Test Equipment Anonymous (TEA) group therapy thread

[mansaxel]

I've only ever bought one thing from Aliexpress. The $10 process calibrator discussed upthread and the subject of this

.

I did not have my hopes for getting something set very high. But Postmord (the merger of what is left of the Royal Swedish and Danish Post Offices following a large dose of NPM and general stupidity that happened to coincide with the widespread use of email and other electronic communications) actually seem to think they delivered something to my letterbox this afternoon.

I'm on my way home now, report to follow..

[Martin.M]

ebay 143407816911

I see a blue beam, location = virginia. 

[med6753]

More volt-nuttery calibrations. Today it's the Tek 2465 DMS. The DMM option. The DCV and Ohms is right on the money. No adjustments were required. ACV, on the other hand, has issues.



This is 1VAC/60Hz which is the only AC reference I have that is reasonably accurate. If you notice there are dots on the screen to the left and right of the readout. For the longest time I had no idea what those dots meant. I have since found out that it's a not well documented warning that the EAROM calibration constant data is either corrupt, missing, or out of spec. But since I don't have a full suite of ACV references I can't fix it. Which means that the ACV measurements can't be trusted. But in reality it really doesn't matter because I have other DMM's to measure ACV if required.

[mansaxel]

But Postmord (the merger of what is left of the Royal Swedish and Danish Post Offices following a large dose of NPM and general stupidity that happened to coincide with the widespread use of email and other electronic communications) actually seem to think they delivered something to my letterbox this afternoon.

I'm on my way home now, report to follow..

My mailbox was empty. Going by the amount of other peoples mail I get in my box, that probably means that a more or less decent person in this village now has my package. Some of them actually hand them over.

 

[PA0PBZ]

My mailbox was empty. Going by the amount of other peoples mail I get in my box, that probably means that a more or less decent person in this village now has my package. Some of them actually hand them over.

The other option is that they recycled a tracking # so that somebody somewhere in Sweden actually got something. If you follow the other thread you noticed that this has happened to a few others.

[worsthorse]

My mailbox was empty. Going by the amount of other peoples mail I get in my box, that probably means that a more or less decent person in this village now has my package. Some of them actually hand them over.

The other option is that they recycled a tracking # so that somebody somewhere in Sweden actually got something. If you follow the other thread you noticed that this has happened to a few others.

This is a pretty common ebay scam for stuff with unbelievable prices: vendor gets account hijacked. hijacker loads it up with lots of expensive stuff at unbelievable prices, people order and pay for stuff, get recycled tracking numbers, and wait just long enough before complaining for hijacker to move money from vendor account. vendor/ebay gets stuck with refunding. 

edit: the more nefarious version: the vendor cooperates with the "hijacker".

[Mr. Scram]

Direct question DID YOU LISTEN to the content? Show me something else factual or real world based? Repeating I once saw X or heard Y therefore it must have been true and always will be is where the issue comes from. It is like the animated  from a week ago information based on non use or dated materials or equipment as 'evidence'.

The main failures or embritelment were a Algae infused one. No one uses Algae infused PLA and single wall is what it is. I have used it a bit for lamp shades but I wouldn't try and rely on it mechanically. It is basically paper.

The sculpted one was a 3D scan failure causing a void behind the panel that came off and that print was also dropped and clearly stated unknown if the cracking was caused by that or internal failure (sample size of one). The top of that print remained intact and as printed from what I could see and most likely had some sort of UV stabilizer in the PLA?

Colour changing happens on all plastics regardless of manufacturing method and it is not a failure specific to any method.

This as I stated initially the issue there is limited real world testing of the materials or process.

My own observations of printed materials left out in the elements are real world and factual. One might argue it's anecdotal which is undeniably true but it does put to rest it being a myth or hearsay.

[bd139]

Finally got an evening off. Dug out my PA project, hooked it up to power supply, connected load, connected my norcal 40A to the input and keyed down. 1W out. Hmm. Poked around, found the SMPS module has failed ffs. Swapped it out for the meanwell one I was going to use on this anyway. Keyed down, still 1W. Hmm power supply has also failed? Can’t be possible. Then I see it. Frigging bias supply dropper zener is glowing red when I key down . Looks like it went short! 

