Test Equipment Anonymous (TEA) group therapy thread

[Vgkid]

I have had good luck with these amass plugs , heavy little things.

[Specmaster]

Probably right. The only place I use 4-wire myself is power supply sense. I want the right voltage at the destination rather than the source.

Surely thats overkill, is there anything that it is that critical that a couple of mV is going to make any difference to? 

When it comes to measuring low value resistances I can appreciate the need for it but even then how many times is it so crucial unless your making shunts for meters etc?

[mnementh]

I never made much use in sense wires on PSUs, I just use fairly thick cables to minimize the voltage drop and that's close enough, most of my PSUs are not super accurate anyway.

But i like 4 terminal measurement for resistance when i'm dealing with things of 1 Ohm and under. These kelvin clips and my keithley dmm easily measures the tiny resistance of a few mm of copper wire with great repeatability.

I just go "ooh that's under an ohm". Much cheaper 

I go "Ooohhh... where did I leave my car keys this time..." because CRS is a bit** and she has puppies. 

I have had good luck with these amass plugs , heavy little things.

Ewww... yuckyputz.    

That's exactly the kind of plug we were griping about. 


mnem
*More than the sum of my volts*

[Ero-Shan]

Today I had the sudden urge to take a look at my HP3456As, lest you think I'm cured from TEA.

First one had a missing fuse (6.3 x 30 mm holder). While I have a bunch of that size, they're all 3 Amps or more instead of 250 mA. Looked at the other. It had a 5 x 20 mm fuse with to adapter caps. Put it in, switched on - nothing. Got it out, checked: blown.
Time for the Variac. Opened the DMM and connected a AC Amps meter across the fuse holder. I already suspected what would happen by looking at the mains transformer. And yes, with about 20 Volts of input the thing sucked already 100 mA. The yucky deposit on the transformer told the truth.  A short in one of the 17 V windings killed it.



On to the next. The "Gerät defekt" sticker across the display (some people do think placing stickers across displays is a good idea  ) leaves little hope. Now I have no fuse, as its plain impossible to get the blown one out of these adapter caps. Grr. I simple do the same as before: measure current across the empty fuse holder as I turn up the mains voltage. The current stays within its accepted range, and the display shows something like "0.302". It does not change when a voltage is applied at the terminals. First thing to do is measure the operating voltages. All but +33 V are good. Almost too easy, electrolytics C7 and C8 are the natural suspects. Once more I'm happy that I bought my LCR meter, as it quickly showed me that C7 had about 6 nF instead of 47 µF.



Replaced it and Bingo!, the DMM sprang to life and showed a sound value (my cheapo AD584 ref gives slightly less than 10 V):



I then decided to replace the original fuse holder by a 5 x 20 mm one (as I had a perfectly fitting one in my fuse holder bin). Some more checking and cleaning tomorrow. Quite content for today. 

[Specmaster]

Great sleuthing, those LCR meters are worth their weight in gold I reckon. Does you meter also measure the ESR? That's the first thing I check in preference to the capacity as I think its more of a killer then a shift in capacity, although that said of course, yours is a bit of an extreme case on that one. If it can measure ESR, I'd be curious to find out what that capacitor reads?

It looks like a great meter and maybe you might be able to find a parts mule for the other and get that working, or of course, just keep it as a parts mule for the working meter? 

[Ero-Shan]

Its a Tonghui TH2822A and does measure the ESR, of course.

https://www.eevblog.com/forum/testgear/yet-another-tonghui-th2822a-lcr-meter-review-in-pictures/

As I already said, I'm really happy with this thing. Mine never showed -2mF. I especially love it for resistor measurement (with its Kelvin clips). It is damn accurate, all the 0.1 % resistors show with less than 0.1 % deviation, and my 0.005 % one, too.

[bd139]

I use a scope and function generator to measure ESR as per the following:



Anyway I'm going to go and play with my toys now

[bitseeker]

what mechanic doesn't have a bucket of bolts under the bench; what tinkerer doesn't have bins full of leftovers and "Damifino" saved against future projects.  Not any real ones...

Yeah, they'd be called posers. 

[Cerebus]

Time for one more post before bedtime. Yes, really, this late. Surprising how far past your bedtime it can get when you're mired in LTSpice and you just can't quite figure out why your circuit design isn't quite there yet. I did get there in the end and when I looked up, "Lordy it's that late already".

Anyway, won off the EvilBay today, for the princely sum of £15 + £11 postage, a Systron Donner model 100B 10MHz pulse generator. As far as I've managed to determine so far, this beastie is of circa 1972 vintage. May or may not actually be in working condition, but I've got a manual with schematics and it's pure transistors all the way, not an IC in sight. Ought to be eminently fixable if it is DOA.

