Unfortunatly misuse particuarly on-line has normallised electrocution to mean electric shock, not death by electricity. Seems to have started in the USA. Then again I'm a pedantic sod.

[med6753]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

So, you also measure time in units of conductance (S)?

K isn't a UK measure of temperature, it is international, and the only way of referring to temperature above absolute zero.

Frequently "K" is used to mean 1024.

And two wrongs don't make a right!

Would you think it acceptable for a draughtsman to indicate that "m" means 1000000 on his drawing? Or to use multipliers of lakh (100000) and crore (10000000)?

Fundamentally the purpose of a document is to record information so that it can be used by other people. Anything getting in the way of that is to be deprecated.

This is getting ridiculous. Your arguments and examples are irrelevant. The fact remains it was done on just about every American schematic you care to pull up. Whether it's still done that way I can't say. Perhaps we now "tow the line" and adhere to some accepted international standard. And basically you've indicted every American draftsman as incompetent. And as far as I'm concerned for my own use I will continue to use it.

And since we're tossing arrows back and forth across the pond riddle me this. How come a vacuum tube, 12AX7 for example, developed by RCA in 1947 is suddenly an ECC83 in Europe? It's the same tube. Why different naming convention for a tube that wasn't developed in Europe? Should it not carry the same designation to avoid confusion? In reality do I really care? Nope. Does it bother me? Nope. Is it WRONG? Absolutely.           

[med6753]

Electrocuted means killed by means of electric shock. You're wearing this in the coffin?

That's a pet peeve of mine. Unfortunatly misuse particuarly on-line has normallised electrocution to mean electric shock, not death by electricity. Seems to have started in the USA. Then again I'm a pedntic sod.

Is this blame America for everything week? I seem to have missed the memo. 

[tautech]

And since we're tossing arrows back and forth across the pond riddle me this. How come a vacuum tube, 12AX7 for example, developed by RCA in 1947 is suddenly an ECC83 in Europe? It's the same tube. Why different naming convention for a tube that wasn't developed in Europe? Should it not carry the same designation to avoid confusion? In reality do I really care? Nope. Does it bother me? Nope. Is it WRONG? Absolutely.         

Yep, Dads old RCA valve book didn't have any E****** valves in it, not a bloody one !
Only 5***, 6**** and 12****.

Later I got a Telefunken valve book...... 

[Brumby]

Perhaps we now "tow toe the line" .....

FTFY





(Sorry.)

[Specmaster]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

 

1000 times this, it is what I was taught at college and has been printed in every text book I have read. I really cannot understand why people don't know what the letters stand for, it is international standards and if they really cannot understand what k, M, p, m, n, G etc mean then bloody well google it, 5.7M to me says it all, but 5M7 makes me think that some silly arse has mistyped it 

[bd139]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

So, you also measure time in units of conductance (S)?

K isn't a UK measure of temperature, it is international, and the only way of referring to temperature above absolute zero.

Frequently "K" is used to mean 1024.

And two wrongs don't make a right!

Would you think it acceptable for a draughtsman to indicate that "m" means 1000000 on his drawing? Or to use multipliers of lakh (100000) and crore (10000000)?

Fundamentally the purpose of a document is to record information so that it can be used by other people. Anything getting in the way of that is to be deprecated.

This is getting ridiculous. Your arguments and examples are irrelevant. The fact remains it was done on just about every American schematic you care to pull up. Whether it's still done that way I can't say. Perhaps we now "tow the line" and adhere to some accepted international standard. And basically you've indicted every American draftsman as incompetent. And as far as I'm concerned for my own use I will continue to use it.

And since we're tossing arrows back and forth across the pond riddle me this. How come a vacuum tube, 12AX7 for example, developed by RCA in 1947 is suddenly an ECC83 in Europe? It's the same tube. Why different naming convention for a tube that wasn't developed in Europe? Should it not carry the same designation to avoid confusion? In reality do I really care? Nope. Does it bother me? Nope. Is it WRONG? Absolutely.         

Ah this one is a particularly large shit show. The 12AX7 and ECC83 designations don't actually relate to a specification believe it or not, only the heater configuration, form and socket for the device. The actual tube characteristics were all over the shit. They introduced whole new systems (JEDEC - 2N3904 etc and Pro-Electron - BC107) which were supposed to ratify this further by proving standard specifications. But again they fucked it up and not all parts are substitutable or equal. Here we decided this wasn't good enough and provided another system (common valve - CV7423 etc) which was used by telecoms and military which did have hard specifications. But that was abandoned as well. And of course then there were the manufacturers who came up with their own systems either based on NSN (Tektronix) or HP's internal numbering which was sort of NSN but not. All those devices have their own mostly undocumented hard specifications with a list of "mostly suitable but probably selected" substitutes.

