Test Equipment Anonymous (TEA) group therapy thread

[Brumby]

I hope i didn't screw it.

Rotating sounds like a screwing motion to me....

[neo]

I hope i didn't screw it.

Rotating sounds like a screwing motion to me....

 
Not quite what i meant, excellent joke though.

[beanflying]

Clearly the fitter of this pommie plug wired Landrovers before working for Racal 

Uber crusty in places may the smoke stay in 

[beanflying]

So it will be a work in progress it seems but some of it is fine

https://youtu.be/vBVmMHhh-Dw

[URI]

Been programming python for 20 years.

I haven't programmed the last 20 years at all. Learned programming Borland Pascal at school (in the 11th -13th class for the diploma from German secondary school qualifying for university admission or matriculation, short: Abitur) and again used some variant of free Pascal at basic programming courses at university.
After that: No programming at all. No C, C++, Java, Hascal, Perl,.. 
Ok, I edited config-files, configured Linux kernels and wrote some shell-skripts locally to make life easier by automating some things concerning my Linux box. But I wouldn't call that programming. 

I think my head would explode if I tried adding Python to it so many programming languages already being forgotten in it now 

Not exactly the same for me but I fear running into similar problems, adding Python to my brain where all the place feels already occupied by other things I stuffed in there over the years.
Hopefully I will find some space left otherwise something will have to go, I guess..     

[beanflying]

There already resides residual Apple and Q basic, Pascal, Fortran, 6800 and 68000 assembler hex codes, PHP, Abominated java hacking and reasonable HTML and the current C++/duino 

Also don't know much about Nixies but I reckon I might have found the issue with the RH digit  18k off a 200v rail might bump them all to 22k and heatsinks... 

[bitseeker]

Well, that looks creative. Glad it was just some resistors.

[beanflying]

It gets better  Time for a little re engineering I reckon.

[bitseeker]

Woah, what is up with that?

[tggzzz]

Clearly the fitter of this pommie plug wired Landrovers before working for Racal 

My Series II Land Rover had (very comfortable) seats and rear lights from Minis, and the fuel gauge calibrated in roentgens/hour. I replace the wiring as and when the insulation melted.

It didn't have seat belts, but that didn't matter since everybody scattered from in front of it. There are advantages to having big, noisy, battered cars.

[beanflying]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

[bd139]

Is that racal? Doesn’t surprise me if it is.

[Specmaster]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

Those rounded end resistors are apparently notorious for being unreliable and ought to be always suspect number 1 in checks on any piece of gear that uses them and if possible replaced with the normal square ended ones. 

[tggzzz]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

Carbon compisition resisitors, which I presume those are, have two relevant characteristics compared with metal film resistors. CC resistors tend to drift high, and they are relatively tolerant of surges.

[bd139]

Carbon composition resistors should be reserved for selling to audiofools

Things that bugger up carbon composition resistors: vibration, applying voltage, heat, moisture, age, moon phase, looking at the stripes too long.

Surges; that's what those nice hybrid resistors are for these days.

[Specmaster]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

Carbon compisition resisitors, which I presume those are, have two relevant characteristics compared with metal film resistors. CC resistors tend to drift high, and they are relatively tolerant of surges.

Well these ones clearly have failed and those types are always high on my list of suspects when things go wrong and replacing these with their equivalent ones in square edge or metal film types is preferable, as recommended by Mr Carlson,

Carbon composition resistors should be reserved for selling to audiofools

Things that bugger up carbon composition resistors: vibration, applying voltage, heat, moisture, age, moon phase, looking at the stripes too long.

Surges; that's what those nice hybrid resistors are for these days.

Quite correct. 

[tggzzz]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

Carbon compisition resisitors, which I presume those are, have two relevant characteristics compared with metal film resistors. CC resistors tend to drift high, and they are relatively tolerant of surges.

Well these ones clearly have failed

Yup, they have drifted high.

and those types are always high on my list of suspects when things go wrong and replacing these with their equivalent ones in square edge or metal film types is preferable, as recommended by Mr Carlson,

Sometimes it pays to be careful, e.g. in the HT sections of CRT scopes and/or custom inverters.

[bd139]

Just a note. Vishay do some nice glazed metal ones (VR series http://www.vishay.com/docs/28907/vr25vr37vr68.pdf ). I've replaced quite a few CC units with them in HT circuits and they are wonderful replacements if you need 100k+. Otherwise the Vishay MRS25 and MBB0207/MBE0414 are nice. All available in low quantities via Farnell/RS as well.

I can't think of a single place where I would replace a vintage passive with a vintage passive. They're all pretty shit!

[tggzzz]

Just a note. Vishay do some nice glazed metal ones (VR series http://www.vishay.com/docs/28907/vr25vr37vr68.pdf ). I've replaced quite a few CC units with them in HT circuits and they are wonderful replacements if you need 100k+. Otherwise the Vishay MRS25 and MBB0207/MBE0414 are nice. All available in low quantities via Farnell/RS as well.

I can't think of a single place where I would replace a vintage passive with a vintage passive. They're all pretty shit!

I don't disagree, and thanks for the specific pointers.

I should have made it clearer that I was thinking of replacing a CC resistor with whatever metal film resistor that you happened to have in stock. I have a lot of the latter since someone donated ~110 different values of 1000pcs 1% 50ppm resistors to the local hackpace. I've got about 50 of every value; I doubt the other 'spacers will ever use up the rest!

[bd139]

Nice. I could do with a set like that. Very expensive though. £300+ for a proper development kit. Bought a whole book of cheap Royal Ohm resistors for development. Unfortunately I run a "swept bench" i.e. throw components at a design and then sweep them into a bag when done. So I'm already running out of loads of values.

