Test Equipment Anonymous (TEA) group therapy thread

[mnementh]

Jeezus H. Christ a-hoppin' on a pogo stick... What the fuck WAS that...?

THAT... abomination of mixed metaphor is the OFFICIAL video for this song? They were fucking phoning it in. 

Absolutely nothing in common with the visual imagery of the lyrics, which are clearly about jet aircraft, or at least ones capable of reasonably high altitude flight, probably about bombers on a mission.

What the. Actual. FUCK.

mnem
Now I need to go scrub my brain with bleach, before that shitshow destroys a favorite part of my childhood...   

[mansaxel]

Gilmour's head has pushed further and further up his own arse in recent years. "Wish You Were Here" is the last excellent studio album they made. Other than that, "Animals" was decent, "The Wall" parts 1 and 2 are merely ok, and everything else pure repetition.

IMNSHO, yes, Dark Side and Wish You Were Here are excellent. But I also tend to put Animals very high in regard. It is the last constructively angry album, a scathing social commentary that is not introvert ranting like the following two albums with Waters. (and everything else Waters did afterwards). I'm, further, more tending to look at the post-Waters albums as somewhat directionless; a nostalgic quest lost in open landscapes where the lark ascends.  And there tended to be a RAF airbase.

Oh, and by the way, Vaughn-Williams best work is his 6th symphony. I'm specially fond of the recording by the Royal Liverpool Philharmonic under Vernon Handley. 

[m k]

In experimental food news, I have installed baked beans on a pizza. Results will be reported in due course.[/color][/size][/b]

You need to add some pieces of pineapple.

 

For someone of your culinary skills, this is an astonishing and truly contrarian comment.

Well, I wanted to improve your food experience. 

Imo, there are two possibilites as far as I can see:

- adding pineapple makes it better - win
- adding pineapple makes it not better - no worse than before

 

Because I'm having some Italian relatives, personally I would NOT add (never ever!) pineapple or baked beans to my pizza. Too dangerous!

Mine has ham and peaches.

[Specmaster]

I think I'll just leave this here.....

https://www.autotrader.co.uk/content/features/how-green-are-electric-cars?lid=8wnd63jd03fx

No comment.

[mnementh]

LOL... yeah, we discussed that one a while back too. ISTR aboot the same time as the WAGO vid...   

mnem
Have a care there, bear... getting dangerously close to politics now... 

[tggzzz]

Listening to Pink Floyd on a less than optimal audio system is pure heresy and you should also be beaten with that resistor box lamp. 

Dark Side of the Moon is the standard field test of a sound system's quality.

[Specmaster]

LOL... yeah, we discussed that one a while back too. ISTR aboot the same time as the WAGO vid...   

mnem
Have a care there, bear... getting dangerously close to politics now... 

Yeah, it's kind of odd though how these revised claims / studies / reports etc are coming thick and fast now though. ISTR that the BBC Top Gear trio of Clarkson, May and Hammond saying much the same thing years ago, in fact they said that cows produce much more warming gases, but there is no plan to replace cows oddly enough..makes you think though.

[Cerebus]

LOL... yeah, we discussed that one a while back too. ISTR aboot the same time as the WAGO vid...   

mnem
Have a care there, bear... getting dangerously close to politics now... 

Yeah, it's kind of odd though how these revised claims / studies / reports etc are coming thick and fast now though. ISTR that the BBC Top Gear trio of Clarkson, May and Hammond saying much the same thing years ago, in fact they said that cows produce much more warming gases, but there is no plan to replace cows oddly enough..makes you think though.

Wrong! There are plans to modify cows to reduce their global warming potential through modified diets, breeding and genetic engineering. And as far as replacing them goes, research into growing meat in tissue culture rather than on the hoof has been a hot topic for decades. The last few years have see many news stories of people trying meat from pilot versions of these tissue culture technologies.

[Specmaster]

GM burgers, yuck. Not that I particularly approve of animals giving up their life to feed me, don't get me wrong, I'm not a Vegan though

[bitseeker]

WNR

The WNR defines the ratio in dB between the wanted power [W] over the needed power [N] for a device that can/should be purchased or it is already purchased.




TEA members present always high levels of WNR, generally above 20dB.
Generally speaking the WNR and MWC (money wasted coefficient] are in direct proportion.

Good one, Zucca! Added to the Glossary.

[Vince]

Tek RM17 repair update

So now I am left with the last major problem : the 3 " AC ONLY " ranges, 50mV to 10mV / DIV... but I have a clue now as to what it might be ! 

I looked at the schematic in search of what these AC ONLY ranges might have in common... at first I failed, because I was following a red herring again : thinking well, they have " AC ONLY "in common, so must be the AC coupling cap ?!    But no, AC coupling works fine when I try it on all the other ranges.

