Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

All old style incandescent fittings have issues, bayonet as well. 
Heat is the killer where the metal holder bonding to the fitting can let go so it won't even hold a bulb or the plunger pin springs weaken with repeated heat cycling over the years resulting in insufficient contact pressure which you could liken to trying to power a bulb via a miniscule spark gap. 
Result = bulbs that don't last long vs bulbs in good bayonet fittings that seemingly last for years and years.

You missed out what I consider to be the real main problem with bayonet holders is where the spring load contact pins embed themselves into the solder pads on the end of the lamp over a period of time. This often brings a shockingly dangerous failure mode IMO which people can easily fall foul of when trying to change the lamp. The glass detaches itself from the base and then, more often than not, breaks, possibly injuring the lamp changer and also leaving potentially live filament stamens exposed ready to shock anybody foolish enough not to switch at the circuit breaker first when changing the lamp. I have also seen many times when the glass envelope, complete with the filament stamens, separate from the brass lamp cap, leaving the cap in the holder, wedged in by the embedded pins with two short wires exposed from the solder pads, waiting for someone's finger to slip inside the brass cap Removing a cap where that has happened can be rather tricky to say the least, especially as is the case with my Mothers-in Laws chandeliers   

[mnementh]

Specmaster you need to come to Discord and defend the honour of Mr C.

Disparaging remarks have been made.

That'd better not be this Mr. C. [Sound of cutlery draw rattling.] 

On a separate note, is it strange that I've started to take personal offence if I spot the GPSDO output I'm keeping an eye on wander even slightly over 100 ppt error? A few weeks back I'd have been happy for it to average 1 ppb error, let alone never wander anywhere near it.

What's that Mr. Cottontail? Yes, of course I'd like to hear how to reduce my measurement's confidence interval by \$\frac{1}{\sqrt{2}}\$.

Mmmmhmmm... may be a variant of BDADD... I recommend you take two Agilent Catalogs and do what comes naturally, then call us in the morning. Normally should not be taken internally; but hey, do what you have to.

mnem
BDADD: Bouncing Digit Attention Deficit Disorder - When you don't hear your wife/kids/boss calling your name because you're too busy watching those digits flip on a stack of such instruments and trying to figure out the pattern; or because you just noticed that two or more of them seem to be in sync. (see also: FDDS, FDDAS)

[mnementh]

Someone having a pop at Mr C, really, why is that then 

Sorry but I can't at the moment, upto my neck in things here, not least of all trying to repair my glasses, I really should go and get my eyes tested, I'm overdue for an eye test as SpecSavers keep on reminding me, but I'm reluctant to go and do that why this Johnson variety is so rampant. On top of that, I found myself chewing on my crown at the same as chewing a date, the sticky date pulled it off  and I have my youngest having a crisis as his squeeze has gone and dumped him  Middle son has had the Moderna Covid vaccine and is also a bit down and with a sore arm, which apparently is common with that vaccine.

Hopefully next week I shall be able to join on discord once again, fingers crossed.

Aww, dood... hope things lighten up for you a little in the coming week. We aren't doing anything important; Discord is supposed to be just wasted electron displacement anyways.

mnem
 

[mnementh]

Today's XKCD: 

WTF is that a real thing or someone's idea of a joke 

Hey, no stupider than Lenovo's rectangular power plug that looks just like a USB... 

mnem
I'm all out of pithy.

[tautech]

All old style incandescent fittings have issues, bayonet as well. 
Heat is the killer where the metal holder bonding to the fitting can let go so it won't even hold a bulb or the plunger pin springs weaken with repeated heat cycling over the years resulting in insufficient contact pressure which you could liken to trying to power a bulb via a miniscule spark gap. 
Result = bulbs that don't last long vs bulbs in good bayonet fittings that seemingly last for years and years.

You missed out what I consider to be the real main problem with bayonet holders is where the spring load contact pins embed themselves into the solder pads on the end of the lamp over a period of time. This often brings a shockingly dangerous failure mode IMO which people can easily fall foul of when trying to change the lamp. The glass detaches itself from the base and then, more often than not, breaks, possibly injuring the lamp changer and also leaving potentially live filament stamens exposed ready to shock anybody foolish enough not to switch at the circuit breaker first when changing the lamp. I have also seen many times when the glass envelope, complete with the filament stamens, separate from the brass lamp cap, leaving the cap in the holder, wedged in by the embedded pins with two short wires exposed from the solder pads, waiting for someone's finger to slip inside the brass cap Removing a cap where that has happened can be rather tricky to say the least, especially as is the case with my Mothers-in Laws chandeliers 

Experienced that also and far less common now everything changed to that lead free muck.

