Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

No no no, to clean those transistors you don't need teeth or toothbrushes, what you need are wire brushes to remove the rust flakes.

[Robert763]

Added a charge line to my pulser. Next step is working on better shaping of the pulse top....but that's another day's problem. 

Also got a wild pic while experimenting with a long exposure app on my phone. I think the lighting confused it.

Ooooh.... artsy.

"Electric Fuzz" would be a good title.

mnem
or maybe "Bad Hair Day"...

Sell it as a NFA 

[Robert763]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

[Robert763]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

[tggzzz]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

Eeek!

The nearest I got to that was when testing my sound-to-light box. I touched the SCR's live case with one hand and a neutral track with the other. Fortunately it was only a light touch, my biceps uncontrollable contracted, and I dropped the board. Shocking in two ways!

[tautech]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

Which Tek ? 
The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

[beanflying]

There was a vintage slightly crusty HP current probe available on evilbay in Oz  eBay auction: #165025864057

Here's another one -- not as cheap but still interesting. NAWTS, of course.

There is a big difference between the HP and the Tek (apart from obvious colour and age). The HP is AC only, the Tek is AC and DC.

Which Tek ? 
The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

Apart from not seeing the point of displaying a straight line on a scope I have a pair of nice 6 1/2 digit meters with logging capabilities and a set of really accurate shunts I can probe if needed for DC or near DC that I could easily look at on a scope channel if required.

So call me curious and it has been a while since I added to the TEA toys so I thought I should

[Specmaster]

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Same people that use their teeth to strip wire insulation.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

And your still here to tell the tale, were you standing on a nice thick rubber mat by any chance at the time? 

[BU508A]

Anybody here in Germany interested in a Keysight 34138A test lead set? (NAWTS)

https://www.ebay-kleinanzeigen.de/s-anzeige/keysight-34138a-test-lead-set/1850482996-168-16385

[AVGresponding]

Ok, I fixed the broken TO-5 tranny leg. In case you haven't figured it out yet, I am a master of ghetto fab...

The two dead digits are confirmed deader than dead things, I'll buzz the trannys out but I suspect a case of terminal inside-the-potted-box-itis, which is to say the interface between the drivers and the nixies is that weird lamp box that has to do with the
Well this is strange, one of them is trying to light now... time to start buzzing out trannys and especially those carbon craposition resistors. Also "thou shalt check voltages"... hmmm...

My guess is you soldered a bit of capacitor leg to the case of the transistor...?

mnem

Nope, I soldered the two parts of the transistor leg back together, in circuit. I didn't even check if it was the collector tbh.

I need to check the OP to be sure, but I don't think we've had "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than your teeth".

Tesco website is a bit fooked atm, DDOS? Needed more toothbrushes...   

Had all the topside boards out of the 5245L, gently cleaned (not gently enough, a rusty transistor leg broke, plugging the Metcal in right now), adjusted some clearances (some of those TO-5 case were, shall we say, inadvertently thermally coupled?).
Swapped some display boards around, and as soon as I've fixed that tranny leg on the A18 display board I'll give it a burl.

Who uses their teeth to clean transistors?

Pardon me for using the idiom instead of re-establishing context. "you know you're a TE addict when you use a new toothbrush to clean rusty transistors rather than to clean your teeth".

No no no, to clean those transistors you don't need teeth or toothbrushes, what you need are wire brushes to remove the rust flakes.

That would have resulted in instant destruction, even with my Dremel-style soft brass or fibre brushes. These are TO-5 transistors with 0.6mm diameter legs before they got corroded.

I got cured of that habit as a teenager when I used my teeth to strip a bit of zip cord. Only to find my brother had plugged the other end in to a 240V outlet with out me noticing. 
That hurt 

And your still here to tell the tale, were you standing on a nice thick rubber mat by any chance at the time? 

Since he was sucking on both line and neutral simultaneously, the earthing arrangement is largely irrelevant.

Anybody here in Germany interested in a Keysight 34138A test lead set? (NAWTS)

https://www.ebay-kleinanzeigen.de/s-anzeige/keysight-34138a-test-lead-set/1850482996-168-16385

@Saskia, after you!   

[dl6lr]

Anybody here in Germany interested in a Keysight 34138A test lead set? (NAWTS)

https://www.ebay-kleinanzeigen.de/s-anzeige/keysight-34138a-test-lead-set/1850482996-168-16385

I ordered two sets in 2020 from an ebay seller levin97 for €10,- per set.

