Test Equipment Anonymous (TEA) group therapy thread

[mansaxel]

A bit more detail on the CMS33 repair.

I am full in Nerd-Envy^(tm) mode.  Really need to up the RF part of the lab. Also really need to get priorities right; car, spring and summer vacations.

[Saskia]

ender has found a buyer.

lying flat due to allergic fever ...

[Neomys Sapiens]

Well, my finger hit the buy button before I even could think what was happening... Roughly US$150 all up..

I see TM500, I buy TM500......... 

And it's a late one....nice!

[Neomys Sapiens]

Sooo...closing a deal for a Fluke 115, as it is the perfectly fitting solution for the mentioned toolcase.

Asking again: anyone interested in a 79-III? With manual and standard leads, foil still on display, some chafing traces, otherwise clean. Usage in the lower single digit hours.

[Saskia]

potential interest in the 79

[tautech]

ender has found a buyer.

lying flat due to allergic fever ...

GWS girl or we'll start polishing the bullet ! 

[Peter_O]

Inspired by Dave's HP6643A video


I catched an 66xx from the boat anchor class.

It's a Agilent 6653A, delivering 35V 15A max.
Net weight 25kg.

Did a quick test with my 8A analogue load 


The accuracy of the current limit is not that bad.
S/N sticker says its from year 2000, looking inside I'm not totally conviced, it might be older in parts.

Trafo and cooling block are quite some armatures.
Defintely this guy is one to stack at the bottom.




There has been some repair or exchange of pcbs, as some cables carry handwriting. And there is a funny sticker on top of one of the caps:


Now I have to fetch a connector for the remote sensing etc.

Following this post a lot of you gave valuable hints towards Phoenix 5.0 or 5.08mm connectors, thx again to all of you.
Some might have been betting on my getting the measurement right.   

Here's the resolution: 5.08mm it is.

Finally I did not pay some 7 Euro for one connector but decided to get this box of 2,3, and 4 pin connectors: "beihuazi® PCB Screw Terminals 5.08 mm Straight Screw Terminal Block Plug-In Connection Blocks for PCB PCB Circuit Board Terminal Block 2EDG Socket?2 Pin 10 Pairs, 3 Pin 10 Pairs, 4 Pin 5 Pairs" for 11 Euros only.


They do fit perfectly fine and have a strong hold.

Don't want to drill holes in the front at the moment.
So I did a makeshift printed box with output and sense connectors and a sense switch.



It's connected with 4mm² wires to the back, which should be not that bad for currents of 15A max.


On the backside a little mounting thingy helps



A quick test with 25V and about 5A into a resistor shows, that even with 4mm² to the front box and 2.5mm² to the resistor and a moderate current of 5A sense wires do make sense.

It's
24.994V on the PSU display, sensing at the resistor
24.999V on the HP3355A, sensing at the resistor
25.088V on the HP3457, sensing at the front box
25.222V on the Sig3055, sensing on the backside connectors

[Vince]

CRT saga update


Thanks everyone for your help and comments.

1) HV too high. Yes did cross my mind last night, thinking yeah maybe the electrodes in the CRT are fine it's just the HV too high causing the arcing.

2) Plastic base in bits : it's not hopeless ! It's only in 4 big chunks easily put back together, see below. I could superglue them back. As for the two hacksaw slits I made, 180° apart, I could reconstitute those as well : I kept the plastic saw dust in a little ziplock bag. I could mix it with glue to reconstitute / refill the slits. Common technique in wood working for small repairs.

3) Hollow pins : ah ! so that's how they do it !!!  I could not get how they could manage to crimp these pins with the plastic base in place ! 
So the wire sticks out of the pin, they cut it flush and solder the end.... yes looking closely at those pins, I could see some have their ends still hollow !
Boy I learned something, one less mystery in the universe !   OK, so I touched up all 14 pin ends.


Then I plugged the CRT temporarily as Dragon suggested.

Result ?  Well for one there was no sparking in between the pins at base of the neck, so that means even without the base in place, it doesn't spark.. so the base is not vital. I am sure it's better with it, but not vital.

