Test Equipment Anonymous (TEA) group therapy thread

[Neomys Sapiens]

- An 84LS chip. Yes 84 not 74. Sure knew about the 54 military prefix, but 84 no, never heard of that one. Some more Googling required again...

Interesting. I know of the 64xx series that were a Texas Instruments Industrial Grade (−40 °C to +85 °C) that sat in between the standard 74xx and the milspec 54xx. It was only around for a short while.

Sometimes you'll find earlier versions of TTL logic that would have different numbers depending on the manufacturer before it was all standardised to 74 and 54 prefixes.


[EDIT] It seems that 84xx was also used for Industrial Grade parts in Europe. (−25 °C to +85 °C)

At least at TI, all the 55/75 types fell under the Interface category and were listed in a separate databook.

[bd139]

Oh Tektronix you make me so happy...

[Vince]

Oh Tektronix you make me so happy...

So you mean the fault will be diagnosed within the hour, is that what you imply ?! 

Clock is ticking....

[bd139]

Nah put it away now. Really have to move house now. This was a welcome distraction

[Vince]

So yeah, I HATE those trimmers too !

Sounds like someone has been guilty of using the wrong type of contact cleaner on those.

Having torn the scope apart back then to restore it, I sincerely doubt this scope has ever seen any kind of servicing in its life... and trimmers should not be cleaned anyway, they aren't pot on the front panel. You set them once at the factory, maybe tweak them once if the scope is lucky to ever be calibrated again in its life, and that's about it.

To me it felt simply like the plastic aged, helped with the heat, and since the plastic shaft was so thin, 45 years later it didn't need much help to snap...just the weight of the knob (the boards are mounted vertically, plus the shipping bouncing it around... that was plenty enough I think..

[Vince]

Any other colours I am not aware of ?! 

There you go, now you can build your tant-cap-rainbow.

 

Wow.... a rainbow indeed ! Purple, white/beige, brown, and black as BD said.... someone for everyone ! 

Me I prefer the bright yellow ones. Like the colour, plus it makes those horror caps easier to spot !! 

Second pic shows also an example of the one shaped like a silver mica as BD mentioned... hmmm... trap for young players here, didn't know about that, will keep that in mind...

[bd139]

Any other colours I am not aware of ?! 

There you go, now you can build your tant-cap-rainbow.

 

Wow.... a rainbow indeed ! Purple, white/beige, brown, and black as BD said.... someone for everyone ! 

Me I prefer the bright yellow ones. Like the colour, plus it makes those horror caps easier to spot !! 

Second pic shows also an example of the one shaped like a silver mica as BD mentioned... hmmm... trap for young players here, didn't know about that, will keep that in mind...

Actually they are even worse than that. Below is the one that got me for nearly 2 hours. The brown one. The whole unit it was in was stuffed with silver mica capacitors which didn't help



This was how deep the surgery was to find that bastard...



I won in the end.

[duckduck]

At least my expense on this Advantest R6144 unit is still in the tens of dollars, so it is faaar below the current market value so I'm still ahead (not counting time, but who counts that? )

But bd139, you can't drop a juicy hint like that and not elaborate!, what is this book you speak of?!



(currently 6 smirnoffs, 1 shochu, and 2 beers in to the long road of inebriation.. fun! )

That is a suitable amount of alcohol to ingest before hitting eBay with the credit card 

As for the book, been mulling the idea of writing a book for about ten years. Subject matter is basically all those bits of info that everyone should know before doing a Udemy “how to code” tutorial. I encounter a lot of people who can’t even visualise what a computer or network looks like past some opaque magic and expect me to fill the gaps in 

I don't know what they are teaching the kids nowadays. I remember explaining the concept of "virtual memory" (the 2000's-era Windows disk cache variety, not the 64-bit memory space variety) to one of the developers in my IT department years ago.  I think there are many fledgling software developers that take everything at the OS-level and below (down to hardware) completely for granted and give no thought to it until they are punched in the face by reality. To me, the advantage of university is having your lessons put in context (history, business, computational theory, computer design, OS design, project management, und so weiter). Also, get off of my lawn.

[Ice-Tea]

A request to go against the spirit of the group:

At work, we've established that we need a Timing Interval Analyser. I tried buying the one Robert had for sale, but was too late. Does anyone else have a hp 5371A or one of the Yokogawa TA series, or similar, they'd be willing to part with?

It needs to be reasonably well working (another break with the spirit) and it can cost some money (again, against the very moral fibre!) but not "Korea instrument reseller insane".  An official-looking invoice is a cool thing.  In Europe is a definite bonus.

Ice-Tea?

Let me see tomorrow

Don't have it or anything like it...

