Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

For those of you wondering why I didn't use many of suggestions for finding this shorted tant on the 485 let me give you a quick synopsis as to why:

1. I don't own any thermal imaging devices.

2. None of my power supplies have current limiting. So if it WAS a board short I ran the risk of burning the board and permanently damaging it.

3. There is NO WAY in hell am I EVER going to use lighter fluid on a circuit board.  That is just plain dumb and I don't care who's done it. They are asking for trouble. Besides, I don't have any.

4. Having a schematic that matched the board would have cut the troubleshooting time. Seems I run into this often because Tek is always making updates and improvements during a product run.

Yes, it was also a good reason to spare you the hint that a board like yours seemed to be the perfect application for the GenRad GR2220 BugHound, as you would have surely used it if you had one.

Hmmm... interesting alternative to the ShortSqweek I was "missing out loud" a little earlier.    10mA applied should be harmless in most cases; particularly to a power rail.

The 2220 is on page 162 of this PDF catalog. A really grainy PDF of the UM is here.

mnem
*Tinker-ily*

[Specmaster]

For those of you wondering why I didn't use many of suggestions for finding this shorted tant on the 485 let me give you a quick synopsis as to why:

1. I don't own any thermal imaging devices.

2. None of my power supplies have current limiting. So if it WAS a board short I ran the risk of burning the board and permanently damaging it.

3. There is NO WAY in hell am I EVER going to use lighter fluid on a circuit board.  That is just plain dumb and I don't care who's done it. They are asking for trouble. Besides, I don't have any.

4. Having a schematic that matched the board would have cut the troubleshooting time. Seems I run into this often because Tek is always making updates and improvements during a product run.

Yes, it was also a good reason to spare you the hint that a board like yours seemed to be the perfect application for the GenRad GR2220 BugHound, as you would have surely used it if you had one.

Hmmm... interesting alternative to the ShortSqweek I was "missing out loud" a little earlier.    10mA applied should be harmless in most cases; particularly to a power rail.

The 2220 is on page 162 of this PDF catalog. A really grainy PDF of the UM is here.

mnem
*Tinker-ily*

Way ahead of you, already downloaded and that does look like a really useful piece of kit to have.

[Specmaster]

I’ve been on fire a couple of times worse than that for ref. It looks pretty bad but nothing to worry about mostly. As long as you put it out quick. Most injuries from chemical fires only happen due to the panic when something goes woosh which makes the problem 10x worse.

IPA is pretty nasty stuff if it goes up. Can’t see the flames and the vapour settles on surfaces. You don’t know it’s on fire until your skin starts peeling off or you feel the heat from a distance. Flash point is pretty low too.

Yep, flash point on IPA is as low as 12C or 53F under the right conditions, Zippo is around 100F and as you rightly said, flames are visible. Both can nasty stuff, but just the fumes of IPA are bad and can toxic in unventilated area and care should be taken to avoid skin contact as well.

[mnementh]

Zippo fumes are from naphtha and mineral spirits, and known carcinogenic as well as capable of burning mucous membranes just from inhalation. The naphtha also has a very low flashover point when in process of evaporation, just like pure alcohol. Both are EXACTLY the situation we're discussing using them in. If you've ever tried to fill a Zippo with alcohol, you know it won't light unless you do what that arsehole in the video did: spill it all over from hell to breakfast. It evaporate too fast from a small wick to produce sufficient fuel/air ratio.

Meanwhile, 91% alcohol is much more stable, cuts some things pure alcohol will not, and it's primary daily use hazard is contact with skin causing dehydration dermatitis.

mnem
Also cute and fluffy!!! 

[Kosmic]

Naaahh I'm telling you, the way to do it is with freeze spray. Not IPA nor lighter fuel. 

[mnementh]

Ooohhh... another trove of manuals. Amazing what you find when look up one level in a random link... 

http://exodus.poly.edu/~kurt/manuals/manuals/Other/

bitseeker, another one for the resources list. 

mnem
Weeth seex joo get egg loll.

[mnementh]

psssst... those of you who were liking Cerebus' 3616A PSU a while back... eBay auction: #333286184007

mnem
sssh...

[mnementh]

Yeah, that's where I was suggesting bitseeker put this link. I knew he knew where it was, but I evidently just kept looking right over it myself.

 But... it appears kurt's little trove is already there; line item ummmm... number 18 on tautech's list.

