Test Equipment Anonymous (TEA) group therapy thread

[Kosmic]

Thats Murphy for you, always gets his oar one way or other, bastard.

Talking of Murphy .... that ain't a capacitor any more 

Try at lower frequency just for fun. can you do 100hz?

[mnementh]

Oh dear... is that the juicy-juice filter out of your new-to-you 6294a...?

mnem
moo...?

[AVGresponding]

31 quid from Mouser 

I'm not substituting it for the same part. Too much cash.

What're the specs?

[Cerebus]

I'll just leave this here and see what reaction it gets, I think its disgraceful.

https://www.bbc.co.uk/iplayer/episode/m000n1xp/panorama-test-and-trace-exposed

I have't bothered to watch it, too busy just at the mo., but the blurb with it tells you everything you need to know:

Panorama hears from whistleblowers working inside the government’s new coronavirus tracking system. They are so concerned about NHS Test and Trace that they are speaking out to reveal chaos, technical problems, confusion, wasted resources and a system that does not appear to them to be working. The programme also hears from local public health teams who say they have largely been ignored by the government in favour of the private companies hired to run the new centralised tracking system. As Panorama investigates, it has left some local authorities questioning whether local lockdowns could have been handled better or avoided altogether.

i.e. Government competence at it's usual.

Your task: Find your arse, you may use both hands. You have one week.

Government action: Two weeks later they have finally hired an "arse finding" consultant from their old boy's network, and said consultants are arguing amongst themselves about what colour gloves to use, the minster responsible has enacted secondary legislation to give himself powers to prevent citizens from finding their own arses (using some highly dubious legal justification for using emergency powers to do so without parliamentary scrutiny or voting), has arranged for some of the emergency government stockpile of arses to be delivered to his constituency home,  his country mansion (with duck moat) and his in-laws house, and has promptly gone on a "fact finding" trip to the Bahamas with his 21 year old blonde secretary. Meantime the people at the coal face are saying "We know where our arses are you idiots, arse location is not the problem here".

[capt bullshot]

Some random stuff picked up from scrap:

[bd139]

31 quid from Mouser 

I'm not substituting it for the same part. Too much cash.

What're the specs?

Nothing particularly spectacular other than ripple current.

Locating substitute now.

[factory]

31 quid from Mouser 

I'm not substituting it for the same part. Too much cash.

What're the specs?

So £32 for the HP power supply and £31 for a replacement cap, I'm guessing it's the 1000uF at 100V.
I've got a parcel waiting here from Llandudno too, will see if it's also covered in Dieseasel later.

David

[AVGresponding]

31 quid from Mouser 

I'm not substituting it for the same part. Too much cash.

What're the specs?

Nothing particularly spectacular other than ripple current.

Locating substitute now.

I only asked because I might have a spare Aerovox 10mF/100V.

Those are rated pretty high for ripple iirc.

[Robert763]

Open, Short, Lord ?!? 



Not sure what the "Lord" will look like on the VNA 

Those look like thay mght be good to a few MHz
I don't suppose it came with any coefficient data.

[bd139]

I only asked because I might have a spare Aerovox 10mF/100V.

Those are rated pretty high for ripple iirc.

Interesting. This needs to be around 1mF though which is the issue. All the capacitors these days are a hell of a lot smaller.

So evaluation of the rest of the supply suggests healthy. No signs it has ever been brought up by accident on 230v on the 115v taps which is good. All the other caps test good for ESR. The only problem is this one is open circuit. I did actually test it first with my ESR meter which the needle didn't even move on 

So I've got this big hole and need to get a smaller capacitor in it.



I've done this before which was a bit overkill but worked nicely so it may be something along those lines:

[Robert763]

31 quid from Mouser 

I'm not substituting it for the same part. Too much cash.

What's the value and voltage supposed to be? I may have something yu could use.

[bd139]

1000uF 100V. ~ 21.8mm pitch screw terminals.

I did actually have a dig around in the junk box and see if I had something I could bodge in to test it actually works before I invest in the right capacitor to be honest but I'm actually nearly out of electrolytic capacitors at the moment  .

Nearest thing I could find was two rather ancient 150uF 75V units in series. That'd give 75uF, hopefully enough bulk for it to power up and not sink any major current. Thoughts?

Edit: found Sprague capacitor databook http://www.bitsavers.org/components/sprague/Sprague_Aluminum_Capacitors_1990.pdf

[Cubdriver]

@Neomys Sapiens:

Are these crimping pliers any good? I want them for crimping BNC connectors on RG316 and RG400 cable

TOOLCRAFT PZ-505 818645

https://www.ebay.com/itm/392718039113





Plan B would be a Knipex 97 52 50:

https://www.ebay.com/itm/353127955942

R U kidding me? Tooolcraft? Blech!