[BU508A]

Anybody here in Germany interested in a Keysight 34138A test lead set? (NAWTS)

https://www.ebay-kleinanzeigen.de/s-anzeige/keysight-34138a-test-lead-set/1850482996-168-16385

I ordered two sets in 2020 from an ebay seller levin97 for €10,- per set.

Yes, I did that, too.
But looking at the current results makes this offer of 25 EUR somewhat attractive.

https://www.ebay.de/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=34138A&_sacat=0

[srb1954]

I do not know what is worst: RIFA or Win11.
I think the disappointment to the users will be comparable.

RIFAs contaminate the whole room (or more), not just the laptop.

Yes, but the stench from a RIFA explosion dissipates in a couple of weeks. I suspect we will be afflicted with Win11 for much longer than that.

[med6753]

Tucked away in the TEA closet but readily accessible. Total cost of materials, excluding stain and poly which I had on hand, was approx $130 USD.

[srb1954]

Ok, I fixed the broken TO-5 tranny leg. In case you haven't figured it out yet, I am a master of ghetto fab...

The two dead digits are confirmed deader than dead things, I'll buzz the trannys out but I suspect a case of terminal inside-the-potted-box-itis, which is to say the interface between the drivers and the number readout bulb is that weird lamp box that has to do with the
Well this is strange, one of them is trying to light now... time to start buzzing out trannys and especially those carbon craposition resistors. Also "thou shalt check voltages"... hmmm...

The carbon resistors weren't that bad, I had to strip some of them from a later board (from Sphere) & repopulate it with salvaged parts (some slighty out of tolerance), to match the earlier parts list from the 20MHz 5243L, it worked fine after that. 
It got posted here some time ago, the traces on the photo-resistor plate had been eaten by corrosion too.
The transistors got downgraded from Silicon to Germanium as well, as per the original damaged board.
https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg3453170/#msg3453170

Re: the number readout bulbs, two in my 5248M were completely dead, due to the glass being cracked from pin corrosion (BD, the previous owner did what you said, cleaned it & dumped it back on ePay for me to buy) and the 5243L had one bulb that was missing a number 6, it was found to be no longer connected inside the bulb.

David

I had the same problem with my 5245Ls with erratic performance of some of the Nixies. Corrosion on the Nixie pins caused micro cracking to the seals letting some of the neon out or letting air in.

If you have good brightness on the Nixies but some numbers don't display or it flickers between numbers check the operation of the neons in the decoder/latch module. I found considerable variation in the firing voltages of these neons making the latch function and decoding erratic.

However, I can't really complain about these faults though as I only paid $25 for a pair of 5245Ls together with some extra plug-ins.

[Vince]

Added a charge line to my pulser. Next step is working on better shaping of the pulse top....but that's another day's problem. 

Also got a wild pic while experimenting with a long exposure app on my phone. I think the lighting confused it.

Funky !

Can we have a pic with a clean pulse and time base setting so we can measure the rise time ? 

And forgive the stupid newbie question but what is a "charge line" ,  not much info online to my dismay. Found " charging line " or "line charging", often not even pertaining to electronics...

What does it consist of, its role and how why did you expect it might modify the rise time (in your last post you said rise time without charge line was irrelevant ) ?  I mean I can see it lengthens the pulse of course, but what's the impact on rise time ?

Thanks ! 

[Vince]

Question, for those of you who have the 575. I just saw this pop up on Ebay:
https://www.ebay.com/itm/284416799976

At $520 for BIN, or even $400 for bidding sounds pricey to me, but I'm not at all familiar with it's historical selling prices. What do you think is a good going price for a 575 in unknown condition?

Don't know squat about the US market, but in Frog land it would already be sold...

Price is typical and given it looks brand new cosmetically, it would sold at that price within 5 minutes, even if we don't even know if it powers up (main transformer or CRT might be damaged, show stopper), just because they are so rare.

Seems to me the people here/frog land who are looking for old Tek stuff are the older guys retired with lots of cash and time to search ads. They always arrive first and buy pretty much regardless of price or condition, because the 575 is just too rare and in high demand. So basically anything that comes up is immediately sold. You buy first, and sort the details afterwards.... basically like what I am doing with mine right now...

[AVGresponding]

Oh, I "accidentally" acquired a lot of 18 outside micrometers on ebay...

https://www.ebay.co.uk/itm/JOBLOT-18x-MITUTOYO-STARRETT-MOORE-WRIGHT-OUTSIDE-MICROMETERS-TOOLS-/265270785540

[BU508A]

Added a charge line to my pulser. Next step is working on better shaping of the pulse top....but that's another day's problem. 