The CRT still does exactly the same shit as before ! no more no less.
Also, if I tap gently here and there on the neck (GENTLY I said, not with a sledge hammer !  ), I notice that... I don't notice anything !  It does not appear to affect the behavior of the CRT in any way shape or form. I find that a bit strange... if the problem was internal damage, a bent electrode in there, or a broken or intermittent weld.. you would thing that taping would have SOME effect... but no.

ALSO, of great importance  : I played with the CRT for like I don't know, 20 minutes, and it does NOT make any sound any more, nothing ! Yet the CRT still does the exact same shit on the screen !
And I can't see any arcing inside the neck, nothing.

So... I am now at the point where I think maybe all that crazy shit on the scree, really crazy shit, might not be created by the CRT... just a tiny hope.

So I am now thinking, if just as a sanity check, that it's worth spending a little time probing the scope to see what signals are sent to the CRT. H and V deflection, Cathode voltage, brightness etc.... everything.


I am not used to HP scopes and the CRT is not as easy to probe as a Tek, so it will take me some time to get around that scope that's new to me....


Stay tuned 

[Cerebus]

... but then I decided that the foam gasket would not be able to provide a proper seal between the door skin and the speaker frame because the speaker is 2nd hand and the gasket has already had many years of compression applied to it.

A useful thing I keep a sheet or two on hand of is EVA foam, often sold in funky colours as craft supplies.

e.g. https://www.ebay.co.uk/itm/282978430287


Just the thing for cutting that kind of gasket out of. I've used it before to replace the gasket around a tail light when the original got less than watertight, it's still doing a good job years later.

[Cubdriver]

CRT saga update


Thanks everyone for your help and comments.

1) HV too high. Yes did cross my mind last night, thinking yeah maybe the electrodes in the CRT are fine it's just the HV too high causing the arcing.

2) Plastic base in bits : it's not hopeless ! It's only in 4 big chunks easily put back together, see below. I could superglue them back. As for the two hacksaw slits I made, 180° apart, I could reconstitute those as well : I kept the plastic saw dust in a little ziplock bag. I could mix it with glue to reconstitute / refill the slits. Common technique in wood working for small repairs.

3) Hollow pins : ah ! so that's how they do it !!!  I could not get how they could manage to crimp these pins with the plastic base in place ! 
So the wire sticks out of the pin, they cut it flush and solder the end.... yes looking closely at those pins, I could see some have their ends still hollow !
Boy I learned something, one less mystery in the universe !   OK, so I touched up all 14 pin ends.


Then I plugged the CRT temporarily as Dragon suggested.

Result ?  Well for one there was no sparking in between the pins at base of the neck, so that means even without the base in place, it doesn't spark.. so the base is not vital. I am sure it's better with it, but not vital.

The CRT still does exactly the same shit as before ! no more no less.
Also, if I tap gently here and there on the neck (GENTLY I said, not with a sledge hammer !  ), I notice that... I don't notice anything !  It does not appear to affect the behavior of the CRT in any way shape or form. I find that a bit strange... if the problem was internal damage, a bent electrode in there, or a broken or intermittent weld.. you would thing that taping would have SOME effect... but no.

ALSO, of great importance  : I played with the CRT for like I don't know, 20 minutes, and it does NOT make any sound any more, nothing ! Yet the CRT still does the exact same shit on the screen !
And I can't see any arcing inside the neck, nothing.

So... I am now at the point where I think maybe all that crazy shit on the scree, really crazy shit, might not be created by the CRT... just a tiny hope.

So I am now thinking, if just as a sanity check, that it's worth spending a little time probing the scope to see what signals are sent to the CRT. H and V deflection, Cathode voltage, brightness etc.... everything.


I am not used to HP scopes and the CRT is not as easy to probe as a Tek, so it will take me some time to get around that scope that's new to me....


