Test Equipment Anonymous (TEA) group therapy thread

[nctnico]

At least there’s no ticks, snakes or crocodiles in those rows of houses

I got snakes, coyotes, armadillos, possums, porcupines, deer, rabbits, bobcats and someother, larger form of mountain cat. Supposedly if you go deep enough even wolves and maybe a bear.

With the exception of wolves and bears I've seen all those personally.

Interestingly enough i have a half bobcat half house cat hybrid as a pet who i call garfield

There you go, another advantage you have over us Brits, your very own zoo 

There can be lots of wildlife near big cities too. Besides lots of different kind of birds I have seen rabbits, deer, a fox and traces of beaver activity only a short bike ride away. Not to mention horses and cows which roam freely in certain areas. Because there are so many people as well and there is no hunting most of these animals aren't very shy.

[bd139]

We've got parrots living in the trees behind my house. It's amazing what you see in cities. I assume they are escaped pets.

Well at last Ebay is picking up, got 5 things again on my watch list, lets see what I end up with, not going to say what I'm watching or where incase it puts the mockers on it, don't want to be paying stupid money which is what tends to happen if your not to careful and caught up in the adrenaline rush at the auction closing stages.

Indeed. Got a couple of things myself. Hopefully no overlaps between you and me

Just got a whoooole load of crap from China arrive so I'm busy actually using my test gear to blow it all up now. Quite impressed. Bought a £0.99 boost converter and I can't kill it. I can usually kill anything in a few minutes.

[Specmaster]

We've got parrots living in the trees behind my house. It's amazing what you see in cities. I assume they are escaped pets.

Well at last Ebay is picking up, got 5 things again on my watch list, lets see what I end up with, not going to say what I'm watching or where incase it puts the mockers on it, don't want to be paying stupid money which is what tends to happen if your not to careful and caught up in the adrenaline rush at the auction closing stages.

Indeed. Got a couple of things myself. Hopefully no overlaps between you and me

Just got a whoooole load of crap from China arrive so I'm busy actually using my test gear to blow it all up now. Quite impressed. Bought a £0.99 boost converter and I can't kill it. I can usually kill anything in a few minutes.

If we are overlapping and you win, thats fine, I respect you so I can live with that, anyone else though 

Whats the point in buying stuff to blow shit out of it? 

[bd139]

I'm only semi-serious. I'm testing the design limits of very cheap switching converter ICs. I'm interested to see how they perform thermally, efficiency-wise, reliability-wise and noise-wise in extreme conditions. So far, not bad.

I've got a little 12v@500mA module I'm driving very hard at the moment about 50% over it's rated input current by running it under voltage. It's getting a blast of a hair dryer whilst doing its thing. 6W out, 8W in, 2W being burned off at about 80oC at the moment. It's getting so hot the shitty disposable breadboard I'm using is starting to actually melt. Noise is a bit naff at 200mV spikes. Getting rid of those with a pi filter. All good so far 

If it works for this, I'm good to buy some more and run them half load.

[Specmaster]

I agree, why reinvent the wheel if someones already done it and it performs well, unless of course you can make it better.

[bd139]

Well the trick is to find an established design, test it and then rip it off for your own product 

(yes I'm ripping off China for a change)

[tggzzz]

Well the trick is to find an established design, test it and then rip it off for your own product 

Old aphorism, that used to be drummed into engineers, but which seems to be forgotten: "you can't test quality into a product".

Testing merely demonstrates you haven't found a problem - yet.

Of course in the good old days, PSUs were a standard failure mode simply because the experienced engineers handed off that boring topic to the new inexperienced engineers.

[bd139]

This is very true.

The objective here is to meet a price point, so starting with people who know how to build stuff to a price point makes sense

I would love to stick a TI simple switcher in this but the BOM cost is too high.

[mnementh]

Nice "power conditioner."

Sometimes Too Much is exactly the right amount.