Then the plain obvious, "right there you idiot ", eventually struck me : it's nothing to do with being  " AC ONLY " ! That was misleading.
What these AC ONLY ranges have in common is that... they are the 3 most sensitives ranges, and so are the only ones that route the input signal through the PRE-amp !

So... my problems must lie in the pre-amp, so I shall be probing in there shortly ! 

OK so now the amp is fixed, now the attenuator is fixed... let's now fix that preamp. So been working on that this evening.

Has 3 problems I can see :

1) Amplitude is way too low, like 3 to 5 times.
2) Trace moves up and down randomly, it's a sick boat.
3) When it moves, it's often accompanied with huge amounts of noise / scratchiness, like a dirty switch or something...

2 and 3 could be a pain to diagnose, so I decided to first work on problem #1, the low amplitude, as it seemed it would be easier to diagnose / work on...

TL;DR : still not fixed and no, it's not easy 

So, schematic of the pre-amp below. Fasten your seat belt.

First I checked the output of the pre-amp tube, V154. I should be getting 54V, I get half that, 28V. Replaced the tube, no joy. This bugger, a type 6CB6, is unique to the type 317 ! And each 317 has only one of these. So I am glad I have 7 type 317 in stock...
So, I tried another tube still....still no joy. Replaced a third time... still no joy. Always get 28V...

So OK, tube is not at fault, let's see what's around it. Check power supply, plate voltage. Should run off of 175V, I get 120V ! 
Yes... Murphy... the one time I don't measure power rails first.. is the one time that they are bad. 

So... this power rail, as often for a delicate pre-amp, is a local supply that powers solely the pre-amp. This is done with a triode, V163A, half of a 6DJ8. It runs from the 300V rail, and via a voltage divider (also powered from the 300V supply), R167 & R168, 150K and 200K respectively, drives the grid of the triode. So I replace that tube... still get 120V 
OK so I check the voltage at the voltage divider.... 120V ! 

So the triode was outputting 120V because... that's what it was being asked to do ! 

So the voltage divider is bad then. I checked both resistors, they are good. Eh ?! 
Uh...... what gives ?

Only explanation I can come up with is : schematic shows a little 5nF cap, C166, across R168, the bottom leg of the divider. So if that cap was say, leaking a bit, it would indeed lower the voltage of that divider. So let's find this cap... uh..... can someone tell me where it is ? For the life of me I can't find it ! 
There is a similar cap on the anode of the tube, it's a small brown Z5U disc ceramic cap. There are a few of these in the area but... I just can't find the one connected to that voltage divider !
Maybe it was not implemented on my particular scope but... I doubt it. It serves a purpose here... I think. I am not sure Tek would have deemed it wise to remove it.

Also, when I measured the voltage on the divider, hence across that cap, assuming it's indeed there somewhere.... I noticed that the voltage is NOT stable. The 300V rail is stable, but not the divider output.
I also noticed some capacitive effect maybe : when I put my probe on the divider/cap, I get say 115V, but it immediately starts dropping, slowly, and jerkily, and wonders about. It can go down to 112V every now and then. But... if take my probe off, wait say 3 seconds, then apply it again... I read 115V very briefly then it drops again... Like the impedance of my DMM was stealing some current from that cap and playing havoc with it. Something like that. Just a gut feeling really 

So... I do need to take this scope apart until I can find this cap, hoping it is there indeed. My only hope : the output of the divider is on a ceramic strip, from which two wires bugger off. One goes to the tube, but the other I can't see where it goes, it merges into a little harness and I can't follow it, don't know where it goes. 

So... my only hope is to persevere and try hard to trace that wire... it's my only hope... I MUST find where it goes !!!! 

[25 CPS]

Legacy is forever.

I’m sitting in a Tim Hortons with a laptop and a coffee installing some software to try to get some automation happening with my portable kit beyond what I’ve been doing with the wireless adapters and my tablet and managed to catch this inconsistency with the branding in the installer:

[Vince]

EDIT : hmmm just got and idea.. maybe I could disconnect that mystery wire that goes to that mystery cap.. hence taking that cap, out of circuit, leaving the divider alone... If my cap theory is correct, then the output of the divider should now go back up to 175V where it should be....

But almost 1AM, time to go so sleep. I will try my idea tomorrow...


Good night people.... 

[Cubdriver]

Vince, if that 0.005 uF cap is intermittently breaking down it would certainly play havoc with the regulator.  Nice work with your troubleshooting and documentation of it!

-Pat

[25 CPS]

Success.