The case is showing a bad case of bromine based fire retardant ageing and the original grey now looks to be the colour of a 1970's pub toilet ceiling. You can see what I mean here (vendor's photo, cleaned up a bit):



If I'm feeling enthusiastic I may go in for trying the peroxide/UV based colour restoration - haven't decided yet.

Now I just have to sit twiddling my thumbs until it gets despatched and turns up.

[mnementh]

Took some time out this afternoon for TEA...  and a little "MacGyver-fyin'... "

I've had this beat up old Hitachi V-212 for decades; kept it in a corner hooked up to a super simple curve tracer for quick Go/No-Go testing of various components. It's had the Voltage VAR/5X Gain knob busted off the CH2 timebase since I got it; on the very rare occasion I actually needed that function on the 'scope, I just used a pliers as most of the time it was on X-Y mode anyways.

Well... As y'all know I'm hoeing out my office... and the time came this afternoon to pass final judgement on the old beast as far as "Keep or Get Rid Of". The only thing I could think of where it really shines was as a "First 'scope"; so I decided that if I could get it operating passably on all functions in an afternoon, I'd keep it for my son.

After investigating fleaBay in search of usable parts units, I found nothing I considered reasonable price for a 30-year-old 20MHz School Lab 'scope; so decided to get medieval on it's ass.




First, I put a plastic prophylactic all over the outside of the unit, since I knew I was going to be grinding and brass powder was going to go everywhere. Then I pulled out the shaft, and ground a bevel across all that was accessible using a cordless Dremel and 1/2" sanding drum.




Next, I cut apart a 4mm gold-plated banana plug to get something I could whittle down to a matching shaft diameter with a similar bevel. Resizing the shaft was done by chucking up the banana plug in a drill press then cutting it down with a cordless Dremel, then finishing with a file. Bevel was cut using cordless Dremel and same sanding drum.





[EDITED TO INTRODUCE DETAILED TECHNIQUE AND SOME COMMON SENSE]

Next, I tinned the bevel portion of original shaft and new knob; careful application of flux and working quick & hot kept solder only where I wanted it.

I'm using lead-free solder for this work; while it is harder to work with, it makes a much stronger joint in applications like this where the solder has to fill gaps. Just remember to desolder the mating surfaces clean and apply fresh flux (regular rosin flux works great) every time you make an attempt at joining the two pieces. Solder-wick clean is about right; whether you get there using solder-wick or wiping with soldering iron tip if your soldering technique is that advanced.

Then came the fun (read frustrating & repetitive) part; soldering the two together. I puttered around far too long with trying to make one of my helping hands or many vises hold the new knob just right to solder it up square & concentric and had abysmal luck.

I know, you'll probably say I'm crazy for saying this; but I've found long ago that you can get pretty damn close by feel & eyeball, as long as you can actually put fingers on the work. After dozens of attempts with vises and helping hands and holding it with hemostats, I finally gave up and did it the hard way, just like I knew I'd have to from the outset: Hold it by hand and solder it hot & quick so I could let go of it before the heat got to the part I was holding.



This method took me 3 tries before I had it nearly PERFECT.

If you don't have the correct tools (150-ish watt iron at 700 degrees F and advanced soldering skills) I recommend you do it the long hard way: Jig up the part to be repaired or use hemostats to hold the part and just be patient and willing to try dozens of times before you get it right. Your fingums will thank you for your patience.

[EDIT]




A little filing and sanding, and the shaft was repaired; then a little hot-glue inside the knob cap and pop it on while the glue's still hot...




...and it was ready for testing. I did the usual clean switches with a squirt of alcohol then dust out with compressed air; wiped down the front a little too. The bezel's been missing since I got it (well, there was a little broken piece under the CRT I took off and threw away); but for this purpose, pretty is as pretty does. If it's still humming away like this when I wake up in the morning, it'll go in the closet for future lesson time with my son.


Cheers,

mnem
*Goes to lie down before he falls down*

[tautech]

mnem
*Goes to lie down before he falls down*

And cooling fried fingers in a celebratory tipple I hope.

Nice MacGyver fix. 

[mnementh]

mnem
*Goes to lie down before he falls down*

And cooling fried fingers in a celebratory tipple I hope.

Nice MacGyver fix. 

Thanks! 

I've used this technique before to fix brass shafts; I figured this was a good place to pass on that knowledge. Sometimes you've just gotta fix what you have; replacement is not a viable option.