Indeed. Same.

I tend to, and this is shockingly bad to some, actually drill another hole in the board if it's possible to do so and then use a radial and glue it down. You can see a couple of unglued ones here I did in a Heathkit counter (FML that was totalled by the previous owner - I had to build an entirely new timebase for it):



If it's point to point wired, you're screwed

It's only ugly until you put the cover back on 'er, buddy. 

I'm only semi-serious. I'm testing the design limits of very cheap switching converter ICs. I'm interested to see how they perform thermally, efficiency-wise, reliability-wise and noise-wise in extreme conditions. So far, not bad.

I've got a little 12v@500mA module I'm driving very hard at the moment about 50% over it's rated input current by running it under voltage. It's getting a blast of a hair dryer whilst doing its thing. 6W out, 8W in, 2W being burned off at about 80oC at the moment. It's getting so hot the shitty disposable breadboard I'm using is starting to actually melt. Noise is a bit naff at 200mV spikes. Getting rid of those with a pi filter. All good so far 

If it works for this, I'm good to buy some more and run them half load.

There are cheap China-direct DC-Dc converters of all kinds available now for a buck or three a copy; Buck, Boost, Buck/Boost, many with CC/CV available to boot. Between those and the commodity BMS boards also available cheap as beans, reliable Lixx power for almost anything is available for a few $$ with off-the-shelf components.

One of my favorites for hobbyist work is the D-Sun Mini-360; costs ~50¢ each in qty 10, has excellent efficiency, very clean output for a switcher and a solid 1.5A output with 5-23V in/1-18V out range makes it very versatile. Add an electrolytic at each end and output is as clean as almost any linear, and the voltage adjustment trimpot is single-tap, so making it fixed is as easy as unsoldering the trimpot and soldering in an appropriate SMD resistor.

Right now I have about 4 projects in the works with these cheap CC/CV regulators driving high-powered COB LED lighting; they're just like Legos for electronics tinkering.

I picked up one of these a while back because it saved me 25% on my order; still haven't figured out what I'm gonna use it for, but having that kind of power on hand for automotive/portable projects is just viscerally satisfying.


mnem
*Modular brain*

[Ero-Shan]

Welp... they delivered my AD584 voltage reference from eBay while I was away visiting family over Thanksgiving; now that I'm back, I finally have a little time for puttering on the bench. I got lucky and what was delivered is actually an AD584LH version, so quite pleased to get it for $7 even with the wait.

At first I intended to just cut off the part of the board with that stupid 15V battery connector, but then I found this ridiculously overkill filter cap rattling around the bottom of my parts drawer that just had to go in that hole. A little circuit rework to add a 10 ohm resistor to act as a basic fuse and to prevent inrush current from smoking the RPP diode, then a 1500 ohm bleeder and now I'm happy. The cap charges in about a second and discharges in about 10 seconds, so I'm pretty certain I won't have to worry about fluctuations caused by poor contact in the coax power connector, plus I can power it using a cable I already had made up for one of my LiPo chargers.

Since this was recommended to me buy you folks, I also ordered one, due to arrive anytime between next week and mid of January. With my kind of luck, there's not much hopes to get an 'L', too, though.
But thanks for the nice supply idea ... I'd have likely omitted RPP diode and bleeder.

[mnementh]

Welp... they delivered my AD584 voltage reference from eBay while I was away visiting family over Thanksgiving; now that I'm back, I finally have a little time for puttering on the bench. I got lucky and what was delivered is actually an AD584LH version, so quite pleased to get it for $7 even with the wait.

At first I intended to just cut off the part of the board with that stupid 15V battery connector, but then I found this ridiculously overkill filter cap rattling around the bottom of my parts drawer that just had to go in that hole. A little circuit rework to add a 10 ohm resistor to act as a basic fuse and to prevent inrush current from smoking the RPP diode, then a 1500 ohm bleeder and now I'm happy. The cap charges in about a second and discharges in about 10 seconds, so I'm pretty certain I won't have to worry about fluctuations caused by poor contact in the coax power connector, plus I can power it using a cable I already had made up for one of my LiPo chargers.