[PA0PBZ]

Bias for class C is highly overrated anyway 

[Mr. Scram]

Now you have an optical telegraph key.

[tautech]

OXYACETELENE TORCH: Used almost entirely for lighting various flammable objects in your garage on fire. Also handy for igniting the grease inside a brake-drum you're trying to get the bearing race out of.

Never to be used inside for copper plumbing modifications without a bucket of water handy ! 

[Addicted2AnalogTek]

WIRE WHEEL: Cleans rust off old bolts and then throws them somewhere under the workbench with the speed of light. Also removes fingerprint whorls in about the time it takes you to say, "F...."

It may also zip up your shorts and cause time to freeze while you hesitate to check if you've castrated yourself...

[bd139]

Finally got an evening off. Dug out my PA project, hooked it up to power supply, connected load, connected my norcal 40A to the input and keyed down. 1W out. Hmm. Poked around, found the SMPS module has failed ffs. Swapped it out for the meanwell one I was going to use on this anyway. Keyed down, still 1W. Hmm power supply has also failed? Can’t be possible. Then I see it. Frigging bias supply dropper zener is glowing red when I key down . Looks like it went short! 

Well debugging done. That was fun.

Circuit uses a 78L09 to generate 9V from 24V to stuff across a trimmer and series resistor to bias the gate of the MOSFET. It only does this when you key down to kill idle current. As there are two PA MOSFETs independently biased, this circuit is x2. To drop some voltage and keep PD down on the 78L09's I stuffed a 5W 9.1V zener in series with both of the bias circuits. Well somewhere along the line, one of the 78L09's turned into a short to ground (cause TBD but probably me running 10W into it by accident from the K2) and when you key it it shorts the power supply to ground via the zener. This drags the power supply voltage down to about 9V which is applied to the drain of the MOSFETs. The class C bias and the low PA bias means 1W out 

Fortunately both power supplies seemed to hang up at around 2A solid which is enough to make that zener glow orange aftera few seconds but that's it. 78L09 replaced and it's done.

Had to employ the HP 6286A, 3466A and 400E for this one  .

Smells fucking awful in my living room now. That horrid burned zener smell 

[factory]

I have had Various Bridges on my evilbay list and then off again for a few years now. They are just a cool toy and nostalgic as we were made to use them in Secondary school in various forms. Do I need on absolutely not will I get on maybe 

Speaking of un needed 'toys' my Heathkit 3121 Curve Tracer turned up this morning and given it may have been made from a kit by a butcher I popped the hood for a look. Seems to have been a little rework on the board along the way as there is two fairly distinct solder looks. Overall nothing scary. Socketed IC's and some 1% resistors in the mix and when I plugged it in no smokes were released.

Very tidy overall just the knobs have a little oxidation on the inserts so I might print or cut some new ones. To repaint it in @med TEK Blue or not when it gets mounted to the stand 

Quaintly the seller included an entire CD with something on it but I will need to dig out the one PC I still own with a drive in it.

Looks like that version is just a cosmetic update of the IT-1121 which looks identical on the inside.
Mine didn't need anything doing other than both fuses replacing with the correct values.

David

I couldn't see any real difference externally or to the specs so possibly a board mod of some sort 

Had a look at this evilbay listing and whatever was done was minor I guess eBay auction: #153692048823

I didn't realize the 1121 and the 3121 are the same box... only the color and the original price were different. I just dug up schematics for both to confirm that: no difference at all.  Which is too bad because I could have picked up a 1121 cheap at Rickreall, and would have had I known. 

There was also a B+K 105A there, for 25USD, but I have one already, so I passed.

The numbers on the board in my IT-1121 match the ones in the IT-3121 beanflying has, I checked that before I posted last night, here are a couple more pictures (others here; https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1776971/#msg1776971).