While I prefer to sleeve the two pieces together with brass tubing, in these multifunction switches there is rarely enough exposed brass shaft to permit that. Often I'll use brazing rod as a material source; it commonly comes in 1/16", 3/32" and 1/8" diameters. Back in the day you could still pretty easily scrounge a pot that had a brass shaft and then gut it for the splined knob hub, but those are unicorns anymore unless you get lucky on a fleaBay or DigiKey/Newark search.

No fried fingers, but that's only because I've paid the price of experience in this "Hot & Fast" soldering technique over decades; more than once I have walked around for days with a knurled pattern or the lettering from the front of a transistor melted into my fingertips from being a little too impatient and not letting the work cool down completely between attempts. THAT is what'll get you; the heat soak is MUCH faster when it has a head start.   

It DOES help (making possible for stupid hijinks like this? is that really helping?!?) that my hands have been "blessed" with thick calluses from a lifetime of hard work; first growing up on a farm (manual labor, welding and machinery repair) then working as a welder/machinist/auto mechanic, then as an appliance mechanic in later years.

Growing up in a rural community, beer and campfires/small bonfires at random places in the woods were/are a perennial thing; pretty much the only way to get out from under the eternal watchful parental gaze. One of my favorite "bar tricks" as a teenager was to light my cigarillos or someone else's with a coal from the fire; it's all a matter of timing, thick skin (literally) and not minding the smell of cooking hot dogs. 

Then I'd laugh at all the other "Manly man" boys when they had to try and wound up blowing and cursing on their fingertips. I met one girl who actually replicated the feat and we hit it off swimmingly; almost married that one. 


mnem
*Stupid Human Tricks*

[neo]

mnem
*Goes to lie down before he falls down*

And cooling fried fingers in a celebratory tipple I hope.

Nice MacGyver fix. 

Thanks! 

I've used this technique before to fix brass shafts; I figured this was a good place to pass on that knowledge. Sometimes you've just gotta fix what you have; replacement is not a viable option.

While I prefer to sleeve the two pieces together with brass tubing, in these multifunction switches there is rarely enough exposed brass shaft to permit that. Often I'll use brazing rod as a material source; it commonly comes in 1/16", 3/32" and 1/8" diameters. Back in the day you could still pretty easily scrounge a pot that had a brass shaft and then gut it for the splined knob hub, but those are unicorns anymore unless you get lucky on a fleaBay or DigiKey/Newark search.

No fried fingers, but that's only because I've paid the price of experience in this "Hot & Fast" soldering technique over decades; more than once I have walked around for days with a knurled pattern or the lettering from the front of a transistor melted into my fingertips from being a little too impatient and not letting the work cool down completely between attempts. THAT is what'll get you; the heat soak is MUCH faster when it has a head start.   

It DOES help (making possible for stupid hijinks like this? is that really helping?!?) that my hands have been "blessed" with thick calluses from a lifetime of hard work; first growing up on a farm (manual labor, welding and machinery repair) then working as a welder/machinist/auto mechanic, then as an appliance mechanic in later years.

Growing up in a rural community, beer and campfires/small bonfires at random places in the woods were/are a perennial thing; pretty much the only way to get out from under the eternal watchful parental gaze. One of my favorite "bar tricks" as a teenager was to light my cigarillos or someone else's with a coal from the fire; it's all a matter of timing, thick skin (literally) and not minding the smell of cooking hot dogs. 

Then I'd laugh at all the other "Manly man" boys when they had to try and wound up blowing and cursing on their fingertips. I met one girl who actually replicated the feat and we hit it off swimmingly; almost married that one. 


mnem
*Stupid Human Tricks*

Well if you like pyrotechnic tricks then you'll love this one... 

Make a pile of whatever you want burnt, but then top it with three layers of newspaper laid flat. Take an empty cat food can and put on the news paper four measures of gasoline using it, then stand (considerably) back, light a match and hold it to the can. Time it just right* and have just the right aim not only did you throw A LITERAL FIREBALL but you also got quite the display when it landed. 

*Failure results in a penalty of a well done hand but it always worked for me.

Not that i'd ever encourage such high-jinks and shenanigans. Don't play with matches kids! I mean it! Do what i say not what i do!

[bd139]

Nice to know there are fellow pyromaniacs on here as well ... time for photonicinduction...



Just got screwed by customs on one of my Quicko orders. £4.12 charge. Of course that's bearable for sure, but RM chucked £8 on top of that for being the monopoly of the day. Wankers!

[mnementh]

No comment, other than the fact I earned my dwagon moniker.  };=)~~~~<

The incendiary stupidity I survived as a youth should serve as a cautionary tale; let's just say I had to grow back my eyebrows a few times.   


mnem

[Specmaster]

Nice to know there are fellow pyromaniacs on here as well ... time for photonicinduction...