Nevermind. 

mnem
Doyt!

[TiN]

Broken Agilent 33522B bought and paid. Whelp. 

[Carl_Smith]

Bitch Lives.

Woah! Post-ception in that post and its pic.

[Kosmic]

Broken Agilent 33522B bought and paid. Whelp. 

Look like a fine AWG hope you will be able to fix it !

[Carl_Smith]

I'd really rather put that money towards a Sabrent Rocket nvme4.0 drive before the word gets out, though. 4500/5500 MBps in the 1TB size for $199.

[mnementh]

Broken Agilent 33522B bought and paid. Whelp. 

Considering I just rejected a $50 counteroffer on a as-is FY6800, I'm afraid to ask what you paid for THAT as-is... 

mnem
Better not say; you'll jinx it.

[worsthorse]

Yep. When I was a kid we had zippos. None of us smoked. Usually for casual arson  . Deadly dangerous things.

Holy shit....now THAT's dumbass.  Darwin almost caught him. 

Seriously?  I think it is a pretty safe bet that his life expectancy is shorter than average.

[worsthorse]

For those of you wondering why I didn't use many of suggestions for finding this shorted tant on the 485 let me give you a quick synopsis as to why:

1. I don't own any thermal imaging devices.

2. None of my power supplies have current limiting. So if it WAS a board short I ran the risk of burning the board and permanently damaging it.

3. There is NO WAY in hell am I EVER going to use lighter fluid on a circuit board.  That is just plain dumb and I don't care who's done it. They are asking for trouble. Besides, I don't have any.

4. Having a schematic that matched the board would have cut the troubleshooting time. Seems I run into this often because Tek is always making updates and improvements during a product run.

Yes, it was also a good reason to spare you the hint that a board like yours seemed to be the perfect application for the GenRad GR2220 BugHound, as you would have surely used it if you had one.

Hmmm... interesting alternative to the ShortSqweek I was "missing out loud" a little earlier.    10mA applied should be harmless in most cases; particularly to a power rail.

The 2220 is on page 162 of this PDF catalog. A really grainy PDF of the UM is here.

mnem
*Tinker-ily*

Way ahead of you, already downloaded and that does look like a really useful piece of kit to have.

Jim Williams offered a circuit for short hunting in one of the analog design books, probably Troubleshooting Analog Circuits. I will dig it up later and see if I can find the reference. It looked worth having around.

[worsthorse]

I exchanged emails with the shop that sold me the 485. I described the two issues and they offered to refund my shipping costs, which brings the cost of the scope down to 100USD.  Good enough for me.  What's the worst that can happen? I fubar rather than fix it and am out a hundred bucks. If that happens, I still have a parts mule, or can use it for capacitor removal practice. 

In other TEA news, the capacitors for the 501A arrived today and I spent a couple of hours replacing two big electrolytics, three small ones and a couple of questionable polys. One each of the big and small electrolytics were bad. When I powered it up, the noise was gone. The step waveform (that drives the base) is clean. The collector sweep (which is basically the full wave rectified line voltage) still isn't quite symmetrical but I suspect that's a design problem. 

One weird thing. The electrolytics were all installed with RTV compound between the board and the capacitor. The caps look like replacements, so I am guessing someone glued them down to hold them in place while soldering. 

Quick check out suggests that I didn't install any electrolytics backwards.    Will recalibrate and reassemble it tomorrow; probably photos to follow.

[0culus]

For those of you wondering why I didn't use many of suggestions for finding this shorted tant on the 485 let me give you a quick synopsis as to why:

1. I don't own any thermal imaging devices.

2. None of my power supplies have current limiting. So if it WAS a board short I ran the risk of burning the board and permanently damaging it.

3. There is NO WAY in hell am I EVER going to use lighter fluid on a circuit board.  That is just plain dumb and I don't care who's done it. They are asking for trouble. Besides, I don't have any.

4. Having a schematic that matched the board would have cut the troubleshooting time. Seems I run into this often because Tek is always making updates and improvements during a product run.

Yes, it was also a good reason to spare you the hint that a board like yours seemed to be the perfect application for the GenRad GR2220 BugHound, as you would have surely used it if you had one.

Hmmm... interesting alternative to the ShortSqweek I was "missing out loud" a little earlier.    10mA applied should be harmless in most cases; particularly to a power rail.