Since this was recommended to me buy you folks, I also ordered one, due to arrive anytime between next week and mid of January. With my kind of luck, there's not much hopes to get an 'L', too, though.
But thanks for the nice supply idea ... I'd have likely omitted RPP diode and bleeder.

It's not a matter of needing this level of absolute accuracy; it's a matter of having something you know is close enough to the absolute standard to be sure your own gear isn't totally out to lunch, or at least for me that's the case anyways. Most everything I work with anymore are relatively simple digital projects; STM32 and occasionally Atmel 8-bit, so anything more than 3 digit accuracy is pretty much unnecessary.

Actually, the RPP series Diodes are part of the original design; this model has them on both the BATT and Coax Power circuits. I just massaged the existing design a little. 


mnem
*Rare moment of pragmatism*

[tggzzz]

It's not a matter of needing this level of absolute accuracy; it's a matter of having something you know is close enough to the absolute standard to be sure your own gear isn't totally out to lunch, or at least for me that's the case anyways.

*Rare moment of pragmatism*

Heretic and heresy, respectively.

[neo]

I've found this numerous times as well. The old Philips axial electrolytics had much longer leads than they do now under the Vishay/BC brand. I bought some old ones a few years ago for a refurb and they were about 3 inches long on each end!

I don't like extending the leads if I can avoid it, it adds another future potential problem with bad joints.

Sent from my SM-J510FN using Tapatalk

On a fair few of these caps i had literally no choice. I at least got the values exactly right even if it did mean paralleling capacitors. After this i am sure of one thing, If Mr.Carlson doesn't spend a fortune in all these parts that make it look easy  then he must either know a guy or buys it in massive bulk.

[neo]

OK something odd happened, the thing did and still does work but an adjustment for beam shape, a potentiometer, popped and i think sparked when i adjusted it, or tried to.

Also:

The intensity control/power switch works fine if i spray it with contact cleaner but later when it dries it gets so jammed up it can't move at all, any reasonable fix other than replacement?

When i adjust the vertical gain i can hear a tube ringing or something of the like.

Did i screw up on the filtering caps? I'm at least 90% sure i got the wires where they were supposed to be.

[Specmaster]

OK something odd happened, the thing did and still does work but an adjustment for beam shape, a potentiometer, popped and i think sparked when i adjusted it, or tried to.

Also the intensity control/power switch works fine if i spray it with contact cleaner but later when it dries it gets so jammed up it can't move at all, any reasonable fix other than replacement?

Its clearly in need of some lubrication, try a little light oil, something "3 in 1" if you have that over the pond, or a drop of "WD-40" but not from an aerosol can, a few drips on the end of a screwdriver or similar and applied to the metal parts where its metal on metal friction and then work it in, after leaving it a few minutes to penetrate into the bearing surfaces.

[neo]

I can get 3 in 1 oil and i will try it for the inten control but that does not answer the question as to why the spot shape adjustment sparks and why, when on ext input, the dot does weird things? 

[mnementh]

It's not a matter of needing this level of absolute accuracy; it's a matter of having something you know is close enough to the absolute standard to be sure your own gear isn't totally out to lunch, or at least for me that's the case anyways.

*Rare moment of pragmatism*

Heretic and heresy, respectively.

You're welcome.


mnem
Clothes make the man, but they won't make you breakfast in the morning.

[Specmaster]

OK something odd happened, the thing did and still does work but an adjustment for beam shape, a potentiometer, popped and i think sparked when i adjusted it, or tried to.

When i adjust the vertical gain i can hear a tube ringing or something of the like.

Did i screw up on the filtering caps? I'm at least 90% sure i got the wires where they were supposed to be.

