Test Equipment Anonymous (TEA) group therapy thread

[Neomys Sapiens]

What a coincidence ! I sold mine this week !!

I bought it last summer for 30 Euros and sold it for 75 Euros in less than 48 hours, I was stunned !
I mean I didn't think I would be abel to sell it at all to be honest !

Well, OK it was  not Tek it was the Createc SC-04 but... it's the OEM after all... and it's 10MHz, T202 is only 5MHz IIRC... Tek didn't sell the 10MHz version it seems (according to Tekwiki...)

Anyway, it was fun but I quickly got bored with it... just too horrible and cumbersome to use... still targeting a Tek THS 700 series as a vintage portable scope.... I saw couple here for sale at under 100 Euros, but of course they escaped me, they got sold in about 10 seconds... only to reappear a week later at 750 Euros, their usual going price over here...

Maybe it is an exhibit now at the 'musée des interfaces opérateur cruelles et idiotiques '.

[Neper]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff. 

[Vince]

The 74HC4052 MUX ICs for the Amprobe 2020 Power analyser on Tuesday. It's been a very hetic week at work so I wasn't able to look at it until yesterday. As a reminder this was a £50 ebay BIN with two sets of current clamps (200A and 1000S). It showed 0 V an all voltage inputs but current was OK. I changed both the MUX chips on the voltage inputs. That produced and output from the MUX that was missing before. Still zero on the display. I traced the circuit out through a MAX494 (quad op-amp) and MAX 492 (dual) set up for differential amp and DC offset. I then followed a live signal through to pin 97 (AN0 input) of the CPU (M30624FG). I'm strting to get worried at this point as it's an FLASH ROM CPU so no a simple replacement.
While tracing the circuit the signal also went to a LM324. Obviously not part of the voltaage measurement circuit, but I looked further. signal went to 1st op-amp configured as a unity gain buffer. The output was clipped positive but below the supply voltage. Rest of the circuit not traced but didn't seem to be doing much. As ther was a 1k resistor on the output of the buffer there was clearly something amiss. So found an old board with a SOIC LM324 and swapped it out. I was now getting a sinewave on pin 1. More interestingly I was now getting a 50 Hz squarewave on pin 8.
I don't know it it is working at this point besause you have to remove the PCB from the case to get to the component side and this disconnects the display. So put it back together, power up plug in and it works!
 
It looks like he 324 is generating a phase reference / clock and it does not measure voltage unless it's present.
Anyway een with the repair required an tidy 3 ph power anlalyser for £50 is a bargain. It has the functionality of a Fluke 43x but the build quality is way lower. It even feels light and flimsy. Good enough for my use though.

Wow well done, you didn't give up ! Glad it was something simple to repair, just cheap off the shelf parts !
You can enjoy your meter now, you worked at it, you deserve it ! 

[Vince]

What a coincidence ! I sold mine this week !!

I bought it last summer for 30 Euros and sold it for 75 Euros in less than 48 hours, I was stunned !
I mean I didn't think I would be abel to sell it at all to be honest !

Well, OK it was  not Tek it was the Createc SC-04 but... it's the OEM after all... and it's 10MHz, T202 is only 5MHz IIRC... Tek didn't sell the 10MHz version it seems (according to Tekwiki...)

Anyway, it was fun but I quickly got bored with it... just too horrible and cumbersome to use... still targeting a Tek THS 700 series as a vintage portable scope.... I saw couple here for sale at under 100 Euros, but of course they escaped me, they got sold in about 10 seconds... only to reappear a week later at 750 Euros, their usual going price over here...

Maybe it is an exhibit now at the 'musée des interfaces opérateur cruelles et idiotiques '.

Sure would be a good fit for such a museum !

I have no idea who bought it... had zero contact with the seller ! He just clicked the "buy" button, I sent the scope, got my money transferred automatically a few day later and that's it... for all I know it could have been a robot buying it, not even a human being ?! 

[WastelandTek]

I just find doing anything with gloves on is a real chore, so they only get used if there is a real health hazard.

I don't disagree...but the definition of "real" tends to move over time.  We have a strong track record of being cavalier with substances that turn out to be pretty harmful.