Just got screwed by customs on one of my Quicko orders. £4.12 charge. Of course that's bearable for sure, but RM chucked £8 on top of that for being the monopoly of the day. Wankers!

I guess it was just your turn to get screwed, customs yes, but RM, WTF?
So far I've been lucky with my Chinese stuff, its all gone through customs OK, maybe you ordered a load of stuff that get packed into one package that looked inviting? 

[bd139]

No comment, other than the fact I earned my dwagon moniker.  };=)~~~~<

The incendiary stupidity I survived as a youth should serve as a cautionary tale; let's just say I had to grow back my eyebrows a few times.   


mnem

Indeed same. One of my biggest achievements was working out that road cones could be filled up with propane.

https://youtu.be/fQB5V062_Vg

Predated the above video by a long way. Managed to nick the propane off my dad in about ‘85.

Hours of fun

[bd139]

Nice to know there are fellow pyromaniacs on here as well ... time for photonicinduction...

Just got screwed by customs on one of my Quicko orders. £4.12 charge. Of course that's bearable for sure, but RM chucked £8 on top of that for being the monopoly of the day. Wankers!

I guess it was just your turn to get screwed, customs yes, but RM, WTF?
So far I've been lucky with my Chinese stuff, its all gone through customs OK, maybe you ordered a load of stuff that get packed into one package that looked inviting?

RM default handling charge is £8. Very annoying. I think I got triggered on the HMRC database as I’ve had a crap load of stuff arrive. Probably has a “this guy looks like an importer” flag on me.

Going to pay it. What choice do I have

[mnementh]

Well... this is new.


mnem
Ow, my spleen!

[bd139]

Appears to have belonged to a Kree before.

[neo]

Recently my time has been occupied with my second hobby, but before you all forget about me and assume my commitment to the cause has faded.

https://youtu.be/VkTS9MYZLd4

I got my first server rack, very shortly thereafter i filled it from 16 and up. Yes i realize i lose some points for using half my test equipment space for audio but i should make them all back in style points 

Just to note the big CD player, i bought with a matching tape deck for a total of 50 and at the the time they were going for 750 on ebay. The tape deck you see here, i paid 5 bucks for and it's going for 100 on ebay. Always worth buying fancy stuff in person, gives you a chance to confuse the seller and then haggle.

Name the song, or at least artist, and you get a prize! _{^{prize being non material in nature}}

[tautech]

Well... this is new.


mnem
Ow, my spleen!

You are a tiger for punishment !
For years I wanted a 2465* but chickened out after reading the old thread on them here.


Fire tricks
We live rural and over the decades we've done all sorts of silly bugger things with Guy Fawkes season being a primary focus.....of course. It'd be just down right rude if you didn't. 

A couple of km down the road a family that's been there for nearly forever like ourselves used to fill biiiiiig plastic bags of those gasses commonly used in cutting torches with a 5A fuse wire connected to a long cable taped inside.
It was a cult thing for them every year and even their mum in her seventies ventured out to watch. 
Car battery for the energy source and they were good to go. 
Some years the results were better than others and they often caused a bit of a stir in the neighborhood especially with those that have horses. 
They only let one off each year and despite wanting/needing to improve on it some years you HAD to wait another 12 months for the next go. 
They had cracked it ~10 years back and for a last hurrah they used a whopper Kon Tiki balloon.......
That day I'd completely forgotten about Mr Fawkes and had just let the house in a shitty old Landrover I had back then when woooooooomph that gave me such a fright I had to return to the house for some essential toiletry and check the family was OK. F*****k it was loud, even for a couple of km away.
The wife just said 'that was a good one' and a day or so later when I caught up with our friends I checked the site.
~1m bare dirt circle surrounded by slowly heightening grass ~3m radius to natural where it was ~100mm high.

The proclaimed that after all those years of trying they'd 'finally got the brew right'. 
Sadly the Ma and oldest son are no longer with us. 

Then there was aerosols and dets........

[mnementh]

Well... this is new.


mnem
Ow, my spleen!

You are a tiger for punishment !
For years I wanted a 2465* but chickened out after reading the old thread on them here.


Fire tricks
We live rural and over the decades we've done all sorts of silly bugger things with Guy Fawkes season being a primary focus.....of course. It'd be just down right rude if you didn't. 