Stay tuned 

Vince, I'd say that it's definitely worth further troubleshooting of the scope chassis.  As I mentioned yesterday, I think that if something were amiss in the e-gun assembly that you wouldn't be getting that nice sharp beam.  Perhaps your arcing noise was a bad connection at the base of the tube.

The rods holding the gun parts are likely glass.  You've probably seen this already given your interest ion old Tek iron, but on the off chance that you have not:


Fascinating to see how they were made back in the day.  Lots of precision hand assembly work!

-Pat

[AVGresponding]

just wondering, would it be possible to laser weld some broken stuff inside a CRT ?

Not in my case: the gap was too wide and they weren't in contact anymore.

It's an interesting idea, and I wouldn't rule it out, even in your case tggzzz. As the metal starts to melt, it'll blob, and that might be enough to re-establish contact.

Some difficulties that are easy to forsee are the potential for the glass to disrupt the beam, and to be melted by the beam if it's the wrong frequency. It might be possible to use the same trick as with ultrasound; focus two/more beams of lesser strength into one area to have the necessary power.


EDIT: Though I expect the difficulty and expense of the equipment would not be worthwhile in most cases...

[mnementh]

   And sorry; I take for granted that anybody can lay hands on these, as they're a standard hardware store item over here from the Hillman drawers in a variety of sizes and depths. Also SOP for car audio installers; certain kits of speakers even come with them standard. 

As a matter of fact, those abominations apparently  are so common in the US that you lot feel a need to replace something nice:

...with them. "ACK! THPPTT!" as Bill the Cat would say.

A caged nut, while a million times better, isn't really a particularly satisfactory solution either, too loose, rattley, needs a punched square hole and so on. There is, of course, a device designed to take a proper machine screw rather than some unter-fastener like a self tapping screw and it's called a rivnut:



I really can't understand why someone sane would eschew one of those for one of these POSes with all the sharp edges, corrosion traps etc.:

Fully aware. I've been using NutSerts where applicable since I was 12; grand-dad was a master machinist and did try to teach me a few things before he passed on.

Short version: They simply aren't the right part for this job.

1) They cost too much for this application. Not only are NutSerts a pretty expensive fastener, but there's time to install them. And then you also have to buy the correct screws. No way in hell you're going to get the average car stereo customer to pay for the extra parts and time to install 8 or 16 of these, and damn sure the shop owner isn't going to pay for it on a free stereo install. Especially when most of the name brand speakers they're selling come with the sheet-metal screws and clipnuts as part of the kit.

2) Machine screws are not the ideal fastener for this application, particularly if the speaker has a plastic frame. They are easy to overtighten and deform or crack the frame of the speaker, and they're a lot likelier to shake loose. Clipnuts by their nature are very resistant to this; they keep the thread under constant spring tension just like a locknut. Using sheet-metal screws makes it much less likely they'll be over-tightened as well.

3) Depending on the maker, NutSerts are often too thick once installed. Some are as much as 1-1.5mm thick once swaged in place. This will result in holding the speaker up off the panel, and make whistling/buzzing noise because the speaker doesn't seal properly.

   If machine screws were actually better in this application, we'd probably use U-nuts anyways cuz quicker. But they tend to be too thick, and still the same problems with screws rattling loose. The clipnuts usually used for car stereo installs are typically 0.3-0.5mm thick.

Cheers!

mnem
 

[Specmaster]

That's the conclusion I came to and went with pop rivets, very quick to install, used the old seal perfectly OK and working great. I can thoroughly recommend grabbing one of those drill adaptors for riveting, there is another one on Amazon that is considerably cheaper, made with a plastic case but judging from videos on YT, is more than capable for the job https://www.amazon.co.uk/Greatangle-Electric-Riveting-2-4mm-4-8mm-Cordless/dp/B08NC531YN/ref=sr_1_3?crid=LNFA14L4I9F5&keywords=rivet+gun+adapter&qid=1651186016&sprefix=rivet+gun+adaptors%2Caps%2C75&sr=8-3

I went with a metal version so it is more durable, around 3 times the price, but I'm sure the cheaper one is prefect for the job, but I needed one that was on prime for next day delivery and the metal just looked like it would be able to get into more confined locations. It whizzed through the 6 rivets (4.8 x 12 mm) on the speaker in considerable less time than it took doing a 4.8 x 5 mm rivet with a manual gun. Those rivets are very hard to do by hand, at least for me, I'm not as strong as I was when I was on the tools all the time.

