Test Equipment Anonymous (TEA) group therapy thread

[Specmaster]

Friend gave me 50 Euros, so minus the 14 Euros I spent for the new LED strips, that's 36 Euros gain. A miracle, it's zero usually.
He said he will try to extract a bit more from the owner and if successful, will pass it on to me.

So, I call it a good day today. TV is fixed, got some money for my work, and TV is out of my bench and living room, less clutter... I can see the floor tiles again now and can go to the loo at night without banging my legs on that TV. That's good.

EDIT : just got a call from my friend, he arrived at the owner's place. TV still works, it survived the transport. Talked a bit with the owner, he said he would give me 50 more Euros. So 100 Euros total, minus 14 Euros for the new strips, that's 86 Euros gain for one repair. A history first, almost worth the trouble...

Weren't they also the guys who gave you the notebook that helped you get your new job?

The friend that brought me this TV (which is owned by a colleague of his, which I don't know personally), yes is the same friend that lent me his old work laptop for the interview the other day. I gave it back to him after the interview, of course, it's his....

Any further news about the interview yet?

[bd139]

Quick sanity check. Just did a transformer impedance measurement. It's the tiny little transformer in the HP 427A. Doing a new power supply simulation for it...

So unloaded voltage = 47.4V AC
Loaded voltage = 43.2V AC with 2.35K load

2350 * ((47.4/43.2)-1) = 228 ohms

Smells high to me but might accurate. Is this a sensible figure?

[Vince]

Friend gave me 50 Euros, so minus the 14 Euros I spent for the new LED strips, that's 36 Euros gain. A miracle, it's zero usually.
He said he will try to extract a bit more from the owner and if successful, will pass it on to me.

So, I call it a good day today. TV is fixed, got some money for my work, and TV is out of my bench and living room, less clutter... I can see the floor tiles again now and can go to the loo at night without banging my legs on that TV. That's good.

EDIT : just got a call from my friend, he arrived at the owner's place. TV still works, it survived the transport. Talked a bit with the owner, he said he would give me 50 more Euros. So 100 Euros total, minus 14 Euros for the new strips, that's 86 Euros gain for one repair. A history first, almost worth the trouble...

Weren't they also the guys who gave you the notebook that helped you get your new job?

The friend that brought me this TV (which is owned by a colleague of his, which I don't know personally), yes is the same friend that lent me his old work laptop for the interview the other day. I gave it back to him after the interview, of course, it's his....

Any further news about the interview yet?

Nope, though I wasn't expecting any !  Since the HR boss contacted me last Wednesday to make me an offer, it was then him waiting for me to reply yes or no to his offer. Had one week to do so. Dead line this Wednesday then.  As "planned" I replied to him only today, because I didn't want to look desperate / begging by replying "yes" right there and now over the phone...

Got an immediate automated response " Sorry I am on hols 'til 22nd of August, please contact Mister X if in need ".

So I contacted Mister X instead. Quick reply, asked me to send him a few documents, the usual stuff to establish a contract. ID card, social security number, IBAN number, copy of the latest diploma, this and that... and that he needs it for Thursday no later, because not much time to process my case before I start in 2 weeks.

So I will do that...

He did ask for a "Work certificate " though, and I don't see what that is.... asked him what document he was talking about exactly,  but no reply as of now, 22H30... maybe tomorrow morning...

[Robert763]

Quick sanity check. Just did a transformer impedance measurement. It's the tiny little transformer in the HP 427A. Doing a new power supply simulation for it...

So unloaded voltage = 47.4V AC
Loaded voltage = 43.2V AC with 2.35K load

2350 * ((47.4/43.2)-1) = 228 ohms

Smells high to me but might accurate. Is this a sensible figure?

That is not just an impedance check, it's a regulation check. A lot of small power transformers have very poor regulation. Give it a bit of load, say 10k, and compare the voltage at that with the voltage with 10k & 2k35 in parallel.

[Neomys Sapiens]

The reason for skipping some letters/numbers is the low resolution silkscreen, which make an easy confusion: I-L-1, O-Q-0, G-C, U-V; not to mention how it look after some (mis)handling...
Here's an example:

Yes, but there seems to be no standard. Where JAMMA and EDAC states "G" is to be ommitted, your example includes "G". So my question was: How did HP handle that?