[mansaxel]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff.

Try insulating a house with it. Or piping. I've done both and I do not like it, even if it is quite useful, and has saved me a lot of trouble. In an attempt at being a bit English, our house has rain gutter piping that goes from the roof, through the house, and then out under it, in free air.  (The house is on plinths.) This means that the piping needs to be insulated under the house, because if it ain't the snow's going to melt on the roof, become water (duhh), keep warm through the house, and then exit under the house, in the shadow, where it will freeze solid in the piping.  Now; it doesn't, not anymore...  Thankfully enough, you can buy readymade matting of glass fibre wool with a chicken wire backing. Most useful.

[Cerebus]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff.

I think fibreglass, mineral wool, and all their cousins fall under Spec's category of genuine health hazards. Most industrial insulating materials of that ilk (e.g. for kilns and the like) have moved to 'body soluble' materials because of the potentially serious health hazards associated with having little bits of mineral fibre stuck in your skin, lungs, etc. Contact with materials of uncertain origin, like the roof insulation that someone else fitted 30 years ago, should definitely be treated as hazardous. Even the ones that are 'safer' are still irritating as hell and are best handled not with gloves, but by somebody else.

[dl6lr]

*add to cart* THANKS!
https://cpc.farnell.com/duratool/d00672/desoldering-station-uk-eu-plug/dp/SD01384

Be sure to modify the tool according to the ZD-915 thread here: https://www.eevblog.com/forum/reviews/zd-915-(ss-331)-conversion-to-24v-and-other-tweaks/

[Neomys Sapiens]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff.

I know a very effective therapy for that! I did once spend several weeks at a production plant of Rockwool(tm). After about two weeks of scratching, you care no more.

[factory]

Logic comparator says the 9312 IC (U23) removed from the A20 timebase board is dead, one of the switch inputs (pin 12) is stuck in one state.

About two weeks ago I repaired the A20 timebase board from the HP 5340A, I used the TI IC book & the 5340A manual to determine the modifications to change the pinout, turns out only three pins match between the 9312 & the 74LS151, though I missed one & it was to late to correct this once partially fitted.
It took a couple of hours with cheapo kynar mod wire, to reroute the pins to the correct holes on the board, the transplant operation was a complete success and thank you to whoever mentioned using the 74151 instead. 

And the A23 count register board is responsible for the 7s & 9s showing on the display at the same time.

Today I finally got round to working on the defective A23 count register board, now I had some replacement 74LS160 ICs for the HP 1820-0986 aka 86L75 (U2 to U7), using the logic comparator I found that all of them gave some, or many incorrect output states.



I ended up replacing all six of them and afterwards all was well & no more 7/9s showing at the same time. I also put the old ICs in the comparator and confirmed five of the six were very borked. 



The casualties from these two boards, clearly Nat Semi suck. 


David

[mnementh]

That swath of destruction smells more like PSU regulation fail or lightning damage than rando component fail... is it possible you bought a "donor" unit that was assembled at least in part out of faulty boards from other units?

mnem
 

[mnementh]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff.

I know a very effective therapy for that! I did once spend several weeks at a production plant of Rockwool(tm). After about two weeks of scratching, you care no more.

*dunks Neomys in a huge vat of calamine lotion*

There, there... the Rockwool monster isn't coming for you anymore...

mnem
*uploads pics to antisocial media*

[Specmaster]

@Vince, guess what, Dave has only gone and got himself a Fluke/Phillips combiscope, he loves it but he has a power supply issue with his and will doing a separate repair video on it later.

[Vince]

Yeah I watched the video over an hour ago when it was released ! 

I meant to post it here but I eventually decided not to...

He seems to really like it ! .. even though he really hasn't had any time to use it ! 

100 bucks for a defective 2x60MHz Combiscope is a bit expensive to me but hey, maybe they are expensive in the USA I don't know.

Got my 4x100MHz Combiscope sold untested for only 30 Euros ! And upon testing it appeared it was working perfectly !
Had I known about TEA back then, I sure could have applied for a Jammy Git award ! 