A couple of km down the road a family that's been there for nearly forever like ourselves used to fill biiiiiig plastic bags of those gasses commonly used in cutting torches with a 5A fuse wire connected to a long cable taped inside.
It was a cult thing for them every year and even their mum in her seventies ventured out to watch. 
Car battery for the energy source and they were good to go. 
Some years the results were better than others and they often caused a bit of a stir in the neighborhood especially with those that have horses. 
They only let one off each year and despite wanting/needing to improve on it some years you HAD to wait another 12 months for the next go. 
They had cracked it ~10 years back and for a last hurrah they used a whopper Kon Tiki balloon.......
That day I'd completely forgotten about Mr Fawkes and had just let the house in a shitty old Landrover I had back then when woooooooomph that gave me such a fright I had to return to the house for some essential toiletry and check the family was OK. F*****k it was loud, even for a couple of km away.
The wife just said 'that was a good one' and a day or so later when I caught up with our friends I checked the site.
~1m bare dirt circle surrounded by slowly heightening grass ~3m radius to natural where it was ~100mm high.

The proclaimed that after all those years of trying they'd 'finally got the brew right'. 
Sadly the Ma and oldest son are no longer with us. 

Then there was aerosols and dets........

Well, this is my Ex-NASA 2465; it was a working unit on my bench before I moved to Houston. My first guess since it's just displaying gibberish is noise from the DC-DC converter; otherwise, since it's showing video, it should post an error code for the whatever POST line item it fails at. I swapped out the one from my parts 2465, but it was old & crusty looking with leprosy-riddled caps; when I powered it up, it did nothing except whine like my 2230. The 246xx are known for failures in that DC-DC converter assembly; when I have time I'll troubleshoot for noise, but I have a living room full of storage bins right now due to the hoeing out of my office.

This is not something I need to triage right now. I'm not letting go of it no matter what, so I'm just going to reassemble it and shop for the parts to do a bulk re-cap of the converter; maybe I'll actually scope out the DC rails when I'm not so busy.

As fore fireworks... *Cue flashiebackie music*

Yeah... I remember old man Belmore; the guy who taught me welding & steel fab. One day several of my buddies and I from the junkyard were all at his shop; we were using his loading gantry to swap Bobby's wrecker bed & hoist to a new truck. Once we had it off and on the ground, we stopped for a few brews to decide what do do for lunch; while we were all standing around leaning on the old truck, Belmore comes out of the shop with an old school M-80, touches the fuse to the cigar perpetually hanging from the corner of his mouth, then sets the hissing little bomb down on one of the frame rails of the truck while we all looked on in disbelief.

"You better run." was all he said, then spun on his heel with a devilish grin and walked back into the shop.

it took half a second for what the old man had done to set in, then we all scattered like cockroaches under a just turned-on kitchen light; I made it to the end of the driveway (my grand-dad had taken me fishing with dynamite, so I knew this was gonna be loud) before it went off; even there it shocked me and my buddy Lyle.

When we went back the black sulfurous gunpowder cloud was still  hovering over the truck; it had cracked the back window in the cab and left a big black scorch ring on the frame rail with a little fist-sized dent in the middle.

"I think we need to take B to lunch for letting us use his shop." I said, walking up to the rest of Bobby's crew. Lots of nodding heads and murmured agreement followed, then before we knew it we were all on our way down to the local watering hole to get sandwiches and toddies for our bodies.

Here's tooya, B... ya crazy ol' galoot.

*Sigh*

Appears to have belonged to a Kree before.

Entirely possible; or those aliens from Independence Day. 

Fun Fact... The Kree and I have the same birthday.




Hitachi V-1100 on fleaBay

And to keep the post all TEA-Related; I stumbled across this when I was looking for pics to identify the model of my old Hitachi. Looks like it got hit in the back with the end of a forklift in a warehouse (I've seen this kind of damage before); if you get lucky and the CRT is intact, could be a nice 4-Ch scope for cheap, as it has "Make Offer" on it. [EDIT] Like a baby 2465; very similar feature set aside from being 100MHz. [/EDIT]

Cheers,


mnem
"Hold onto your butts!"

[Specmaster]

Appears to have belonged to a Kree before.

I'm just watching Star Wars for the first time but so far not seen any 2465's but lots of other strange mystical things 

Hmm, I must get myself a R2D2, great companion to have in the lab.

[bitseeker]

The case is showing a bad case of bromine based fire retardant ageing and the original grey now looks to be the colour of a 1970's pub toilet ceiling. You can see what I mean here (vendor's photo, cleaned up a bit):



If I'm feeling enthusiastic I may go in for trying the peroxide/UV based colour restoration - haven't decided yet.

I dunno. It kind of has that tan 70's look to it like that. I might just keep it as-is.