Test Equipment Anonymous (TEA) group therapy thread

[TERRA Operative]

Well, a Croatian friend here in Japan talks about driving from there to here, with the only real sea crossing being from Korea that can be done by boat, oh and the Adriatic Sea when you are heading out of Italy, but just bring a canoe.
Apparently the Asian Highway 1 connects to the European route E80, so you can drive from over your way all the way to Tokyo.

I'll meet you at Tokyo Station, call me when you are near. Good luck! Haha 

[Vince]

Wow your friend is well motivated ! 

As for me, my right foo and knee and leg hurt very badly after 45 minutes of driving or so... so... going to Japan is not possible  ! 
Plus, petrol is so expensive, not to mention the cost of maintenance with all those kilometers that... it's 100% certain that even a business class flight would be much less expensive ! 

Luckily internet and TEA exist to keep people in touch from all over the world for next to nothing !

[Vince]

Best you can do is recharge at C/10 nd see what happens.
Unfortunatly discharging it to flat is not the same as it self-discharging it to flat. Self dischrg  happens to each cell independently. A discharge through an external circuit causes the first cell(s) to reach 0 V to be charged in reverse by the discharg current from the other cells flowing through them.  Thi can damge the cells.

Ah well... not too worried given the price of a new battery if I ever need to use one. I am just having a bit of fun here of course, it's for educational purposes mostly... 

So let's recharge it slowly and see how it goes... nothing to lose eh... it's 30 years old, I had zero expectations about it from the get go anyway ! 

Stay tuned...

[TERRA Operative]

Wow your friend is well motivated ! 

As for me, my right foo and knee and leg hurt very badly after 45 minutes of driving or so... so... going to Japan is not possible  ! 
Plus, petrol is so expensive, not to mention the cost of maintenance with all those kilometers that... it's 100% certain that even a business class flight would be much less expensive ! 

Luckily internet and TEA exist to keep people in touch from all over the world for next to nothing !

What's a quick 53,000km trip anyway? Barely a trip down to the shops! Hahahaha

[ch_scr]

Fun with TE today:
Compare Jitter of two OCXO. Yesterday, to compare results with DMTD,
Cycle-to-Cycle phase difference between two OCXO was plotted on scope:

Now that does not look right, jitter should be random not periodic 
Because this is a comparison measurement, how to be sure,
what to make of it, maybe even a sampling artifact? Today it dawned on me:
Now with third OCXO, one can do another comparison and figure out the culprit!

Now that looks more like expected!
Culprit is found in either OCXO or it's surrounding circuit 
Now to dig there further 
Edit: Also, I want to add that this specific function - to plot a measured value as a trace -
is what makes a "professional grade" DSO for me. You sure do not need it often,
but IF it's a godsend...

[mnementh]

not a test equipment. but long days ahead of repairing this gear.

Mmmmhmmm... so why are we socketing those epoxy-bombs? Are they a high-failure device, or is it so you can swap them around for comparison troubleshooting?

Good old-school desoldering technique; if you do a lot of this kind of desoldering work, a hot-air rework station can really improve your quality of work and save time/consumables as well. 

I have to admit I cringed a little when I saw you only tack one leg down on the new socket. I'll usually tack one leg at each end while applying pressure from the top side to ensure the socket is tight-tight against the board. I've broken solder pads off/vias out when plugging in a device because I didn't do that. 

Also, I try to alternate soldering pins as far away from each other as possible, rather than going down the line from one to the next, especially if working on old Paxolin PCB. This limits heat applied in the same area of the board all at once, and reduces likelihood of delaminating a pad/trace.

Obviously this is not a "You must do this!" thing; just passing on technique I've learned over the years from fuxxoring things up and having to make ugly repairs.

Good work and we look forward to the next installment! 

mnem
 

[Martin Miranda]

so why are we socketing those epoxy-bombs? Are they a high-failure device, or is it so you can swap them around for comparison troubleshooting?

  yes, and turns out, only 1 remaining module works. 

Also, I try to alternate soldering pins as far away from each other as possible, rather than going down the line from one to the next, especially if working on old Paxolin PCB. This limits heat applied in the same area of the board all at once, and reduces likelihood of delaminating a pad/trace.

  took me a whole day slowly desoldering the damn thing. hahaha. i don't even want the solder mask scratched! but i have all the time for this to get repaired anyways. 

adding sockets to the battery, recapping and converting to 220vac.  it's noisy and detuned.

[Specmaster]

not a test equipment. but long days ahead of repairing this gear.