[mnementh]

CRT saga update


Thanks everyone for your help and comments.

1) HV too high. Yes did cross my mind last night, thinking yeah maybe the electrodes in the CRT are fine it's just the HV too high causing the arcing.

2) Plastic base in bits : it's not hopeless ! It's only in 4 big chunks easily put back together, see below. I could superglue them back. As for the two hacksaw slits I made, 180° apart, I could reconstitute those as well : I kept the plastic saw dust in a little ziplock bag. I could mix it with glue to reconstitute / refill the slits. Common technique in wood working for small repairs.

3) Hollow pins : ah ! so that's how they do it !!!  I could not get how they could manage to crimp these pins with the plastic base in place ! 
So the wire sticks out of the pin, they cut it flush and solder the end.... yes looking closely at those pins, I could see some have their ends still hollow !
Boy I learned something, one less mystery in the universe !   OK, so I touched up all 14 pin ends.


Then I plugged the CRT temporarily as Dragon suggested.

Result ?  Well for one there was no sparking in between the pins at base of the neck, so that means even without the base in place, it doesn't spark.. so the base is not vital. I am sure it's better with it, but not vital.

The CRT still does exactly the same shit as before ! no more no less.
Also, if I tap gently here and there on the neck (GENTLY I said, not with a sledge hammer !  ), I notice that... I don't notice anything !  It does not appear to affect the behavior of the CRT in any way shape or form. I find that a bit strange... if the problem was internal damage, a bent electrode in there, or a broken or intermittent weld.. you would thing that taping would have SOME effect... but no.

ALSO, of great importance  : I played with the CRT for like I don't know, 20 minutes, and it does NOT make any sound any more, nothing ! Yet the CRT still does the exact same shit on the screen !
And I can't see any arcing inside the neck, nothing.

So... I am now at the point where I think maybe all that crazy shit on the scree, really crazy shit, might not be created by the CRT... just a tiny hope.

So I am now thinking, if just as a sanity check, that it's worth spending a little time probing the scope to see what signals are sent to the CRT. H and V deflection, Cathode voltage, brightness etc.... everything.


I am not used to HP scopes and the CRT is not as easy to probe as a Tek, so it will take me some time to get around that scope that's new to me....   

Stay tuned     

Okies... first, have you inspected the neck of the CRT in the dark? If there are carbon tracks, the arcing could be very dim and hard to see even in a slightly lit work area. Of course, you should also rotate the tube as well to be sure you have inspected the entirely of the gun assembly. Do this with lights on for safety's sake.

Also... what you were hearing could very well have been the plates singing like an electrostatic speaker if they're being driven by an arc or other intermittent breakdown voltage somewhere else in the circuit. Think about it; the CRT clamped to that big cone of a shield with the opposite end supported by a nice cushy felt ring... it's a natural megaphone working exactly the same way as a old Victrola.

My suggestion is to probe the CRT with some form of stethoscope... a condenser mic connected to a amplified PC speaker, an actual stethoscope, or even the tip of a long screwdriver with the handle pressed tight against the skull right at the ear. Of course, you'll want to keep the probing end of whatever you use well clear of any highly charged regions on the CRT.

Good hunting!

mnem
Sauron-Scope is watching you with great interest...   

[Neomys Sapiens]

When I read the entry on Ebay Kleinanzeigen, I almost smelled a rat. It turned out to be rodent free.
The title was stating: Multifunctional test tweezer - GIVEAWAY.
Well, I did write to the seller (respectively gifter) and asked politely with which amount I could support the packing and postage part of his generous offer and, unexpectedly, I got an answer.
So I have a Wuerth test tweezer, which can be used as a normal tweezer probe with a DMM, but which is also able to do a continuity test on it's own as well as put a constant current into a LED, coming to me tor the cost of a parcel and a bus ticket (below 10.-).
The device is this: https://www.we-online.com/katalog/de/TEST_TWEEZER2

I would not be averse to that happening more often to me.