[mnementh]

All old style incandescent fittings have issues, bayonet as well. 
Heat is the killer where the metal holder bonding to the fitting can let go so it won't even hold a bulb or the plunger pin springs weaken with repeated heat cycling over the years resulting in insufficient contact pressure which you could liken to trying to power a bulb via a miniscule spark gap. 
Result = bulbs that don't last long vs bulbs in good bayonet fittings that seemingly last for years and years.

You missed out what I consider to be the real main problem with bayonet holders is where the spring load contact pins embed themselves into the solder pads on the end of the lamp over a period of time. This often brings a shockingly dangerous failure mode IMO which people can easily fall foul of when trying to change the lamp. The glass detaches itself from the base and then, more often than not, breaks, possibly injuring the lamp changer and also leaving potentially live filament stamens exposed ready to shock anybody foolish enough not to switch at the circuit breaker first when changing the lamp. I have also seen many times when the glass envelope, complete with the filament stamens, separate from the brass lamp cap, leaving the cap in the holder, wedged in by the embedded pins with two short wires exposed from the solder pads, waiting for someone's finger to slip inside the brass cap Removing a cap where that has happened can be rather tricky to say the least, especially as is the case with my Mothers-in Laws chandeliers 

Oh, the E26/E27 base (medium Edison base for you heathens) has its own variant of that... ever since they started sometimes making the threaded part of both the bulb and the lamp socket out of plain aluminum for cost. As you may imagine, if you combine a fixture and a bulb both with said evil aluminum threads, there is a more than 50/50 chance that after a year or three of repeated heating/cooling cycles and moisture in the air, it'll gall up as you unscrew and do exactly as you describe.

mnem
*blub-ity*

[mnementh]

WTF is that a real thing or someone's idea of a joke 

It's  joke. I can't believe that there is still someone around here who doesn't know XKCD, let alone immediately recognize the cartoon style. Go here: https://xkcd.com, we'll see you in few days....

Nope, can't say that I'd seen any before, that plug had all the hallmarks of a quick artist sketch up for a mock-up of a new catalogue page layout for a new product, of which I have seen quite a few over the years.

dude... I've been posting XKCDs in here for literally years. Just do a search for mnem xkcd in this thread... 

https://www.google.com/search?q=mnem+xkcd+site:https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/

In fact, I recently started rereading it  for like the 13th time as part of my bedtime wind-down ritual... and if I find one that is especially good, or fits at that moment, I've been posting it just before I crawl into bed.

   https://xkcd.com/958/

mnem
There's a XKCD for that...

[Wolfgang]

Ah yea you got a germanium fuse now 

On subject of transistors I’m considering buying a huge bag of 2N series TO39 GP medium power jobbies at the moment for £20 “just in case”. Insane or not?

I had a feeling in my gut which is why I went ahead and ordered 2 more even though I had one on hand. Besides, this guy uses a shit load of the 2N2207 and as you recall I did have one with a tin whisker short. So we gots some spares. 

I'd buy the TO39's.

If you listen really closely you can hear the whiskers grow in your replacement part. 
When looking at the circuit I cant see that a piece of jellybean Silicon wont do the job reliably and forever ... or is it good old Germaniumphoolery ... 

[med6753]

If you listen really closely you can hear the whiskers grow in your replacement part. 
When looking at the circuit I cant see that a piece of jellybean Silicon wont do the job reliably and forever ... or is it good old Germaniumphoolery ... 

I was tempted to stick in a sillycon 2N3906 and see if it would work. I also have on order NTE-126 which is the cross for 2N2207. So while I prefer the OE part I do have options if a tin whisker suddenly appears.

[Neomys Sapiens]

Today's XKCD: 

WTF is that a real thing or someone's idea of a joke 

Hey, no stupider than Lenovo's rectangular power plug that looks just like a USB... 

mnem
I'm all out of pithy.

Talking of USB and stoopid: The Toshiba Laptop issued by my company has 2 USB and a Network jack on the right side. The network jack seems to be connected in parallel with the one in the docking station. When you inadvertently insert an USB-stick or plug into the network jack (where it fits snugly) your connection goes down.

[GreyWoolfe]

Today's XKCD: 

WTF is that a real thing or someone's idea of a joke 

Hey, no stupider than Lenovo's rectangular power plug that looks just like a USB... 

mnem
I'm all out of pithy.

Talking of USB and stoopid: The Toshiba Laptop issued by my company has 2 USB and a Network jack on the right side. The network jack seems to be connected in parallel with the one in the docking station. When you inadvertently insert an USB-stick or plug into the network jack (where it fits snugly) your connection goes down.

Nice to know I am not the only buffoon to do that.  I also have a company laptop that is a Lenovo T460.  I think the power plug is weird but at least the power plug for the docking station and the laptop are the same.