I think he needs a desoldering tool, using wick like that takes a long time, just a few seconds with a proper tool.

[ch_scr]

so why are we socketing those epoxy-bombs? Are they a high-failure device, or is it so you can swap them around for comparison troubleshooting?

  yes, and turns out, only 1 remaining module works. 

Also, I try to alternate soldering pins as far away from each other as possible, rather than going down the line from one to the next, especially if working on old Paxolin PCB. This limits heat applied in the same area of the board all at once, and reduces likelihood of delaminating a pad/trace.

  took me a whole day slowly desoldering the damn thing. hahaha. i don't even want the solder mask scratched! but i have all the time for this to get repaired anyways. 

adding sockets to the battery, recapping and converting to 220vac.  it's noisy and detuned.

If you do a lot of through hole desoldering, this (or something comperable) will make youre life sooo much easier. It's so much faster than desolder braid.

[Specmaster]

Wow your friend is well motivated ! 

As for me, my right foo and knee and leg hurt very badly after 45 minutes of driving or so... so... going to Japan is not possible  ! 
Plus, petrol is so expensive, not to mention the cost of maintenance with all those kilometers that... it's 100% certain that even a business class flight would be much less expensive ! 

Luckily internet and TEA exist to keep people in touch from all over the world for next to nothing !

Yep, I get the same issues with my right knee after a spell of driving, even with the cruise control on. I think it is more related to the pedals position in relation to the seat. On most cars, the pedals are slightly offset due to the wheel well intruding into the interior space too much.

[Martin Miranda]

I think he needs a desoldering tool, using wick like that takes a long time, just a few seconds with a proper tool.

not in my hobby budget. right now. but yes a hakko FR-301 can do the job quick.

[Cerebus]

So yeah, I had put it back the wrong way around... luckily it did not cause any damage and the scope has been just fine for 5 years now !

Yep, I know exactly what you are talking about, and I won't say how I know, multiple times........... 

Cerebus' rules for protecting Cerebus from Cerebus.

• Any board that Cerebus designs that Cerebus is likely to use powered from a bench power supply with flying leads are to have across all power lines reverse biased diodes that are rated in excess of the current any bench power supply that Cerebus is likely to use to supply them.
  
• If any two internal connectors on a board (or inside an enclosure) are identical they shall have keying to make them non-interchangeable. If this isn't possible wires shall be loomed such that it is not possible for Cerebus to put the wrong plug in the wrong socket without stripping the loom down.
  
• Boards shall have only one way that they fit into their intended enclosures and if it is physically possible to put them in the wrong way around then there shall be some feature (such as irregular mounting hole spacing) that makes it obvious that they are not meant to go that way around.
  

[Specmaster]

I think he needs a desoldering tool, using wick like that takes a long time, just a few seconds with a proper tool.

not in my hobby budget. right now. but yes a hakko FR-301 can do the job quick.

There are plenty of cheaper but equally good alternatives out there. I have a Duratool device, works really well.

[Martin Miranda]

I think he needs a desoldering tool, using wick like that takes a long time, just a few seconds with a proper tool.

not in my hobby budget. right now. but yes a hakko FR-301 can do the job quick.

There are plenty of cheaper but equally good alternatives out there. I have a Duratool device, works really well.

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

[Specmaster]

I think he needs a desoldering tool, using wick like that takes a long time, just a few seconds with a proper tool.

not in my hobby budget. right now. but yes a hakko FR-301 can do the job quick.

There are plenty of cheaper but equally good alternatives out there. I have a Duratool device, works really well.

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

Thats the one, a few of us on here have the same model, it is also sold under other brand names.

[Cerebus]

If life gives you lemons:



make marmalade!

SWMBO and I both went out independently the other day. While we were out we were both pleased with ourselves that we'd remembered we were out of lemons and picked some up en passant. We both got home to find that the other also had lemons. We like the unwaxed kind, which don't keep so well - certainly not well enough that a double batch will keep in good condition over the time it takes us to use them up. So, marmalade time! We still have some of the last batch of lemon marmalade I made so for variety I added some mandarins on the next shopping trip and we now have three jars full of "Lemming and Mandarin" and the overflow in a bowl that I'm ladling into croissants here. Yum!

[Neomys Sapiens]

So then it just me and my apprentice had to tackle the job over the next few months between us, and we uncovered many horrors along the way, lead cables, ...

Lead cables? Well I had never heard of that before. Can you describe these a little more if you remember? So heavy - how were they encased?