.. later I got the 4x200 model for more money, 150 Euros, but sold in working condition, so still a good deal around here.

I sure will be watching his next video about fixing it !!! 

[tautech]

Yeah I watched the video over an hour ago when it was released ! 

I meant to post it here but I eventually decided not to...

He seems to really like it ! .. even though he really hasn't had any time to use it ! 

100 bucks for a defective 2x60MHz Combiscope is a bit expensive to me but hey, maybe they are expensive in the USA I don't know.

Got my 4x100MHz Combiscope sold untested for only 30 Euros ! And upon testing it appeared it was working perfectly !
Had I known about TEA back then, I sure could have applied for a Jammy Git award ! 

.. later I got the 4x200 model for more money, 150 Euros, but sold in working condition, so still a good deal around here.

I sure will be watching his next video about fixing it !!! 

My money is on a thermal issue, maybe even something as simple as a cracked solder joint.

[Vince]

May the gods of oscilloscopes listen to you !   

I guess he could monitor the input of the HV multiplier to see if that goes bad when the problem happens.
If it does go bad then great probably means the multiplier is OK and the fault is upstream i.e. the likelihood of being able to fix it is x1000 higher !

[Neomys Sapiens]

That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky.

I'd like to add mineral wool to the list. The kind they use in loudspeakers. Makes me want to scratch myself to the moon and back if I only see the stuff.

I know a very effective therapy for that! I did once spend several weeks at a production plant of Rockwool(tm). After about two weeks of scratching, you care no more.

*dunks Neomys in a huge vat of calamine lotion*

There, there... the Rockwool monster isn't coming for you anymore...

mnem
*uploads pics to antisocial media*

Hey! That better smells good, or else..!

[tautech]

May the gods of oscilloscopes listen to you !   
I guess he could monitor the inpuit of the HV multiplier to see if that goes bad when the problem happens.
If it does go bad then great probably means the multiplier is OK and the fault is upstream i.e. the likelihood of being to fix it is x1000 higher !

Never had much good luck with that !
As you well know sometimes you really have to earn a successful repair.

Monitoring the EHT is working is darn easy with a RF loop without even a physical connection.
Let's see if Dave is prepared to show such simple tricks.

[xrunner]

The reproduction of the original Boonton 4220 setup procedures sticker is finished. I left the original sticker in-place underneath for preservation. Thanks for the tips and comments leading up to the finished product.

[Cerebus]

Hey! That better smells good, or else..!

It doesn't. When I was a kid I was forever being smothered in calamine lotion for every little injury short of anything that actually bled properly. The stuff we had was scented with the same anodyne scent that women's face powder of the time (and possibly still to this day) was scented with which I personally find revolting along with the ubiquitous, anodyne, yet still deeply penetrating scent used in baby powder.

Calamine lotion never seemed to do any good, and probably because of the similarity in name to 'camomile' and the ineffectiveness I had always assumed that it was some herbal folk remedy. I was a little surprised to discover that it was zinc oxide with a bit of ferric oxide thrown in for good measure. Confirming my childhood belief that it was about as effective as a chocolate teapot is the fact that it is actively discouraged in actual medical circles nowadays, although it is recommended to dry up weeping rashes purely on its harmless absorptive properties.

[Vince]

The reproduction of the original Boonton 4220 setup procedures sticker is finished. I left the original sticker in-place underneath for preservation. Thanks for the tips and comments leading up to the finished product.

Looks not too bad eh ! 

I do notice the addition of the spacing around " STEP " 

[xrunner]

Looks not too bad eh ! 

I do notice the addition of the spacing around " STEP " 

I wouldn't dare post the finished product without that space! 

[Neomys Sapiens]

Hey! That better smells good, or else..!

It doesn't. When I was a kid I was forever being smothered in calamine lotion for every little injury short of anything that actually bled properly. The stuff we had was scented with the same anodyne scent that women's face powder of the time (and possibly still to this day) was scented with which I personally find revolting along with the ubiquitous, anodyne, yet still deeply penetrating scent used in baby powder.