Tektronix used numbers on both sides of the card edge connectors and called the sides A and B.

This (attachment) is how I remembered it for the MILSPEC world even before looking: Large I,O,Q and small l and o are not to be used.
And yes, there are exceptions and deviations. I found about 5 in 10minutes. After 20 minutes I was convinced that the DLA and the technical branches of the uni(n)formed services are full of perverts.
 

Remark: the connection to my post about composite pinouts is pure coincidence.

[Cerebus]

Quick sanity check. Just did a transformer impedance measurement. It's the tiny little transformer in the HP 427A. Doing a new power supply simulation for it...

So unloaded voltage = 47.4V AC
Loaded voltage = 43.2V AC with 2.35K load

2350 * ((47.4/43.2)-1) = 228 ohms

Smells high to me but might accurate. Is this a sensible figure?

That's <10% regulation which sounds fine (quite good actually) for a ~1VA transformer. I'm making the assumption that your 2k35 is a realistic load for that.

[Zenith]

The model numbering is a bit confusing, the 5326A/B/C are 50MHz only, 5327A/B/C have the 550MHz prescaler added, B models have the DVM added, C models have time interval mode removed.
The early ones predate the 10544A oven, hence why the later ones, with exactly the same model number & letter have the redesigned motherboard.

There are three custom ICs for adding the 8th digit option, these are difficult to obtain NOS, they can be found from sellers that only flog the readout boards, but I don't like buying from these sellers knowing they probably destroyed working machines.

These are the two I own, the early 5326B below, crystal board is on the right, next to the side frame..

David

This is mine.


I think there's provision for an OCXO. There look to be solder points, but I imagine there should be a socket.

I had vague thoughts that the extra Nixie would just be a matter of finding the right Nixie and a 74141. No, three custom chips. I can't really see that happening without coming across a total wreck with the right parts. I wonder if it would be possible to make up a daughter board that would do it.

The fan looks a more approachable problem than I'd thought at first glance. There must be a modern fan that fits, or can be adapted, and has the right airflow and pressure. I'd be more tempted to use it if it didn't kick up that din.

[mnementh]

   

Printed successfully, but too fine detail; not enough mass in the "snap-together" bits. They just fall apart.

In the middle of a complete redesign. You can click on the link above and see current iterations. New version should print well at 0.20LH, tho.

mnem
"The role of failure in design."

   3D Model Web Viewer

Rev 11 printing. A wee bit more material now... 

mnem
          ...and there might have been a little scope creep; I should probably confer with my assistant, Mr Bluebottle fly...
*yawwnnnn*

[bd139]

Thanks to Cerebus and Robert for the transformer tips. Sussed it now.

Interestingly the HP 427A in DC and AC volts mode consumes a whopping 1mA of current at 24V which is quite frankly bugger all. At lowest ohms range it consumes only 13mA. Very efficient design.

I did some experimental simulations based on the transformer regulation and impedance to work out what regulator would be suitable to replace the original NiCd battery and it looks like a simple LM317 will do the job. I spent some time optimising the design for lowest power dissipation and reasonable drop out safety and have a final design I will build. Unfortunately attempts to design shunt regulators which could be dropped in instead of the battery were unsuccessful. They had too much ripple. The meter's internal supply has poor PSRR as it's designed to work of low impedance sources like batteries. The only remaining option is to modify it to contain a linear regulator.

I'm going to do a completely overkill job of this of course. Watch this space 

[duckduck]

My offer to show how I re-capped an hp 5248L PSU back in August 2020 has generated an interest and a request for pictures on how I did it. So I pulled out the counter this morning and took some new pictures. The capacitors that were replaced are C4, C6, C7, C8, C9, and C10.
<SNIP>

Thank you, med. Very nice.

Here's another way to mount the new caps in a 5245L using adapter PCBs. Shahriar only mentions that "[the old capacitors] are very hard to take out without destroying them".