David

[Terry01]

Finally got an evening off. Dug out my PA project, hooked it up to power supply, connected load, connected my norcal 40A to the input and keyed down. 1W out. Hmm. Poked around, found the SMPS module has failed ffs. Swapped it out for the meanwell one I was going to use on this anyway. Keyed down, still 1W. Hmm power supply has also failed? Can’t be possible. Then I see it. Frigging bias supply dropper zener is glowing red when I key down . Looks like it went short! 

Well debugging done. That was fun.

Circuit uses a 78L09 to generate 9V from 24V to stuff across a trimmer and series resistor to bias the gate of the MOSFET. It only does this when you key down to kill idle current. As there are two PA MOSFETs independently biased, this circuit is x2. To drop some voltage and keep PD down on the 78L09's I stuffed a 5W 9.1V zener in series with both of the bias circuits. Well somewhere along the line, one of the 78L09's turned into a short to ground (cause TBD but probably me running 10W into it by accident from the K2) and when you key it it shorts the power supply to ground via the zener. This drags the power supply voltage down to about 9V which is applied to the drain of the MOSFETs. The class C bias and the low PA bias means 1W out 

Fortunately both power supplies seemed to hang up at around 2A solid which is enough to make that zener glow orange aftera few seconds but that's it. 78L09 replaced and it's done.

Had to employ the HP 6286A, 3466A and 400E for this one  .

Smells fucking awful in my living room now. That horrid burned zener smell 

Too funny! 

[worsthorse]

It looks like I will get one good meter out of the two 8840s (more on this later).  I'd like to add the RMS VAC board, aka Option 09. The Fluke PN is 728899.  If you have this board or a scrap 8840A A/AF with this board installed that you are willing to sell, please PM or send me an email. Thanks!

[Carl_Smith]

WIRE WHEEL: Cleans rust off old bolts and then throws them somewhere under the workbench with the speed of light. Also removes fingerprint whorls in about the time it takes you to say, "F...."

It may also zip up your shorts and cause time to freeze while you hesitate to check if you've castrated yourself...

A long time ago I had long hair, and once got it caught in the chuck of an electric hand drill.  I quickly let go of the switch, but I spent that second or so while the motor coasted to a stop wondering if it was going to actually stop before it wound it's way up to the side of my head and pulled out my hair.  It did...

[Neomys Sapiens]

But Postmord (the merger of what is left of the Royal Swedish and Danish Post Offices following a large dose of NPM and general stupidity that happened to coincide with the widespread use of email and other electronic communications) actually seem to think they delivered something to my letterbox this afternoon.

I'm on my way home now, report to follow..

My mailbox was empty. Going by the amount of other peoples mail I get in my box, that probably means that a more or less decent person in this village now has my package. Some of them actually hand them over.

 

Pøstenmøpsen – the new scandinavian village game?

[beanflying]

Tripping in the big smoke. This could get expensive 

[tautech]

Bean's gone to town but will he go to town while there ? 

[Black Phoenix]

Bean's gone to town but will he go to town while there ? 

Beanflying, pack your stuff and orderly line yourself to the exit door...

[beanflying]

Single Handful of Router bits = $ 34401A 

[ArthurDent]

You seem to be on operating on an entirely different plane than I am. 

[tautech]

You seem to be on operating on an entirely different plane than I am. 

Yep, wood planes are another Rabbet (plane) hole ! 

[worsthorse]

The good news... the Fluke 8840A has a pretty impressive set of self-tests and the manual is quite detailed. The bad news... the DMM I thought had only panel problems intermittently fails the diagnostic self-tests in a way that indicates there is a PSU problem, which would be okay because I can fix that, but the power supply readings are all good. Now the self-test failures could be caused by a keypad problem but that seems unlikely, so tomorrow I start probing around to see if I can find an intermittent component.

Scratching my head and wondering where I stashed the freeze spray.

And... the Tek parts guy sent me the wrong transistors, so I can't finish fixing the signal gen tonight either. 

So away from the bench I go to read some more of Michael Faraday's biography.