Test Equipment Anonymous (TEA) group therapy thread

[med6753]

BTW, µ is altgr-m in other Unices such as Linux, not just bastardised BSDs such as macOS

https://www.opengroup.org/openbrand/certificates/1212p.pdf 

I've got to say, the ambiguity between the whole pF and uF scales on circuit diagrams has pissed me off for years, especially when you see someone specify obviously an electrolytic capacitor with "1000" so you have to reverse engineer what it's used for before you can determine if it's 1nF or 1mF 

Well, that's why a smart draftsman always has notes on his diagrams specifying exactly what his symbology means. 

[bd139]

Smart draftsman uses all the prefixes

[tggzzz]

Smart draftsman uses all the prefixes

And don't use ".".

[vk6zgo]

A few days ago I said I wasn't going to look at the faulty display board from the 5248M counter till I had fixed all the other problems, but playing spot the difference with the readout board from the 5245L and trying that one, I realised the difference is in the neon/photo resistor based decoder section (the board from the 5245L only displays 3,4 & 5). 


Noticing the corrosion on the tube socket I thought I would have a look inside the decoder block to see if it was in the same condition, maybe it needed cleaning to stop the random glow (from all the digits) from the number readout bulb.
How wrong I was, unfortunately damp has got inside the block & eaten away some of the traces on the photo-resistor plate and this plate is the main difference in this display board between the 5248 & the 5245 models.

Before & after cleaning with IPA,



Looks like I'm stuck with only 7 usable digits unless/until I can find a replacement. 

Nearly everyone blames the neons for faults with these display boards, but in this case it was the photo-resistor & decades of neglect in a damp shed.


David

It's not always from that, I remember having the same problem back in the 1970s!
We eventually just decided to "live with it!"

[mnementh]

No Comment

Can't think of a better use for a 123... 

mnem
"Beastly things... beastly..." C3P0 - Empire Strikes Back

[Robert763]

It's actually a very clever design Not only do the neon lamps turn on the LDRs thay act as switches / level detectors. Turning on a Neon in a series circuit clamps the voltage at that point and stops neons lower down the chain lighting. The LDRs have different areas giving different on resistances.

[med6753]

Making some progress with the trace drop out on the 7603N scope. See schematic.

Luckily it's not the HV that drops out. The HV Oscillator at Q764 and Q766 is happily going at 40.8kHz even when the trace goes bye-bye. The Z-Axis pulse at Point 1 and 2 on the Z-Axis board goes flat line. So that effective cuts off the CRT. So....gotta trace Point 1 back.

I'm glad I don't have to open up the HV cage. 

[Robert763]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc. 

[factory]

Looks like I'm stuck with only 7 usable digits unless/until I can find a replacement. 

Nearly everyone blames the neons for faults with these display boards, but in this case it was the photo-resistor & decades of neglect in a damp shed.


David

Hmm, would a plate from a lower decade from a 5245 work? At leat it will do 0-9.

I first need to have a look at the manuals to determine why the 5245L board only displayed three out of ten digits.

David

OK I think I've got a solution, just need to open another board to check what decoder plate it uses, then order some more.

The A18 high speed display boards for the standard 5245L & 5248M differ in the binary code from the A17 counter board.
In the 5245L the code is A to 12, B to 13, C to 14 & D to 15 on the A18 board.
In the 5248M the code is A to 15, B to 13, C to 14 & D to 12 on the A18 board.

Looking through four dead tree manuals I have, I've found a possible solution in the lower speed option 002/003 boards from a 5245L, these apparently use the same readout block (no part is given for the photoconductor plate in any manual) as those in the standard 5248M.

David

[Ero-Shan]

That's interesting. What does the photoresistor do in that assembly?

Brightness/intensity feedback for the neon tubes?

It's the decoder for converting the binary from those pairs of transistors to decimal for the number display bulb. I need to have a better look the paper 5248 & 5245 manuals to see why they needed to use a different decoder plate.

David

That was a congenial design, as they used the voltage difference between firing and sustained glowing of the neons to also implement a memory.

edit: Gah! BD and Robert beat me to it. I guess my Indian name is "never in time"

[med6753]

I hate intermittents. I traced the Z-Axis back to this logic interface board which interfaces to the TD-1085/U Time Base plug-in. For giggles I pulled and reseated the plug-in. With the plug-in pulled the CRT is cut off. Inserted the trace comes back. And now it's not failing. It's solid. Did I fix it? Maybe which is the frustrating part. My only choice right now is to leave it powered on and see what happens.

A TD-1085/U plug in is equivalent to a 7B53AN.

[med6753]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

[mnementh]

Ehhh... if it explodes when I explode, wasn't my car note.     Don't Google r/dragonsfuckingcars.

   Brain bleach.... getcher brain bleach right here... Only $10 a bottle...

mnem
Wifey sez it's fine with her; no diff from spanking it...

I woke up to this 

Well, I did try to be subtle at first; only alluding to r/D-Effing-C instead of smacking people in the face with it.  I should have known subtlety was wasted on this lot.   

mnem

[tggzzz]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Yup. I can't remember when I started doing that, which means it is a long time ago

[bd139]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

That's ok until you get a shitty Mauritron scan to work off that looks like a pepper mill exploded near it

[tggzzz]

I hate intermittents. I traced the Z-Axis back to this logic interface board which interfaces to the TD-1085/U Time Base plug-in. For giggles I pulled and reseated the plug-in. With the plug-in pulled the CRT is cut off. Inserted the trace comes back. And now it's not failing. It's solid. Did I fix it? Maybe which is the frustrating part. My only choice right now is to leave it powered on and see what happens.