[mnementh]

mnem

[med6753]

My offer to show how I re-capped an hp 5248L PSU back in August 2020 has generated an interest and a request for pictures on how I did it. So I pulled out the counter this morning and took some new pictures. The capacitors that were replaced are C4, C6, C7, C8, C9, and C10.
<SNIP>

Thank you, med. Very nice.

Here's another way to mount the new caps in a 5245L using adapter PCBs. Shahriar only mentions that "[the old capacitors] are very hard to take out without destroying them".

He also doesn't show how he secures his adapters to the chassis.  The original outer rings that the old capacitors were mounted to appear to still be riveted to the chassis. So what's holding his adapters in place?

Granted, the result is much neater but my method is much less invasive. 

[cyclin_al]

Look at the chemicals used in Teflon manufacturing next, it's "PCB oil" (not circuit board related) all over again - just harder to replace this time 
Then look at the Arsenic dust canada has in underground mines on a biiig lake shore. Then look at uranium manufacturing residue and let's not get started on spent fuel reprocessing Only upside is, we'll make the place inhabitable for humans looong before it's inhabitable for "nature".

Yes, we have a lot to deal with to make things inhabitable.

Part of it is the learning curve, we (humankind in general) need to be better at doing our homework.  Teflon is just a subset of the chloro- flouro-carbon problem.  No one bothered to really understand those chemicals, or maybe covered up the downsides?  They were certainly marketed as miracle products.  Nasty stuff.  Small steps are being taken.  Flourinated ski waxes were banned for world cup and Olympic races, and throughout europe at the beginning of 2022.  As most production of ski waxes is in Europe, that stops the new production.  That is a tiny token step in the right direction.  That still leaves a lot of skiing where those nasty things are still being used.  Yep, those waxes are still in use in Canada, except at my local club; that was a painful transition.

The teflon on cookware is still a much bigger use.  SWMBO still abuses it since those are actually serious warnings on the cookware.  Food or water keeps the cookware temperature below the temperature that the teflon vapourizes.  Nothing in the cookware on the stove quickly leads to vapourized teflon.  Why bother manufacturing the stuff if everyone is going to turn it into vapour anyways? 

You must be thinking of the Asbestos (not arsenic) mine in Canada.  Mining stopped in 2011.  That does no good, as the stuff that is already mined is still being exported and put into various products. 

Do we even know how nasty lithium mining is?

I learned something, and am not impressed. 

We each have to add one to our lists; it turns out there are both Arsenic dust and Asbestos dust problems that need remediation.

[BU508A]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

[med6753]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

All I can say is "WOW".  And I noticed that it seems all his TE is nearly new rather than vintage. Just the opposite of my stuff. Must have cost him a fortune.  And it appears he puts Carlson to shame. 

Don't know where he is located but yes, most residences here have basements or living space below grade. Therefore it is extremely important there's good drainage and sealed foundation to prevent water intrusion. It is rare to have a residence built solely at grade. In the southern states it is just the opposite. Basements or living space below grade is rare.

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   
 

[Cubdriver]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

All I can say is "WOW".  And I noticed that it seems all his TE is nearly new rather than vintage. Just the opposite of my stuff. Must have cost him a fortune.  And it appears he puts Carlson to shame. 

Don't know where he is located but yes, most residences here have basements or living space below grade. Therefore it is extremely important there's good drainage and sealed foundation to prevent water intrusion. It is rare to have a residence built solely at grade. In the southern states it is just the opposite. Basements or living space below grade is rare.

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   

I think Shahriar is up in Canuckistan, so I figure he likely has a basement.  Being born and raised here in the northeastern US where basements are the norm, the idea of not having one seems foreign to me.

-Pat

[Specmaster]

This is a video that Saskia will love I'm sure 

[BU508A]

I think Shahriar is up in Canuckistan, so I figure he likely has a basement.  Being born and raised here in the northeastern US where basements are the norm, the idea of not having one seems foreign to me.

-Pat

Nope. Murray Hill, NJ, USA

[bd139]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

All I can say is "WOW".  And I noticed that it seems all his TE is nearly new rather than vintage. Just the opposite of my stuff. Must have cost him a fortune.  And it appears he puts Carlson to shame. 