Have you seen this: https://www.zendamateur-marktplaats.nl/zend-ontvangst-cat/frequentiecounters/hp-5371a-frequency-and-time-interval-analyzer-26254.html#listing_tab

[Vince]

Any other colours I am not aware of ?! 

There you go, now you can build your tant-cap-rainbow.

 

Wow.... a rainbow indeed ! Purple, white/beige, brown, and black as BD said.... someone for everyone ! 

Me I prefer the bright yellow ones. Like the colour, plus it makes those horror caps easier to spot !! 

Second pic shows also an example of the one shaped like a silver mica as BD mentioned... hmmm... trap for young players here, didn't know about that, will keep that in mind...

Actually they are even worse than that. Below is the one that got me for nearly 2 hours. The brown one. The whole unit it was in was stuffed with silver mica capacitors which didn't help



This was how deep the surgery was to find that bastard...



I won in the end.

Hmmm... it's really big as well, helps mistaking it with a mica 

I admire your ability to work on that scope with on a bench so cramped. Were it me it would take only a split second to inadvertently knock half of the stuff off the bench 

Can't believe you got rid of that cool SA plugin  ! 

OH now that reminds me that before you left for your 6 months sabbatical away from society, you had just bought a lovely 7000 series transistor curve tracer, didn't you ?! So you got rid of that as well, ARRRRRRRRGH !!! 

[bd139]

I will make amends. My purchase rate of TE is higher than ever 

I got rid of the 7L12 because quite frankly it scared me. It could literally turn into a brick at any moment with no hope of repair. There are literally no parts mules for it or anything.

[tggzzz]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

And now for something completely different. A small 50 ohm load. 10KW. And yes, that's the coax connector on the front 

Ah, I'm glad someone took a photo of that. Not exactly an N/BNC/SMA connector, though.

[Robert763]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

And now for something completely different. A small 50 ohm load. 10KW. And yes, that's the coax connector on the front 

Ah, I'm glad someone took a photo of that. Not exactly an N/BNC/SMA connector, though.

yep 10kW into 50R is roughly 707V RMS, 1kV peak so minimum connector is a C type or HN. 

[ch_scr]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

So what did I bag?

(...)
The Mullard Transistor Circuits Manual ...

Damn that is nice bedtime lecture, I can see why it's highly sought after!

[tggzzz]

OK, so my haul was

• a Fluke 515a portable calibrator for £20. Quick check shows Vdc excellent, µVdc cockeyed, resistors good, Vac not bad, unlikely the NiCd battery works, missing the unique front panel switch which I'll probably have to "improvise"
• three Muirhead decade resistors for £5. Looks good.
• Cropico 4 decade resistor box. A few resistors o/c, but can be replaced
• and the thing below for £5, which is probably as near as I will get to having a slice of the one lying around in my first job

[25 CPS]

- An 84LS chip. Yes 84 not 74. Sure knew about the 54 military prefix, but 84 no, never heard of that one. Some more Googling required again...

Interesting. I know of the 64xx series that were a Texas Instruments Industrial Grade (−40 °C to +85 °C) that sat in between the standard 74xx and the milspec 54xx. It was only around for a short while.

Sometimes you'll find earlier versions of TTL logic that would have different numbers depending on the manufacturer before it was all standardised to 74 and 54 prefixes.


[EDIT] It seems that 84xx was also used for Industrial Grade parts in Europe. (−25 °C to +85 °C)

Yes.  Back in 2019, I did a bit of reverse engineering a card that came out of a Siemens-Du Wag LRV and it was all SN84##N series TTL chips on there but they were all TI chips except for a couple, very small number, of Siemens-Halske which looked like they may have been replacements installed during previous repairs.  My recommendation was to go with standard 74-type replacements unless the card cage was known to get REALLY hot, in which case 54-type military would probably be a better replacement since 84-series stuff looked hard to get at the time.

[factory]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

So what did I bag?


Next we have the HP 3311A function generator. Again it works absolutely fine. Paid £20 for it too. One of the feet fell to bits in the car but this is sort of expected.



Very nice



Will work out a new foot solution to this...

Didn't you 3DP one of those feet sometime ago?
Don't know why, but that rear foot always seems to crumble, on that type of case, the front one for the tilting bail, must be made from a different plastic.

David

[Robert763]

OK, so my haul was

• a Fluke 515a portable calibrator for £20. Quick check shows Vdc excellent, µVdc cockeyed, resistors good, Vac not bad, missing the unique front panel switch
• three Muirhead decade resistors for £5. Looks good.
• Cropico 4 decade resistor box. A few resistors o/c, but can be replaced
• and the thing below, which is probably as near as I will get to having a slice of the one lying around in my first job

Ooh submarine telephone cable?