[mnementh]

OMG... when I was working as an ASP for HP/Dell Corporate support back in the day... that was one of the most common "causes of death" for MB replacement: the ethernet jack completely Euckered by some fuckwit repeatedly jamming a USB stick in the port and smashing the pins so their "network cable" can't work.

And yes, on models where there was a USB or two very close to the ethernet port there were a lot more such casualties... but there were still far too many on models where there was nothing but the ethernet in the vicinity. 

mnem
It is impossible to make any connector foolproof; the fools are too fucking inventive.

[GreyWoolfe]

OMG... when I was working as an ASP for HP/Dell Corporate support back in the day... that was one of the most common "causes of death" for MB replacement: the ethernet jack completely Euckered by some fuckwit repeatedly jamming a USB stick in the port and smashing the pins so their "network cable" can't work.

And yes, on models where there was a USB or two very close to the ethernet port there were a lot more such casualties... but there were still far too many on models where there was nothing but the ethernet in the vicinity. 

mnem
It is impossible to make any connector foolproof; the fools are too fucking inventive.

For me, it is neither desktop/laptop/dock.  It is a specialized image printer that is actually bolted to countertops for "security purposes"  There isn't much room between them and the wall so I have to use my penis fingers to find my way as I always unplug the network cable so it doesn't start to print when I am inside it.  I have done it a couple of times over the years. Thankfully, I am gentle so I haven't fuckerized one yet as they were $8,000 new in quantity when we bought over a thousand of them.

[0culus]

I recently picked up an interesting Tek plug in unit, a Type O op amp plug in. It can do a lot of different things; highly recommend taking a peek at the Applications section of the manual for more.

Of course there is an array of test fixtures for it (that plug into the banana jacks) that I'll have to find now. 

[0culus]

And another, better view of the front panel.

[Brumby]

I recently picked up an interesting Tek plug in unit, a Type O op amp plug in. It can do a lot of different things; highly recommend taking a peek at the Applications section of the manual for more.

Indeed.  Looks like it could be fun.

Of course there is an array of test fixtures for it (that plug into the banana jacks) that I'll have to find now. 

AAAAAAND we're off down the slippery slope once again!!   

[med6753]

Replacement Q564 installed top side directly onto the ceramic strip.



Trace prior.



Trace now. Horizontal issue fixed. Trace is pin point sharp.  HV seems OK although I haven't checked it yet. Sweep timing on both A and B working fine. Same with Trigger on both A and B but the real test will be with a signal.



Next issue is the Vertical. It's completely dead. Won't pass a signal plus cannot move trace vertically. The vertical circuit is all sand state except for one vacuum tube.

[med6753]

The lower section of the vertical amplifier. Those 2 cans are additional filtering for the plug-in and are going to be replaced once the scope is fully functional.



The upper portion of the vertical amplifier. Later today we are going to get very friendly.  A quick check shows that the transistors are all silicon and while obsolete seem to be readily available.

[tautech]

Quick squiz at the schematic drew my focus to the 2 now very old zeners. 

[AVGresponding]

All old style incandescent fittings have issues, bayonet as well. 
Heat is the killer where the metal holder bonding to the fitting can let go so it won't even hold a bulb or the plunger pin springs weaken with repeated heat cycling over the years resulting in insufficient contact pressure which you could liken to trying to power a bulb via a miniscule spark gap. 
Result = bulbs that don't last long vs bulbs in good bayonet fittings that seemingly last for years and years.

You missed out what I consider to be the real main problem with bayonet holders is where the spring load contact pins embed themselves into the solder pads on the end of the lamp over a period of time. This often brings a shockingly dangerous failure mode IMO which people can easily fall foul of when trying to change the lamp. The glass detaches itself from the base and then, more often than not, breaks, possibly injuring the lamp changer and also leaving potentially live filament stamens exposed ready to shock anybody foolish enough not to switch at the circuit breaker first when changing the lamp. I have also seen many times when the glass envelope, complete with the filament stamens, separate from the brass lamp cap, leaving the cap in the holder, wedged in by the embedded pins with two short wires exposed from the solder pads, waiting for someone's finger to slip inside the brass cap Removing a cap where that has happened can be rather tricky to say the least, especially as is the case with my Mothers-in Laws chandeliers 

This happens when the lamp is too powerful for the rating of the lamp-holder, and is as likely to happen with a screw as a bayonet in my experience. I would also like to point out that on a BC the metal body is either earthed or more often not connected to anything at all, electrically speaking, whereas the ES body is live, and if the person that terminated it screwed up it's going to be the phase/line as well (neutral is considered to be a live conductor as well as the phase/line).