OK then, you're clearly working on a scope, what one is that? I take it from what your're saying that you have been recapping it? The thing when recapping is to do them one at a time to ensure that you do get them connected correctly. The smoothing caps will be electrolytic and they will have the negative clearly marked but tants can be marked in a variety of ways and the best way to work out which is which is to google for the connections on them.

Now I would not think that if you did one with the polarity reversed you would get the issues you mentioned, they would normally in my experience blow up if reversed. So at the moment I'm stumped for any ideas, perhaps if bd139 is on line and reads this he might have some ideas, especially if your working on a tektronix scope.

In the meantime, if these problems have only occured since you started working on the caps, I'd retrace your steps and double check what you've done, maybe you disturbed something by accident when extracting a cap, or you may have made a solder bridge somewhere when soldering in the new caps?

[VK5RC]

A new addition to the LED love-fest, a 3466A, batteries dead of course but replaced with eneloops easily. All working - within specs. Quick outside clean up.
One of the most unusual voltage setting systems - select 2 or 3 of 5 resistors for the 4 voltage settings.

[Cerebus]

..., try a little light oil, something "3 in 1" if you have that over the pond, ...

Sewing machine oil works well too and is often something that's already in the house.

[Specmaster]

They are a nice meter, my battery was dead too, I sourced another with slightly different terminal arrangements, slightly smaller in physical size so packed it out with some bubble wrap to ensure I did not squeeze the battery to make it leak, all working pretty good. Meter also is fully up to specs and is very well made, very pleased with it. The only downside is that compared with more modern meters, it is relatively slow in ranging, but it is certainly livable with, I love it.    

[neo]

OK something odd happened, the thing did and still does work but an adjustment for beam shape, a potentiometer, popped and i think sparked when i adjusted it, or tried to.

When i adjust the vertical gain i can hear a tube ringing or something of the like.

Did i screw up on the filtering caps? I'm at least 90% sure i got the wires where they were supposed to be.

OK then, you're clearly working on a scope, what one is that? I take it from what your're saying that you have been recapping it? The thing when recapping is to do them one at a time to ensure that you do get them connected correctly. The smoothing caps will be electrolytic and they will have the negative clearly marked but tants can be marked in a variety of ways and the best way to work out which is which is to google for the connections on them.

Now I would not think that if you did one with the polarity reversed you would get the issues you mentioned, they would normally in my experience blow up if reversed. So at the moment I'm stumped for any ideas, perhaps if bd139 is on line and reads this he might have some ideas, especially if your working on a tektronix scope.

In the meantime, if these problems have only occured since you started working on the caps, I'd retrace your steps and double check what you've done, maybe you disturbed something by accident when extracting a cap, or you may have made a solder bridge somewhere when soldering in the new caps?

Heathkit 0-12 as i mentioned at the end of page 170. Retracing isn't so easy because, and this is the main reason i am not 100% sure i got it right, there are three grey wires and their location is not exactly clear.

I know where one belong and then using the markings on the circuit board they go to, and basing my guesses on that one wire, i am able to figure out the others. The entire reason i couldn't do one at a time is i need the old one out so that i had room to work.

Also contributing to my confusion is that if i got a wire crossed i would expect it not to be able to function at all except as it is it functions fine till you try the spot adjust, just having it set to EXT. horizontal input causes the dot to do odd things.

[Specmaster]

Have you got yourself a service manual to work from?

[neo]

Have you got yourself a service manual to work from?

Not quite a service manual but a schematic and parts list. As well as the steps to properly adjust it, and this https://www.youtube.com/watch?v=RF7CRqb54XM.

Edit, My problem is that i don't even know what my problem is, all I've done yet is solid state but i would assume if i had a hundred volts or so extra going where it shouldn't all hell would break loose. 

[Specmaster]

In that case you should be able to trace those wires from A to B and reconnect them to their correct locations. There's nothing to that scope is there, its very spartan