First test was with my U1272A via USB:



I've never used a USB cable with any of my meters before, just the U1177A and U1117A Bluetooth dongles to throw data back to my remote logging display or iPad.  I finally got out one of the cables that I had on hand included in one of the kits I bought and tried it out, but was a bit disappointed with how little strain relief there was where the cable exits the bottom of the IR interface housing.  I didn't really dig into it much to see if the tilt stand takes care of that, just satisfied that it was logging the ambient noise on AC volts.



Next test was the U1733C LCR meter.  The software install for this was a bit more involved since it required version 15.5 or higher of the Agilent/Keysight IO Libraries as a prerequisite to the "Data Logger for Agilent Handheld LCR Meter (U1730C)" installer being run.  Once installed, the desktop icon's labelled as that complete with an icon showing the LRC meter in the old colours.  I just did an open and short with the included test leads and manually logged it to verify the whole thing worked.  Interestingly, the USB cable for this one is different from the USB cable for the multimeters.  Why?  The connector is also symmetrical so it can be plugged into upside down without any mechanical interlock to try to prevent that.  Luckily there is a label on the connector stating which side is up...

I haven't tried any Bluetooth connectivity to the laptop yet or any of the other meters in my portable kit.

I also haven't tried the insulation tester.  It's a shame Keysight discontinued the insulation testers.  It's a shame Keysight's become so prickly to deal with but I'll cross that bridge if/when it comes up for me.

[Brumby]

In experimental food news, I have installed baked beans on a pizza. Results will be reported in due course.

Point 2. With that combination you are gonna have some nasty farts. Glad you are across the pond. 

I'm glad he's in a different hemisphere!

Results will be reported... 

I'm sure they will.  (Good word choice.)

[Saskia]

the postman just rang. twice ...

Got a Keithley 2000 in the mail. Sender information plus serial number intakt. boots wo errors. Selftest gets to 400, then asks me to insert 4 wire short which I don't have. Last calibration was in 2010. Cosmetically it looks a shitload better than the 2700. Display ok, no covers missing.

cost was 155 Pesos incl postage

improvised wrt shorting ( it's not rocket science).
passes self tests.
I guess 155 for a working K2000 is fair. Now I have too many DMMs ...

[vk6zgo]

Pineapple and Bits o' Pig are a taste combination made in heaven... mixed with any form of tomato sauce, not so much.   

mnem
and fuck anchovies. with a shovel.   

I used to buy Pizzas from "Grumpy's Pizzas--service with a snarl".
One of my favourites was a Vegetarian Pizza with added prawns (not shrimps!). The lack of other meat allowed the prawn flavour to shine!

[vk6zgo]

GM burgers, yuck. Not that I particularly approve of animals giving up their life to feed me, don't get me wrong, I'm not a Vegan though

Don't like their utes, either!

[capt bullshot]

improvised wrt shorting ( it's not rocket science).
passes self tests.
I guess 155 for a working K2000 is fair. Now I have too many DMMs ...

Congrats, this is really a good price tag.
There's no such thing as too many DMMs ...

[mansaxel]

I might have to stray from the true Path pretty soon; a -- by the looks of it -- very good condition Soundcraft Series 200 has showed up locally. (at least in-country) This is the mixer I spent the 80s drooling over. It had TWO effects sends, and TWO foldback ones! A surge of nostalgia is flowing here.

Also, it being 16:4:2 is a lot bigger than the current mixer which is 10:2 and only has one send pre and one post. The venue I'm helping out pro bono do of course have an iPad controlled desk, (more like a shoe box) but 100mm Alps faders is still a thing of beauty.

[Neper]

160 mm rulez.

[Specmaster]

Pineapple and Bits o' Pig are a taste combination made in heaven... mixed with any form of tomato sauce, not so much.   

mnem
and fuck anchovies. with a shovel.   

I used to buy Pizzas from "Grumpy's Pizzas--service with a snarl".
One of my favourites was a Vegetarian Pizza with added prawns (not shrimps!). The lack of other meat allowed the prawn flavour to shine!

How the hell can that pizza with prawns be classified as a vegetarian pizza 

[tggzzz]

Pineapple and Bits o' Pig are a taste combination made in heaven... mixed with any form of tomato sauce, not so much.   

mnem
and fuck anchovies. with a shovel.   

I used to buy Pizzas from "Grumpy's Pizzas--service with a snarl".
One of my favourites was a Vegetarian Pizza with added prawns (not shrimps!). The lack of other meat allowed the prawn flavour to shine!

How the hell can that pizza with prawns be classified as a vegetarian pizza 

"Vegetarian" and "organic" are only defined by the relevant (religious) text. Hence there are many definitions to choose from.

[Brumby]

One of my favourites was a Vegetarian Pizza with added prawns (not shrimps!). The lack of other meat allowed the prawn flavour to shine!

How the hell can that pizza with prawns be classified as a vegetarian pizza 

Read the statement... "Vegetarian Pizza with added prawns"