[mansaxel]

This happens when the lamp is too powerful for the rating of the lamp-holder, and is as likely to happen with a screw as a bayonet in my experience. I would also like to point out that on a BC the metal body is either earthed or more often not connected to anything at all, electrically speaking, whereas the ES body is live, and if the person that terminated it screwed up it's going to be the phase/line as well (neutral is considered to be a live conductor as well as the phase/line).

I think it is dangerous and severely sub-optimal to ever assume anything except "2 live conductors" (and hopefully ground) for single-phase mains. In an Edison threaded socket, which is the dominant one here, both sides thread and bottom pole are always assumed to be live.

Of course, in three-phase supplies, where shit needs to be right for real, this is not the case. 

Our continental mains plugs, being unpolarized, certainly help instill the notion.

They OTOH create musician voodoo, where there's an optimum orientation of the mains plug of ones guitar amp, an idea that is on par with the concept that a 2m audio-phool mains cable at the end of 200m Al and Cu with PVC  insulation and wire-nuts will make things sound better.

[Robert763]

At school a few weeks ago, my teacher announced that they had some test gear to get rid of, and we could take anything we wanted for free. I ended up scoring 3 things  

1. Hioki 3520 LCR meter

It's 30 years old and only 4 digits, but that's 4 digits more than I had before! (It can test at 40Hz–100KHz, so it's still a serious piece of gear, methinks.)

They also had a couple of giant demonstrator analog VOMs: we're talking movements probably a foot (30cm) wide. I'd have taken them for curiosity's sake, if not for the fact that I am already cripplingly short on space…


2. Leader LFG-1310 signal generator
It's a fairly standard purely analog gen (10MHz; sine, triangle, square waves; sweep; modulation). I still plan to get an arb generator at some point, this is still an upgrade from what I had before, which was no signal gen at all! One pot needed a clean and lube to get rid of scratchiness, now it's perfect.

3. Hameg 407 oscilloscope (it's a hybrid analog and digital storage scope). Its digital storage side isn't anywhere near as useful as the Rigol DS1054Z I already have, but it's nice to have an analog scope finally!

That Hioki is actually a very good LCR meter.  multi frequency and 0.3% accuracy.
I'd happily give you a brand new Tenma handheld LCR meter in exchange for it.

[AVGresponding]

This happens when the lamp is too powerful for the rating of the lamp-holder, and is as likely to happen with a screw as a bayonet in my experience. I would also like to point out that on a BC the metal body is either earthed or more often not connected to anything at all, electrically speaking, whereas the ES body is live, and if the person that terminated it screwed up it's going to be the phase/line as well (neutral is considered to be a live conductor as well as the phase/line).

I think it is dangerous and severely sub-optimal to ever assume anything except "2 live conductors" (and hopefully ground) for single-phase mains. In an Edison threaded socket, which is the dominant one here, both sides thread and bottom pole are always assumed to be live.

Of course, in three-phase supplies, where shit needs to be right for real, this is not the case. 

Our continental mains plugs, being unpolarized, certainly help instill the notion.

They OTOH create musician voodoo, where there's an optimum orientation of the mains plug of ones guitar amp, an idea that is on par with the concept that a 2m audio-phool mains cable at the end of 200m Al and Cu with PVC  insulation and wire-nuts will make things sound better.

Neutral is defined as a live conductor in the regulations. Depending on system current draw and earth bonding method/quality, it may have considerable potential wrt earth. It is NOT ever "safe" to touch the neutral in an energised circuit. In certain fault conditions it is not safe to touch the neutral even in non-energised circuits.

The BC lamp holder body is NEVER live (barring incredible and bizarre circumstances), meaning never connected to either phase/line or neutral and is therefore far, far superior to the ES in terms of safety.

It's also worth noting that in some countries, the US for example, the "neutral" may be another phase, where higher currents are needed eg for a tumble dryer.

[med6753]

It's also worth noting that in some countries, the US for example, the "neutral" may be another phase, where higher currents are needed eg for a tumble dryer.[/color][/size][/b]

Not quite. Residential wiring in the US is single phase. The pole transformer is fed with one HV primary. The secondary of the pole transformer is center tapped grounded. On each side of the center tap is 120V measured to the center tap. Measure across the 2 hots and it's 240V. It is sometimes called "split phase" because the hots are 180 degrees out from each other. But in reality it's single phase.

Devices requiring 240V typically will have 2 hots with ground but no neutral. But some 240V devices have 120V circuits so they require 2 hots, a neutral, and a ground. And as always the neutral and ground are NEVER bonded together at the device. Only at the breaker box.       

[tggzzz]

Trivia time: what wallpaper should I use on my phone?

Constraint: 320 high, 240 wide. Yes, it is a phone, not a computer with a phone as an afterthought.