DeOxit the connectors and, if there are any, transistors in sockets?

[tggzzz]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

That's ok until you get a shitty Mauritron scan to work off that looks like a pepper mill exploded near it

I started with blueprints which have the same problem.

[Cerebus]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

That's gonna be a hard thing to do, finding a 2200 ohm resistor that is still a 2200 ohm resistor at -455.71 degrees Fahrenheit.

[med6753]

I hate intermittents. I traced the Z-Axis back to this logic interface board which interfaces to the TD-1085/U Time Base plug-in. For giggles I pulled and reseated the plug-in. With the plug-in pulled the CRT is cut off. Inserted the trace comes back. And now it's not failing. It's solid. Did I fix it? Maybe which is the frustrating part. My only choice right now is to leave it powered on and see what happens.

DeOxit the connectors and, if there are any, transistors in sockets?

Yep, I plan on giving the plug-in a shot of deoxit. There are IC's in sockets on that interface board. Problem is....in order to get to them I'd have to pull the PSU.....again. 

It's still running. 

[med6753]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

That's gonna be a hard thing to do, finding a 2200 ohm resistor that is still a 2200 ohm resistor at -455.71 degrees Fahrenheit.

OK, start searching and let me know when you find one.   

That will keep you busy for a while. 

[mnementh]

That's okay... there's this sexy little red Mazda Miata down the street I been thinkin' aboot for a one-nighter...    r/D-Effing-C

You can't even FIT in a Miata. 

Like he said,"There's not mushroom inside!"

*rummages in back of closet for soggy ol' boot to lob OZ-ward; finds only a soggy ol' Fiat*

Meh.... not like it's good for anything else...

*Flies down to Bermuda; digs hole all the way through the earth*

*LOB!!!*

*Relaxes under a palm tree and sips a Mohito*

mnem

[Robert763]

Smart draftsman uses all the prefixes

And don't use ".".

Current gudance is use the multiplier letter as the decimal eg   0u1 4n7 2M2  0R1 etc.

Sorry, I'm old school. The decimal point is in play. Along with K = 1000. So a 2200 ohm resistor will be 2.2K.

 

No, thrice no. Upper case K is Kelvin  so 2.2K is very cold. 2k2 is OK. 

[cyclin_al]

I'm not sure if that is much worse than the Franglish or Deutschlisch like we used to encounter back in the day!

If already, then already: Denglish, pls! svp!

Ok "Denglish" ------------its just that "Deutschlich"sounded so deliciously "fake German"!

For a non-multilingual person, the German texts were a bit easier to sort of "reverse engineer" than the  French ones, paricularly if I had access to the original language text.

EEs being EEs & draughtsmen being draughtsmen, though, from time to time we were confronted by fairly sketchy symbols designated by non standard terms, like "Drossell" instead of "Induktor".
I was pretty sure that's what it was, but the only translation I could find referred to a type of bird!

The French seemed to delight in confusing me totally.
One favourite of  the company which made our gear was using the same designation for multiple devices without quoting which module each one was part of, so a series of "daisy chained" relays may have two or more RL1s.

It can get worse.  Have you tried translating from French to French?  Okay, it is probably more correctly French to Quebecois.  While the French may delight in confusing others, the Quebecois make a miserable attempt at establishing a distinct society.  Distinct, definitely; I have no idea where those words come from.  The Quebecois words appear to have no similarity whatsoever to French words in many cases, at least when it comes to bicycles and electronics.

Here in the Great White North, our term for Franglish is Franglais (francais-anglais), which rolls off the tongue pretty nicely

[mnementh]

...How wrong I was, unfortunately damp has got inside the block & eaten away some of the traces on the photo-resistor plate and this plate is the main difference in this display board between the 5248 & the 5245 models.

Before & after cleaning with IPA,         Looks like I'm stuck with only 7 usable digits unless/until I can find a replacement.     (SNIP)

David

Aww, man... that truly blows. Think there's any chance of resurrecting with a silverized conductive pen? I can't think of a better candidate to at least give it a try.

mnem
 

[cyclin_al]

That's an inductive resistor 

I use nF (and mF once in a while) what's wrong with mF?
Is it because people confuse m for mili- with the m at the begining of micro- used for μF?

I was educated with the Metric System in Canada which uses a standard set of prefixes in SI units (so why is Metric System = Systeme Internationale anyway?).
My understanding is the prefixes should be portable and common across the units.

For example, mm is milimetre, ml is mililitre.  Therefore mF should be miliFarad.
Similarly, um is micrometre.
Use of mm for micrometre would create a huge amount of confusion and error.  Likewise, we should not use mF for microFarad.

Prefixes I can recall from memory:
Mega (x10^6)
kilo (x1000)
Deca (x10)
deci (/10)
centi (/100)
mili (/1000)
micro (/1000000)
nano (/1000000000)
pico  (/1000000000000)

https://en.wikipedia.org/wiki/Metric_prefix
Darn, I should have remembered Giga, Tera, hecto & femto...