So the reason it's wrong is humans can't organise shit. Guess who had to write the asset management software to manage this inventory and supplier shit show once .

That is however an entirely different problem domain to unit ambiguity and the only way to avoid ambiguity is being concise and explicit about units and scalar values. A fine example of what happens when this is fucked up is right here: https://en.wikipedia.org/wiki/Mars_Climate_Orbiter

"The primary cause of this discrepancy was that one piece of ground software supplied by Lockheed Martin produced results in a United States customary unit, contrary to its Software Interface Specification (SIS), while a second system, supplied by NASA, expected those results to be in SI units, in accordance with the SIS."

This is mostly proof that things need to be explicit and what happens when you make assumptions or ignore the specifications. Also when you have poor SIT process. American draughtsmen, and engineers clearly based on the above situation, run on assumptions, defacto undocumented standards and luck (especially Heathkit with the latter  ).

[med6753]

Oh yes....I understand there are cases where a 12AX7 or ECC83 isn't exactly a 12AX7/ECC83 to another and then you got someone else with a different idea of what it should be. It's a freaking mess.

Yep, that Mars Climate Orbiter was an absolute FUBAR on Lockheed-Martin's part. Maybe that's why you Brits can't crack the F-35's OS. 

[shakalnokturn]

Whatever you like for your own notes, mine are far from perfect, as long as you can make sense of yourself later it does the job.
When working with other people in industry, for once and at last there's something normalized and unambiguous when used correctly that's S.I. units, it seems a f'ing waste to not use it.

Although born in the UK I've only ever used S.I. (maybe with the exception of SMD passives footprint dimensions and other PCB layout habits), moving from UK to France was enough of a headache just for the "." vs "," and confusing ways of writing "1" and "7" between the two countries.

[tggzzz]

Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

Why not "k=1000"? I can think of places in a PSU where you might have both "M" and "m". (Bleed resistors or startup circuits, current sensing)

If you are going to use non-standard units, why not go the whole hog? For resistance you could use a "Siemens mercury unit", "Ohmad" , "Digney", "Breguet", "Swiss", "Matthiessen", "Varley", "German mile", "Abohm", "Statohm". For capacitance, Jars is an obvious alternative. Etc.

I am simply copying what apparently has been a standard here in the U.S. which for some reason you guys in Europe get all pissy and whiny whenever I mention it. I looked at schematics from Tek, HP, Fluke, Heath, etc and EVERYONE expresses UC K as 1000. The latest schematics I have dated in 1990's for the Fluke 87 have resistors expressed as, for example, 2.2K. Now I understand and accept that UC K also is for Kelvin. But over here it also stood for multiplier 1000. Right, wrong, or indifferent that's the way it was. I can't tell you if it's still used that way or not because we can't get schematics anymore. And as I keep mentioning...any draftsman worth his salt will have notes indicating what the specific symbology means. So I ask you...if that's done and it's understood what's the big fucking deal?   

 

1000 times this, it is what I was taught at college and has been printed in every text book I have read. I really cannot understand why people don't know what the letters stand for, it is international standards and if they really cannot understand what k, M, p, m, n, G etc mean then bloody well google it, 5.7M to me says it all, but 5M7 makes me think that some silly arse has mistyped it 

Yes, but then there are schematics which look like 5 7M or 5:7M or 5..7M etc due to crap reproduction.

[bd139]

Yep. Really the least ambiguous is to remove the decimal so a 5.7M resistor would be 5700kΩ. This is done a lot in E48 and above resistors so instead of 1.21kΩ you end up with 1210Ω. This is what was prevalent in the stuff I saw in the defence sector. And in most of the places they didn't mark the value on the schematic, only in the BOM with the NSN part, tolerance, power, voltage, temperature coefficient, supplier code etc.

[Cerebus]

That's why it's important for the draftsman to have good notes on his schematics which specify what parameters are used. Here's an example of a schematic I drew up for my own use. The notes specify for example resistor parameters and specifically that "K" means 1000.

A mathematician would call that "rigour", and it's a very desirable property. Even though you've used the wrong "K", so that we initially think you mean Kelvin, you've annotated it so that we can divine your actual intent.

I have a pet hate with Electronics books, and that's poor rigour the moment they get anywhere near Mathematics. I've got a book on transformers et al. that you have to keep referring to the cheat sheet inside the front (not easy on a pdf) because they completely fail to use any reiteration of what symbol they are using for what anywhere the the piles of now impenetrable equations. A competent Mathematician will always bracket their equations with a "Given <list of symbols and their meanings>" and "where <list of symbols and their meanings>" set of rigorous expalnation of what they are manipulating.