[mnementh]

   damn you. damn you to... New Jersey. 

mnem

You’re welcome.       -Pat

On the Bench Tonight: INFINITY RS-3000 Driver Refurb
...Next up will be the relatively boring part of doing cabinet rehab. I'm knackered, so we'll visit that tomorrow after all the cement has time to cure overnight.   

mnem

On the Bench Tonight: INFINITY RS-3000 Cabinet Rehabilitation And Assembly



One of these speakers had drop damage on the corner; it broke this corner of the grill frame and made a ding in the top edge of the speaker with a noticeable separation right at the seam.

I almost passed on these speakers as it had been a long time since I did such repairs; but then the fixer in me took over, saying "You know how to fix this; just do it ya fukkin' baby!" After a little goading from Pat, here they are on my bench.




Here I am doing rehab on the speaker grilles. This is the broken corner; as there is little contact area at the diagonal crack, I printed up a little corner bracket to make a lap joint with the epoxy. Note the little holes to give the epoxy something to sink into. This took about 5 minutes in fusion360, then 15 minutes to print at 0.28mm DRAFT Layer height.

The broken support peg will just be epoxied in place; there's a lot of contact area there. To give the epoxy something to bond to, I've made a lot of crosshatch scoremarks with a sharp paring knife on the mating surfaces. Note the scrap of cardboard between the grillcloth and the frame as a drip barrier. Epoxy soaking through the grillcloth is very noticeable. 




The finished repair. I tacked down the edges of the grill cloth that had come loose by touching the edges with a soldering iron; I used the hot-knife blade and temp at 250°C. This is essentially how they make the grills at the factory.




The correct way to "renew" this speaker would be to replace the grillcloth; however I'm already into these for $40, and there isn't budget for that in either money or assache. I'll clean things up as best I can and see how good I can make it look.

Cleaning is done first with a towel soaked in Windex. I support the back of the grillcloth with my hand and arm and scrub gently against them; moving from area to area until the entire surface of the grill has been scrubbed. Any spots that don't come clean with Windex (like tracks on the back from marshmallowy speaker roll foam) will get followup with a towel soaked in IPA. In both cases stop and re-wet the towel frequently. If grillcloth rips or stays stretched when you try this, it was already past time to replace it.




Next problem to address is slubs in the fabric from where it got snagged on stuff over its life. I used to do this with a Bic lighter, but I found that it is too easy to burn a hole in the cloth if you're just a moment too slow pulling it away.

A small hot air gun like this one for heat-shrink tubing works a treat; it makes the polyester threads shrink away and much less obvious. Start about a foot away and bring the nozzle in while watching the slub(s) you're working on; the instant you see them start to shrivel up tilt the nozzle away. Repeat until you stop "seeing just one more really ugly poker"...




Part of the damage was a split seam right along this edge with ~2mm gap; my repair was to mask right up to the edge of the seam, then poke epoxy into the gap with a paring knife. (Sorry; no before pic  ) Then wipe off excess with a IPA-soaked towel, clamp the seam as  seen here and wipe off the sqweezage with the IPA-soaked towel. Set it aside and wait til the next day. I SAID WAIT TIL NEXT THE DAY, DAMMIT!!!




Next morning I undo the clamp and I'm greeted with this beautiful sight. I can see there is a tiny little bit of epoxy extruded right on the edge, and of course the first instinct is to pick at it and try to make it perfectly flush. *smacks own fingers* No. You know this only results in pain and misery, like picking at sunburn scabs...




Resisting the urge, I do as I know from painful experience is the right way to finish this repair: Peel off the masking tape, then wipe it all down with a IPA-soaked towel.  Not perfect, but close enough that I know only I will notice. 




If there's one thing that pisses me off with a used speaker, it's to find the bottom all tore up from monkey-butts who drag a bare speaker across the floor.






It takes pretty much nothing to just pop a few of these on the bottom, which will prevent easily 90% of such mishaps from scarring your speakers, and it helps decouple them from the floor so the bass doesn't make the house rattle.

Just do it, FFS.


   

Last step before reassembly is to do a quick checkup of the XOs; these are a nice compact design well-supported by the spring-connector bung and lots of hot-snot. No loose inductors, no leaking or bloaty caps and no cracked solder joints. Caps/resistors measure well within reasonable "sanity values" indicating no opens or shorts, so no motivation to dismantle for further testing.

Not sure what this particular variant of the ubiquitous 2nd order L-R filter is called; but I'm sure there are plenty in here who can bust my chops aboot it.




Any time I open up a speaker, I re-tension the connectors before reassembling. It takes just the gentlest squeeze with the pliers; I usually prefer something with smooth jaws, like my Xuron 3mm flat-bill pliers here.