[Neomys Sapiens]

potential interest in the 79

Come forward, come right forward mylady...we have nothing but premium fleecings here!
 
No, honestly...resplendent in yellow and grey, no frills, good lineage... and soon to be yours.
PM me with what it is worth to you.

[vk6zgo]

A caged nut, while a million times better, isn't really a particularly satisfactory solution either, too loose, rattley, needs a punched square hole and so on. There is, of course, a device designed to take a proper machine screw rather than some unter-fastener like a self tapping screw and it's called a rivnut:

Oh, indeed. The cagenut only excels where a sloppy fit is required. The rivnut is a much better proposition in many instances.

Just to clarify;  I never intended for the cagenut to be used by Spec in the door; pop rivets are indeed the more proper choice. My reaction to the Dragon-suggestion of the clipnut was aimed at the sad, pathetic practice of Wire-Nut-Land to use clipnuts where cagenuts are appropriate, i.e. in equipment racks. It's just, but barely so, above the practice of threading the rack strips themselves.

Tool fetischism mode:  So, what rivnut kit should I get?

Cagenuts require nice square holes to clip into, which can be problematical.
There are also several types with different depth clip parts, for different sheet metal thickness.

Whilst one type will fit both sheet thicknesses, it is sloppy with the thinner sheets, the other one doesn't fit the thick metal----you can get one side clicked in, the other side is impossible.

Add to that, in Oz, there was, at least in the 1990s, still a mix of both thread standards, so a random"box of cagenuts", as common in many workplaces, may have a mixture of types.

[TERRA Operative]

Well, my finger hit the buy button before I even could think what was happening... Roughly US$150 all up..

I see TM500, I buy TM500......... 

And it's a late one....nice!

As soon as I saw it my heart stopped, time slowed down, I saw the buy it now price was the same as the auction price, and I hit the buy button.

Now I just have to find the 012-0482-00 precision 50ohm cable, or get myself an RG-400 or RG-223 and hope for the best. Pomona make an RG-223 cable, not sure how close it is to the Tek one though. I guess I need to get a TDR etc etc setup to test cables now..... 

[TERRA Operative]

... but then I decided that the foam gasket would not be able to provide a proper seal between the door skin and the speaker frame because the speaker is 2nd hand and the gasket has already had many years of compression applied to it.

A useful thing I keep a sheet or two on hand of is EVA foam, often sold in funky colours as craft supplies.

e.g. https://www.ebay.co.uk/itm/282978430287

Just the thing for cutting that kind of gasket out of. I've used it before to replace the gasket around a tail light when the original got less than watertight, it's still doing a good job years later.

Back pre-global financial crisis when I used to spend way too much on car audio, we would use copious amounts of that weather strip foam you use around doors and windows. It's cheap and the perfect size for sticking on and around things to seal gaps and prevent vibration noise.

[Neomys Sapiens]

Well, my finger hit the buy button before I even could think what was happening... Roughly US$150 all up..

I see TM500, I buy TM500......... 

And it's a late one....nice!

As soon as I saw it my heart stopped, time slowed down, I saw the buy it now price was the same as the auction price, and I hit the buy button.

Now I just have to find the 012-0482-00 precision 50ohm cable, or get myself an RG-400 or RG-223 and hope for the best. Pomona make an RG-223 cable, not sure how close it is to the Tek one though. I guess I need to get a TDR etc etc setup to test cables now..... 

Say, do you already have a SG504 with a viable head? No? So no time for complacency! 

[mansaxel]

Cagenuts require nice square holes to clip into, which can be problematical.
There are also several types with different depth clip parts, for different sheet metal thickness.