Decided next time to just buy Vishay MRS25's on demand and spreadsheet it properly. And you know what, check the sodding back order lead on the things https://uk.rs-online.com/web/p/through-hole-fixed-resistors/6833165/

[Specmaster]

Just a note. Vishay do some nice glazed metal ones (VR series http://www.vishay.com/docs/28907/vr25vr37vr68.pdf ). I've replaced quite a few CC units with them in HT circuits and they are wonderful replacements if you need 100k+. Otherwise the Vishay MRS25 and MBB0207/MBE0414 are nice. All available in low quantities via Farnell/RS as well.

I can't think of a single place where I would replace a vintage passive with a vintage passive. They're all pretty shit!

I don't disagree, and thanks for the specific pointers.

I should have made it clearer that I was thinking of replacing a CC resistor with whatever metal film resistor that you happened to have in stock. I have a lot of the latter since someone donated ~110 different values of 1000pcs 1% 50ppm resistors to the local hackpace. I've got about 50 of every value; I doubt the other 'spacers will ever use up the rest!

Oh that's a nice donation to have, I'd love to receive something like that. [emoji3]

[mnementh]

Ok Nixie fans riddle me this. BOM says 10k 1/3W Diagram says 18k and these toasted ones read 39k 

They are the current limiting resistors btw.

Carbon compisition resisitors, which I presume those are, have two relevant characteristics compared with metal film resistors. CC resistors tend to drift high, and they are relatively tolerant of surges.

Well these ones clearly have failed and those types are always high on my list of suspects when things go wrong and replacing these with their equivalent ones in square edge or metal film types is preferable, as recommended by Mr Carlson,

Carbon composition resistors should be reserved for selling to audiofools

Things that bugger up carbon composition resistors: vibration, applying voltage, heat, moisture, age, moon phase, looking at the stripes too long.

Surges; that's what those nice hybrid resistors are for these days.

Quite correct. 

Are they just the bias ballast resistors, or are they actually in the signal path? If not, then no reason not to replace with metal film resistors. Even if they are in the signal path it probably won't matter, as old & slow as that thing is.


I remember back when I was very young... I used to scavenge all the glass-substrate film resistors out of old color TVs, then soak and scrape the coating and caps off. The resulting semiconductor-coated glass cylinders (they typically ranged from 3mm x 10mm to 8mm x 100mm or so) simply fascinated me; there were so many variations in the translucent color, and the cut pattern was so "Sci-Fi Story Doomsday Device" looking.

I used to collect them in groups and make enclosures with lights behind them, then imagine them as the energy source in my very own  "personal LASER"; built from scratch to do... well, whatever I damn well wanted to do, it was a fekking LASER, man!     And then, after Star Wars, and the oodles of books... I of course imagined them as Khyber crystals and fabri-cobbled, then as a teen in school I actually machined, my own LASER swords (yes, I know they're commonly called "light sabers") around them decades before places like Master Replica and Ultra ever imagined making them.

I never dreamed I'd one day be able to buy such a thing as a hearing-aid-battery-powered LASER pointer for four bits, or a real VISIBLE LIGHT (ZOMG!!!) green or blue LASER pencil capable of emitting actual destructive energy for the price of a sandwich & chips... and that they'd all be solid-state devices. Honestly, it STILL boggles my mind. 

Nice. I could do with a set like that. Very expensive though. £300+ for a proper development kit. Bought a whole book of cheap Royal Ohm resistors for development. Unfortunately I run a "swept bench" i.e. throw components at a design and then sweep them into a bag when done. So I'm already running out of loads of values.

Decided next time to just buy Vishay MRS25's on demand and spreadsheet it properly. And you know what, check the sodding back order lead on the things https://uk.rs-online.com/web/p/through-hole-fixed-resistors/6833165/

There are a number of vendors on AliEx selling assortments of cut-reel reclaimed passives of all sorts; I've even bought 1/2 watt axials in corrugated cardboard magazine format from there that have to be 40 years old.

I run a swept bench too... I sweep them all into a plastic shoebox.   

I have one for resistors, one for caps, one for semis and one for "Damifino". These are what I dig around in first when I'm just noodling around on hobby projects or, when I need some time doing a repetitive activity for "mental floss", I'll sort them into little pill boxes. :p


mnem
https://youtu.be/vOjPBBvBe2c

[tggzzz]

Oh that's a nice donation to have, I'd love to receive something like that. [emoji3]

We've had quite a few other tasty donations. A Telequipment DM63 dual-beam storage scope (needs recapping), a Tek2245 and Agilent 54621 (both work nicely) spring to mind. Plus a semi-random assortment of components that might be useful if you (a) know they exist and (b) can find them.

[beanflying]

Had a little order up on Vishay 2W 500V (no such thing as overkill) rated resistors from 5-50k for stock and this job. I could have paralleled some 1/4w metal films I have but it would be a real bodge.

Looking at the board it has been very hot and there is no tracks left so either the resistors were replaced by some hack with a 200W iron at some stage or the original resistors failed hot. The datasheet I found on the Nixies http://www.tube-tester.com/sites/nixie/dat_arch/ITT-dat02.pdf indicates 18k at 200V is about right for 3mA so I will go with that.

Also needed a new display time pot/switch as the old one is stuffed.

[neo]

My 0-12 just stopped displaying a trace. Nothing catastrophic happened and the rear of the CRT still lights up, worked just fine last night.
Exact coarse of events, crt was loose and so it rotated when i moved it.
I open it and very carefully rotated it back.
I take extreme caution and tighten the clamp.
Quick test, still works and is even.
Back in the case it goes and to bed i went.
No trace this morning. 

Anyone got any hints or ideas? I hope i didn't screw damage it.

*FIXED*
Don't ask me how but all i did was i yelled, "Work you miserable cur!" at it.
Imagine my surprise when that worked.