Don't know where he is located but yes, most residences here have basements or living space below grade. Therefore it is extremely important there's good drainage and sealed foundation to prevent water intrusion. It is rare to have a residence built solely at grade. In the southern states it is just the opposite. Basements or living space below grade is rare.

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   
 

He does a lot of "danger money" repairs. You know where the vendor has quoted a whole new unit for the repair and the client doesn't want to pay that much but will go half way. That requires expensive kit and he probably charges out decent amounts of money for the privilege.

[med6753]

I think Shahriar is up in Canuckistan, so I figure he likely has a basement.  Being born and raised here in the northeastern US where basements are the norm, the idea of not having one seems foreign to me.

-Pat

Nope. Murray Hill, NJ, USA

Give or take about 100 miles from me and just west of Newark, NJ.

[tautech]

I think Shahriar is up in Canuckistan, so I figure he likely has a basement.  Being born and raised here in the northeastern US where basements are the norm, the idea of not having one seems foreign to me.

-Pat

Shahriar works for Bell Labs, New Jersey so probably don't live far from there.
Yep if you watch Dave's vid for a few minutes more Shahriar says he's setup in most of his basement, a lab of 1000+ft².
It's the same lab as we see all his TSP vids shot in but we don't generally get any sort of tour like he was rubbing Daves nose in ! 

Edit to add, if you've got it flaunt it !

[med6753]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

All I can say is "WOW".  And I noticed that it seems all his TE is nearly new rather than vintage. Just the opposite of my stuff. Must have cost him a fortune.  And it appears he puts Carlson to shame. 

Don't know where he is located but yes, most residences here have basements or living space below grade. Therefore it is extremely important there's good drainage and sealed foundation to prevent water intrusion. It is rare to have a residence built solely at grade. In the southern states it is just the opposite. Basements or living space below grade is rare.

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   
 

He does a lot of "danger money" repairs. You know where the vendor has quoted a whole new unit for the repair and the client doesn't want to pay that much but will go half way. That requires expensive kit and he probably charges out decent amounts of money for the privilege.

Yes, he has done repairs for the Ebay seller Alltest Instruments. Those are the guys that pack stuff that will survive a nuclear blast. 

[Cerebus]

A quick glance into Shahriar's lab:

https://youtu.be/s2KkgI-kyK0?t=308

 

All I can say is "WOW".  And I noticed that it seems all his TE is nearly new rather than vintage. Just the opposite of my stuff. Must have cost him a fortune.  And it appears he puts Carlson to shame. 

Don't know where he is located but yes, most residences here have basements or living space below grade. Therefore it is extremely important there's good drainage and sealed foundation to prevent water intrusion. It is rare to have a residence built solely at grade. In the southern states it is just the opposite. Basements or living space below grade is rare.

This house was built in the 1850's and has a basement, with a dirt floor. There's even a small spring in one corner that comes to the surface and drains out through the foundation. But it does not smell musty or mildewed because there is good airflow.   

I think Shahriar is up in Canuckistan, so I figure he likely has a basement.  Being born and raised here in the northeastern US where basements are the norm, the idea of not having one seems foreign to me.

-Pat

Where I grew up on the south coast almost all the older houses had basements (say pre-WWII), often with a street level hatch to deliver coal through. None of the houses I've lived in in London have had basements. Never really thought about the discrepancy until now and I can't offhand see geography being the motivating factor - Brighton is on, very wet, chalk and London is on a similarly wet [clay] river basin so they are both rather damp places for basements.

[mansaxel]

Where I grew up on the south coast almost all the older houses had basements (say pre-WWII), often with a street level hatch to deliver coal through. None of the houses I've lived in in London have had basements. Never really thought about the discrepancy until now and I can't offhand see geography being the motivating factor - Brighton is on, very wet, chalk and London is on a similarly wet [clay] river basin so they are both rather damp places for basements.

Colin Furze does offer some insights in building things underground in what I naîvely assume is somewhere in greater London area. His house didn't have a basement either..

https://youtu.be/A_ESR5zoGYQ

[bd139]

He's out in Lincolnshire.

https://find-and-update.company-information.service.gov.uk/officers/FvDQykChz0ahbK_Gy8_3dO-oR98/appointments

Makes a fair bit of cash. Check his company accounts filings