The 2220 is on page 162 of this PDF catalog. A really grainy PDF of the UM is here.

mnem
*Tinker-ily*

Way ahead of you, already downloaded and that does look like a really useful piece of kit to have.

Jim Williams offered a circuit for short hunting in one of the analog design books, probably Troubleshooting Analog Circuits. I will dig it up later and see if I can find the reference. It looked worth having around.

I thought that was Bob Pease?

[0culus]

snip

One weird thing. The electrolytics were all installed with RTV compound between the board and the capacitor. The caps look like replacements, so I am guessing someone glued them down to hold them in place while soldering. 

Quick check out suggests that I didn't install any electrolytics backwards.    Will recalibrate and reassemble it tomorrow; probably photos to follow.

Wow...seriously there are way easier techniques for getting components in place without resorting to glue.  Looking forward to pics!

[worsthorse]

Jim Williams offered a circuit for short hunting in one of the analog design books, probably Troubleshooting Analog Circuits. I will dig it up later and see if I can find the reference. It looked worth having around.

I thought that was Bob Pease?

You are right. It was. I mixed it up with Williams' Analog Circuit Design. 

[mnementh]

Yeah; IIRC, you're talking about the low-current (relatively) impedance-reactive oscillator circuit on which the ShortSqweek was based. It was a Nuts/Volts article that became a product for a while.

mnem
*toddling off to ded*

[BU508A]

Yesterday evening, when it was late and I was tired, I was confused all about this different liquids.

I have made here a little list, just to clarify (to myself    )

In Germany, there is a thing which we are calling "Feuerzeugbenzin", which is this in english:
https://en.wikipedia.org/wiki/Ligroin
I would not use this stuff for cleaning anything.

But there is another thing, which we are calling "Wundbenzin", which is in english:
https://en.wikipedia.org/wiki/Petroleum_ether
And this stuff I'm using occasionly as a cleaning solvent.

And somehow I've mixed all this stuff with "Flüssiggas" or "Feuerzeuggas", which is in english:
https://en.wikipedia.org/wiki/Liquefied_petroleum_gas
Maybe this will use some hobos as a "cheap" alternative to find thermal issues.
Which is, imo, a very bad idea.
I've read about people which using this stuff to extract THC and their distillator exploded.  What a surprise. 

And,  when I'm going to use IPA I mostly use small amounts of them in a good ventilated enviroment
and I make always sure, that the bottle is closed after getting some IPA.

Edit:
Just for completeness: IPA
https://en.wikipedia.org/wiki/Isopropyl_alcohol

[mnementh]

Liquified Petroleum Gas must be stored under pressure, as it boils away instantly at room temperature/atmospheric pressure. While this would make it possible to use as a freezing agent, it would also make the local atmosphere highly explosive. 

The "canned air" freeze spray mentioned earlier is pressurized fractioned air. Mostly nitrogen gas and whatever trace gases are not easily fractioned out mechanically; a small portion of which will liquefy under pressure in a spray can. If triggered while inverted, the can will spray that liquefied nitrogen at a target PCB; which if heated by a short, will quickly show in the frost traces. This is what we were discussing. 

I mentioned naphtha (ligroin) because it a component of Zippo and BBQ Starter Fuels; its high volatility and flammability make it an excellent ignition aid/accelerant for less volatile mineral spirits which comprise the main content of these fuels. Naphtha can burn your nose and lungs if allowed to evaporate quickly over a large area (the exact application being discussed); the mineral spirits will stink up your workbench for days. 

Never heard of any of these being used to extract TetraHydroCannabinol; the active ingredient in marijuana... but with these "synthetic THC" products I've seen flourishing over the last decade or so I'm sure it's possible. Much more common horror stories involve LPG being used in distillery processing for crystal meth.

mnem
grr. arrg. coffee-deprived zombie-dwagon...

[med6753]

The other day I mentioned I had another small wood working project on tap. Well, here it is...ready for stain and poly. It is TEA related. If you can guess what it's for you will be granted genius of the day. Guess wrong and there's no penalty.

Once it's done I will reveal it's purpose.

[bd139]

Smells like a scope clock

[worsthorse]

The other day I mentioned I had another small wood working project on tap. Well, here it is...ready for stain and poly. It is TEA related. If you can guess what it's for you will be granted genius of the day. Guess wrong and there's no penalty.

Once it's done I will reveal it's purpose.

It is for holding scope CRTs.

Sending my trophy USPS mail is completely okay.