Calamine lotion never seemed to do any good, and probably because of the similarity in name to 'camomile' and the ineffectiveness I had always assumed that it was some herbal folk remedy. I was a little surprised to discover that it was zinc oxide with a bit of ferric oxide thrown in for good measure. Confirming my childhood belief that it was about as effective as a chocolate teapot is the fact that it is actively discouraged in actual medical circles nowadays, although it is recommended to dry up weeping rashes purely on its harmless absorptive properties.

Ewwww! Such a MONSTER!

[Specmaster]

Yeah I watched the video over an hour ago when it was released ! 

I meant to post it here but I eventually decided not to...

He seems to really like it ! .. even though he really hasn't had any time to use it ! 

100 bucks for a defective 2x60MHz Combiscope is a bit expensive to me but hey, maybe they are expensive in the USA I don't know.

Got my 4x100MHz Combiscope sold untested for only 30 Euros ! And upon testing it appeared it was working perfectly !
Had I known about TEA back then, I sure could have applied for a Jammy Git award ! 

.. later I got the 4x200 model for more money, 150 Euros, but sold in working condition, so still a good deal around here.

I sure will be watching his next video about fixing it !!! 

Well you really are a jammy git then, 30 Euros  , its considered to be £1 per MHz for an old CRO (2 channels) but 4 channels is something else, and then add in the digital capability and the value is again multiplied by x.

I got my 200MHz 2 channel one for £180, fully working as well, at auction a few years ago when a Philips lab in Cambridge closed down. They were fetching good money on eBay at the time, IIRC somewhere around the £500 mark.

[Vince]

Wow looks likze I finally found my bench DMM !

https://www.leboncoin.fr/equipements_industriels/2104828351.htm

A 34401A DMM for half price ?!  250 Euros ! Guy pretends it works... looks like new, it's a modern Agilent branded one, VFD looks even an bright... what's the catch ? These HP DMM/counter/DDS usually sell for twice that, 500 Euros..; or have prices plummeted recently and nobody told me ?

Maybe it's fucked .. but then same goes for all the other ones sold at 500 so...

Of course seller will say he can't test anything, no test leads etc...so won't even bother asking... but maybe if there is a self test this thing perform on its own ? A magic key combination to trigger it ? Or some menu somewhere ? I guess if tell the guy/gal what button to press, in what sequence... he could reasonably be expected to do it... maybe.

Worse case if it really is fucked and not repairable. I can just flog it on ebay and probably get my money back and some more !

Or do you sense something obviously wrong  / fishy here, am I being naïve... and I should just keep my money and add some more for more modern unit with graphical LCD that can do stats and all, like Cerebus has ??

ALSO from this seller... another item I am interested in : an electronic load. 400 Euros so quite expensive but... it's a nice TTi unit and is beefy at 400 Watts !!! 

https://www.leboncoin.fr/equipements_industriels/2102353188.htm

I vaguely researched DC loads a while back and it seems that they cost about that much money, but for Chinese stuff, and that do only 150W.
No ? So this TTi looks great value for money what do you think ? Or am I again missing something obvious here... maybe voltage range is too limited compared to modern units ? It does 80 Volts.
TTi stuff is hard to come by over here, so it's not like I can count on seeing another one of these.
Looking at the rear panel though, it's got zero options... not GPIB... no RS232, no USB no LAN no nothing... and I now realize, looking at the pic of the back of the unit, it looks like the cooling fan is missing ?!
Hmmm... this unit was messed with maybe... which means the Agilent DMM probably was too, hence why it's cheap, he is trying to flog it... am suspicious now !
Might be why it has zero I/O at the back as well... can't believe TTi would sell a fancy unit like this without ANY knd of I/O.... I bet the guy didn't just pull the cooling fan, he pulled the I/O board as well ! 
And I don't need 400 watts.... pfff.... OK, it's more reasonable to spend the money on a brand new unit, that's under warranty, more compact, "only" 150+ Watts, good enough for me, and GPIB and other I/O.... yeah.  But it sucks, because I love this generation of TTi gear, love this industrial design !

Maybe I should keep my money that I don't even have... instead of making my financial situation even much worse than it already is 


BUT IT'S TEMPTING !!!