Whilst one type will fit both sheet thicknesses, it is sloppy with the thinner sheets, the other one doesn't fit the thick metal----you can get one side clicked in, the other side is impossible.

Add to that, in Oz, there was, at least in the 1990s, still a mix of both thread standards, so a random"box of cagenuts", as common in many workplaces, may have a mixture of types.

Agree on all. But, where there's a square hole, like in a proper rack, it's the only thing worth considering.

I've got aluminium rails in my media rack at home. Very annoying, but I keep a stash of extra-deep nuts for it.

One of our machine rooms was built by a contractor who decided to fit M5 threaded cage nuts in everything. It's the only room so fitted.

[Robert763]

A bit more detail on the CMS33 repair.

I am full in Nerd-Envy^(tm) mode.  Really need to up the RF part of the lab. Also really need to get priorities right; car, spring and summer vacations.

I'm movimg on my HP 8920B   

[TERRA Operative]

Well, my finger hit the buy button before I even could think what was happening... Roughly US$150 all up..

I see TM500, I buy TM500......... 

And it's a late one....nice!

As soon as I saw it my heart stopped, time slowed down, I saw the buy it now price was the same as the auction price, and I hit the buy button.

Now I just have to find the 012-0482-00 precision 50ohm cable, or get myself an RG-400 or RG-223 and hope for the best. Pomona make an RG-223 cable, not sure how close it is to the Tek one though. I guess I need to get a TDR etc etc setup to test cables now..... 

Say, do you already have a SG504 with a viable head? No? No no time for complacency! 

I have an old style SG503, SG504 with head, SG5030 with head, and now this new style SG503.

I'm coming to the end of rebuilding the old style SG503 (just gotta chase down an issue with the 100-250MHz range not reaching 250MHz) and then I can start on finishing the rebuild of the SG504.

If I could find an SG5050 with head for a good price, I'd be so happy... 

[AVGresponding]

Cagenuts require nice square holes to clip into, which can be problematical.
There are also several types with different depth clip parts, for different sheet metal thickness.

Whilst one type will fit both sheet thicknesses, it is sloppy with the thinner sheets, the other one doesn't fit the thick metal----you can get one side clicked in, the other side is impossible.

Add to that, in Oz, there was, at least in the 1990s, still a mix of both thread standards, so a random"box of cagenuts", as common in many workplaces, may have a mixture of types.

Agree on all. But, where there's a square hole, like in a proper rack, it's the only thing worth considering.

I've got aluminium rails in my media rack at home. Very annoying, but I keep a stash of extra-deep nuts for it.

One of our machine rooms was built by a contractor who decided to fit M5 threaded cage nuts in everything. It's the only room so fitted.

Now that is true deviant behaviour!   



EDIT: Though I can easily imagine how this happens:

Engineer: "Order me some new cage nuts and screws please"
Purchasing Officer (that's what they get to be called at Northern Shithole Council): "What are those?"
Engineer: "For fitting things in racks"
PO: "Oh, ok. What are racks?"
Engineer: "mutters 'what I'll use to murder you, idiot They are what we're building. Just get me 500 M6 cage nuts and 20mm long screws to match please"
PO: "Ok, no problem, just let me ring around the suppliers for the best price" -hastily scribbles a note-

Some coffees later:
PO: "I need some cage nuts and screws"
Supplier: "Sure, how many, what size?"
PO: "Wait a moment, I have my notes here somewhere" -struggles to read notes- "Ermm, 500, umm, M...5? And 20mm screws for them"

On site, when the driver arrives from the supplier:
Driver: "Here you go mate"
Engineer: "Cheers"

Driver leaves, engineer checks order more closely and curses, then shrugs and uses what he has to hand.

[Cubdriver]

At the risk of jinxing it, I have an HP 6177B DC Current Source coming from everyone’s favorite wallet-draining site.  Scored it as the sole bidder for $50 plus about $23 in shipping.  It looks to be late 60s vintage - has the PH-163 mains connector we all love so.  It’s missing the feet, but other than that and being a bit grungy looks to be in decent nick.

-Pat