On the other side, that Knipex is not cheap. For that price you could score a M22520/5-01 with a fitting insert, if you forego cosmetic perfection.  I even saw one (without insert) below 100.- on ebay.de.

One of the few SUCCESFULL aquisition in the last month were the fixed-die Suhner crimp pliers for both 50R and 75R BNC/TNC. The seller did offer one again, but I can't say whether there are still more. I payed around 10.- for one and 20.- for the other.

If you need the BNC/TNC inserts for the M22520/5-01 or the M22520/10-01 identified by Mil and Mfg. ID, just drop me a note.

I already thought that you will pull me by the ears because of the toolcraft. 
But in my defense I was left unsupervised I liked the flexibility of it.

I had a look at the pliers from Daniels, very nice! Thank you!

But I think I'll go after the Knipex because I can use it for RG58/59/400 RG174/316 the same time without changing the crimping inserts.

Dammit, now there's another 'spensive tool I want!   

-Pat

[tautech]

1000uF 100V. ~ 21.8mm pitch screw terminals.

I did actually have a dig around in the junk box and see if I had something I could bodge in to test it actually works before I invest in the right capacitor to be honest but I'm actually nearly out of electrolytic capacitors at the moment  .

Nearest thing I could find was two rather ancient 150uF 75V units in series. That'd give 75uF, hopefully enough bulk for it to power up and not sink any major current. Thoughts?

Edit: found Sprague capacitor databook http://www.bitsavers.org/components/sprague/Sprague_Aluminum_Capacitors_1990.pdf

I'd instead consider pulling the caps voltage rating back some closer to what it will really see without such a large derating as lower voltage rated caps generally have better ripple spec.

[mnementh]

My vote is for 5 220uF mounted radially on a PCB with some PC mobo standoffs nutted & soldered to it.

mnem
 

[bd139]

Might be right there. According to this the specifications are:

1000uF +50% -10%
100V, 150V surge
low ESR
Apparently will handle up to 24A of ripple current at 120Hz (yeah right)

Traces are snakey as fuck so impedance control isn't a major issue so a bank of smaller ones might work nicely. PCB time, now I have some transfer film!

[Robert763]

1000uF 100V. ~ 21.8mm pitch screw terminals.

I did actually have a dig around in the junk box and see if I had something I could bodge in to test it actually works before I invest in the right capacitor to be honest but I'm actually nearly out of electrolytic capacitors at the moment  .

Nearest thing I could find was two rather ancient 150uF 75V units in series. That'd give 75uF, hopefully enough bulk for it to power up and not sink any major current. Thoughts?

Edit: found Sprague capacitor databook http://www.bitsavers.org/components/sprague/Sprague_Aluminum_Capacitors_1990.pdf

I have a 1000uf 100V (125V surge) high ripple capacitor but terminal spacing is 1/2" and it's 3.2" long if that is any good for you.

[bd139]

Unfortunately too long

Thanks for looking however. Appreciated 

[Robert763]

Yeh, that is a bit of an odd size, plenty stubbie ones with higher voltage rating but not enough C.  Five 220uF or Four 270uF in parallel on a PCB shoud be OK. I'd go for more than 100V rating with modern caps, 160V wire ended should be OK 200V "snap-in" would be extra conservative

[bd139]

Sound sensible! Designing something shortly.

I bit the bullet and decided to fire it up with no load just to do a quick check to make sure it's not completely fecked before I throw any time at it. I've jumpered the board for 230V operation, put the correct fuse in it (not the 5A fuse it had in the holder on the front already  ), stuck a UK plug on it and tack soldered two small caps in series across the cap hole. I am not proud of this. The caps were ESR and capacitance checked first



Fluke 25 is across the capacitors (just to check the 46 year old Sprague 39D's aren't going to explode) and the 8060A is on the output. It works! (Excuse the mess - too busy pissing around with power supplies to clean up tonight)



Going to reassemble it now and research the aforementioned "mini-capacitor-bank" idea.

On a side note, the 8060A feels cheap and flimsy after you've been using a Fluke 25 for a couple of weeks 

[Kosmic]

Thats Murphy for you, always gets his oar one way or other, bastard.

Talking of Murphy .... that ain't a capacitor any more 

Try at lower frequency just for fun. can you do 100hz?

Did you check at 100Hz or 120Hz ? You should not try to measure high value capacitor like that at 200Khz (my understanding of how your LCR meter is currently setup).

[bd139]

Yeah it was checked at low frequency on Peak LCR45, homebrew ESR meter and shitty uni-t meter. The capacitor is completely open circuit

[Kosmic]

Yeah it was checked at low frequency on Peak LCR45, homebrew ESR meter and shitty uni-t meter. The capacitor is completely open circuit

Ho ok

[Specmaster]

89.4V eh, 100V rating caps would be pushing it a bit, 150V I think would be a wise choice.

[Saskia]

set up a debian machine to bring a completely dead WD mybooklive back. Currently formatting ...