Also got a wild pic while experimenting with a long exposure app on my phone. I think the lighting confused it.

Funky !

Can we have a pic with a clean pulse and time base setting so we can measure the rise time ? 

And forgive the stupid newbie question but is a "charge line" ,  not much info online to my dismay. Found " charging line " or "line charging", often not even pertaining to electronics...

What does it consist of, its role and how why did you expect it might modify the rise time (in your last post you said rise time without charge line was irrelevant ) ?  I mean I can see it lengthens the pulse of course, but what's the impact on rise time ?

Thanks ! 

The charge line is simply a coaxial cable where it's capacitance has been used.

Here is my charge line:


This is the schematic of the Jim-Williams fast pulse generator:


C₁ is essentially the capacitance of the coax cable.

HTH

Edit:

Here has somebody made a charge line on the PCB:


Source:
http://www.siliconvalleygarage.com/projects/picosecond-pulser.html

[Zucca]

Question for RPN hp calculators lovers.

I set mode ENG with 3 decimal digit.
I recall pi and I get

Code: [Select]

3.142E0fine with me!

Then I multiply by 100 and I get

Code: [Select]

314.2E0what? 
Expected:

Code: [Select]

314.159E0
I know internally is all good (by pressing "SHOW" you get the full number) but my understanding of mode ENG 3 is:

Code: [Select]

XXX.YYYENwhere the XXX digits are optional and the three YYY must be shown since I selected 3. Of course N is a multiple of 3.

It looks like it shows what make sense to the math considering the starting number NOT what it the closest number to the current internal one.

My TI-68 was not like that....

PS: I compromise now by selecting ENG 4 as mode.

[mansaxel]

The infamous P6021 and P6022 current probes are AC only probes also and both can be paired with the Type 134 current probe amp for 50 ohm output.

Apart from not seeing the point of displaying a straight line on a scope I have a pair of nice 6 1/2 digit meters with logging capabilities and a set of really accurate shunts I can probe if needed for DC or near DC that I could easily look at on a scope channel if required.

So call me curious and it has been a while since I added to the TEA toys so I thought I should

The -hp- one is AC-only, because they already offered the 428b which is the original DC clamp. It too has a scope compatible output. I actually haven't looked at it in a scope. Maybe I should, it's rated to 400Hz.

[Vince]

The charge line is simply a coaxial cable where it's capacitance has been used.

Here is my charge line:


This is the schematic of the Jim-Williams fast pulse generator:


C₁ is essentially the capacitance of the coax cable.

HTH

Thanks, clear and concise, you should teach ! 

[xrunner]

Question for RPN hp calculators lovers.

I just wrote this up before you posted ...

So last night when the forum was down I was on Discord and Zucca was wondering why his hp 42S was displaying what seemed to him to be a wrong number of digits after the radix. I have the original manual but it doesn't really explain this very well.

For example, he set the display to ENG 03. He then recalled pi and was presented with

3.124E0

I believe he then multiplied by 10 and viewed this

31.42E0

He was not sure why it didn't display three decimal places like this

31.416E0

^^^ that is what it displays when I set it to ENG 04 (it rounds the last digit up from 5 to 6).

Well, it is operating exactly as it should. I also have a newer hp 35s which operates exactly the same way.

If you set the display to FIX 03, it will FIX the decimal places to always show 3. But that isn't how ENG and SCI mode works. What does this mean then: ENG 03? It means it will display 3 digits after the first digit. It does not mean three decimal places.

You can read the manual for the excellent Free42 PC application which works just like the real calculator (one of which I own) -

2.6.4 The ENG function 
The ENG function puts the calculator in engineering notation. It looks like scientific notation but now
the first number does not need to be between 0 and 1 but can be between 0 and 1000 and the power
will be always 3 manifold (corresponding to the magnitude prefixes such as milli-, micro-, kilo-,
mega-, etc. used in engineering units).  For example: 100 will be represented by 100.E0 in ENG 2
mode while 1000 will be 1.00E3 in the same mode. Why do we get 100.E0 for 100 instead of
100.00E2 in ENG 2 mode? Because the calculator shows in engineering mode the same number of
digits it shows in scientific mode.

https://thomasokken.com/free42/doc/42s.pdf

Corrected: The question was from Zucca Not Neomys Sapiens

[Zucca]

It's my first Agilent.

Nice horse! Agilent PSU are they only one I would buy if I had not sold my soul to TTi!

[Zucca]

Because the calculator shows in engineering mode the same number of
digits it shows in scientific mode.

Retarded design choice for me.