And here's the fixer's moment of joy: finally time to reinstall the drivers. I do this by hand with a bit-type driver; the magnetized end holds the screw so you can balance the speaker while getting it started, and by choosing a new bit I can make sure I minimize slippage which leaves ugly scars on the screw heads. Plus it's just too damned easy with the drill/driver to slip and poke a hole in your just refurbished driver. Much  follows.

As with anything assembled using machine screws, by hand you can turn the screw backwards and feel the bump at the edge of the old "thread"; looking for this with self-tapping screws in wood and plastic helps you make sure not to strip out the hole and makes reinstalling the screw much easier.

This tactic also helps you make sure easily-deformed sheetmetal like the speaker basket doesn't get bunged up, making the speaker not seal properly. This can cause buzzing or whistling as moving air passes through that gap.


   

And here are the money shots: Both speakers finished and ready to go into service.   

Guess I need to get this     up on the bench next...

mnem
 

[Robert763]

- An 84LS chip. Yes 84 not 74. Sure knew about the 54 military prefix, but 84 no, never heard of that one. Some more Googling required again...

Interesting. I know of the 64xx series that were a Texas Instruments Industrial Grade (−40 °C to +85 °C) that sat in between the standard 74xx and the milspec 54xx. It was only around for a short while.

Sometimes you'll find earlier versions of TTL logic that would have different numbers depending on the manufacturer before it was all standardised to 74 and 54 prefixes.


[EDIT] It seems that 84xx was also used for Industrial Grade parts in Europe. (−25 °C to +85 °C)

Yes.  Back in 2019, I did a bit of reverse engineering a card that came out of a Siemens-Du Wag LRV and it was all SN84##N series TTL chips on there but they were all TI chips except for a couple, very small number, of Siemens-Halske which looked like they may have been replacements installed during previous repairs.  My recommendation was to go with standard 74-type replacements unless the card cage was known to get REALLY hot, in which case 54-type military would probably be a better replacement since 84-series stuff looked hard to get at the time.

Bear in mind that GENERALLY the silicon die in a automotive, industrial or military/aerospace temp range IC is the same as a consumer one. The difference is limited to packaging, testing and sometimes reduced eectrical specifications. That said even if a "plastic" packaged industrial chip looks identical to a consumer it might have different moulding material, leadframe and or bondwire.
That said I've seen plenty of aerospace kit that was qualified for -25 to +55 but used standard commercial plastic ICs. THe equipment maker has decided it is OK and carries the risk. This might be basted on their own testing.

[bd139]

OK, so my haul was

• a Fluke 515a portable calibrator for £20. Quick check shows Vdc excellent, µVdc cockeyed, resistors good, Vac not bad, unlikely the NiCd battery works, missing the unique front panel switch which I'll probably have to "improvise"
• three Muirhead decade resistors for £5. Looks good.
• Cropico 4 decade resistor box. A few resistors o/c, but can be replaced
• and the thing below for £5, which is probably as near as I will get to having a slice of the one lying around in my first job

Excellent. Glad to see the 515A went to the right person.

As for the cable, that's a great ornament 

[bd139]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

So what did I bag?


Next we have the HP 3311A function generator. Again it works absolutely fine. Paid £20 for it too. One of the feet fell to bits in the car but this is sort of expected.



Very nice



Will work out a new foot solution to this...

Didn't you 3DP one of those feet sometime ago?
Don't know why, but that rear foot always seems to crumble, on that type of case, the front one for the tilting bail, must be made from a different plastic.

David

I probably did. Can't remember that far back. I blocked my escapades in 3d printing out of my mind so I don't go down that rabbit hole again. Then again, never know what might happen 

[factory]

I will make amends. My purchase rate of TE is higher than ever 

I got rid of the 7L12 because quite frankly it scared me. It could literally turn into a brick at any moment with no hope of repair. There are literally no parts mules for it or anything.

Looking at the pile of SA crap I got at the last PP auction, the HP 8557/8/9 SA plug-ins aren't any better, the same mechanical parts, switch wafers & knobs are broken/missing on most of them.
Clearly the mixer, Yig oscillator and attenuator are trouble too, judging by them either being missing or labelled as futzed, though I suspect some of that might have been the operators fault. 

David

[bd139]

Ok Newbury megapost. It has been 3 years since the last one. Bloody COVID.

So what did I bag?

(...)
The Mullard Transistor Circuits Manual ...

Damn that is nice bedtime lecture, I can see why it's highly sought after!

Yes it's an excellent book.

My original copy of it I stole from the local library but they sent me a postal shit-o-gram with a large fine so I handed it back on an amnesty day about a year later 

[mnementh]

...And now for something completely different. A small 50 ohm load. 10KW. And yes, that's the coax connector on the front 

There is something very, very wrong with me... I just got a raging nerd-boner. No idea what in the world I'd do with it... I just know I want... 

mnem
"Waaaatt...?"