Here I found in an old building the worst wiring material that I've ever encountered. It consisted of twin wires isolated with paper, which might or might not have once been impregnated with something, in a thin lead- or tin-foil mantle. The conductors were made of a copper-iron alloy. That cables were brittle as hell and not easily recognized when covered with several layers of wall paint. The slightest bend - and you could take bets whether one or both wires and/or the mantle would snap. It might have been intended originally for use with a grounded mantle, but it was not done so in this installation.

Regarding cloth-covered wire, I was wondering what someone deemed so bad about it. But that was due to me thinking about a completely different material, i.e. Seidenlackdraht (oder -litze).
A solid or stranded conductor, sometimes isolated with a first layer of varnish (like magnet wire), then overspun with silk upon which another layer of varnish was applied was here a common wiring material for high-reliability, high-quality wiring of radios, instruments and control devices. I still have somewhere some differently coloured rolls which I did recover from a special use telephone switchboard. It came in many different colour combinations and is rather nice to work with. It fell out of use gradually when PTFE and other contemporary specialized wiring material was introduced.

[McBryce]

not a test equipment. but long days ahead of repairing this gear.

What's with the gloves? I could possibly understand it if he was repairing a device with lead-free solder, but this is old school stuff and gloves just make everything more difficult. Is he trying to express his inner "Louis Rossman"?

McBryce.

[Martin Miranda]

Is he trying to express his inner "Louis Rossman"?
McBryce.

  

[Specmaster]

not a test equipment. but long days ahead of repairing this gear.

What's with the gloves? I could possibly understand it if he was repairing a device with lead-free solder, but this is old school stuff and gloves just make everything more difficult. Is he trying to express his inner "Louis Rossman"?

McBryce.

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

[Neomys Sapiens]

We did already discuss the tektronix T202 (the Tek mutation of the dreaded 'Createk Signalcomputer'. Here one is for sale:
https://www.ebay.de/itm/334302262229
Here it can be seen how Tek was able to offer the silly thing as 'battery operated'. They used a separate battery module (the black box in the picture). This was connected to the power input DIN (diode) connector instead of the regular power supply. The clear plastic part is both a desk stand and a front protector, depending on which way it is snapped over two hexagonal extrusions on the side of the case. Any time you snap it on or release it you fear for it's survival. But having compared it again on this occasion - the Tek implementation is wayyy better than the original one, but still crappy when compared to a 222.

[Cerebus]

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

Ditto. But I'll add to that "yuck" factor or sticky factor. That is handling anything one would classify as "yucky" (like cleaning out the dustbin) or physically sticky. In the latter case doubly so if it's something like epoxy resin that won't just wash off with soap and water. If it's something that one can wash off quickly and conveniently I won't wear gloves. You cannot make marmalade without getting sticky mitts, repeatedly getting sticky mitts; I don't know how Paddington does it with all that fur. I lost count of how many times I rinsed my hands while making that marmalade.

Metaphorically I'm "a man who doesn't mind getting his hands dirty" but in fact I do hate getting my hands dirty. It's not the dirtiness per se that bothers me, but years of lab training and the like means that if my hands are dirty then I mentally flag them as contaminated and go around desperately avoiding touching other things, clothes, door handles, light switches until I've got them clean. This is how people with pukka OCD think, but unlike people with OCD I just need to wash my hands once and I'm a happy bunny again.

[Vince]

We did already discuss the tektronix T202 (the Tek mutation of the dreaded 'Createk Signalcomputer'. Here one is for sale:
https://www.ebay.de/itm/334302262229
Here it can be seen how Tek was able to offer the silly thing as 'battery operated'. They used a separate battery module (the black box in the picture). This was connected to the power input DIN (diode) connector instead of the regular power supply. The clear plastic part is both a desk stand and a front protector, depending on which way it is snapped over two hexagonal extrusions on the side of the case. Any time you snap it on or release it you fear for it's survival. But having compared it again on this occasion - the Tek implementation is wayyy better than the original one, but still crappy when compared to a 222.

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...

[Neomys Sapiens]

Holding the DMMcheck in my hands, I am even less enamored towards its case. ESPECIALLY with the LC option board fitted, it is going to be a PITA to access the battery. And I dislike to handle that board even in the basic version without necessity. As a first measure, I'll make the screws captive by means of small half moon clips, so that the stack will stay alignend and none of the distance rolls can escape. Also, when set down, it would rest on the screws, not the board.  But I would still prefer a direct access to the battery.

[Robert763]

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.