Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Only thing that doesn’t happen for is kidneys. You never have a spare one when you lose the first two 

[Cerebus]

Which is why it's important to have genetically close relatives that you don't really care about. It helps if they live somewhere healthy too. Perhaps with clean mountain air and water? 

[bd139]

Got lots of those sorts of relatives

Last 427A post of the day. Battery eliminator stuck down with VHB tape. One job done at least. Feel like I'm getting somewhere.



Project queue is nearly large enough to keep me going until end of year. Have two more hamfests to hit: MKARS and Croydon. Will see what garbage I collect at those. Croydon is notoriously shite though.

[mnementh]

Oh, BD revived his old avatar, phew !

I like it very much. The other one looked ugly and scared me somehow, brrr....

I saved a copy just for you, Vince...

mnem
 

Heh... Vince brought a gun to a rocket fight...

mnem

[25 CPS]

The divider network is designed to sink 7mA which is above the 5mA minimum regulation on the NS LM317T datasheet. The 13mA load is in addition to that

I saw that divider and guessed 5-10mA, plus load. But I do a lot more dead-bug fugly than most folk. Is the voltage differential enough that you even need a heat-sink at 20-25mA?

mnem

I was over-engineering it to start with on the heatsink side of things. The thing has a 200 ohm dropper resistor in series with it which burns off most of the drop already so there was no need to make the LM317 drop it. I will remove it when I stick the regulator down. So yep, not needed. I'd rather not have it in there as it adds mass to the poorly mounted LM317 anyway which isn't great when it's not nailed down 

The actual HP 427A takes only 1mA of current on DC and AC ranges and up to 13mA on resistance measurements and most of the latter is the measurement current source. It barely sips the juice. Quality engineering 

That definitely explains how HP got the long running time out of the battery that's referred to in the manual.  I've got two 427A in my collection that are on the shelf but I don't remember if either of them had the battery eliminator option.



I'll pull them down and look at them later.  The test equipment projects I'm working on right now are on hold for today.  I'm going to visit one of the relatives this afternoon and evening.  Test equipment got bumped yesterday evening and this morning by the fact that the awful neighbour next door appears to have gone out of town for the long weekend which gave me an chance to do some work in the corner of the yard near her place in peace.  It generally isn't a problem when she's around but the whenever the opportunity to do so without having to walk on egg shells comes up, I take it.  Poor neighbour's been having a rough time.  I continue to exist, the other neighbours next to me continue to exist, and to really rub salt in the wound, the house on the other side of her sold to a multigenerational ethnic family.

How do you annoy a racist, homophobic, islamophobic neighbour with test equipment?  The multimeter continuity beeper.  The last time I had to chase down opens in the outdoor lighting circuit, the continuity beeper was the giveaway that I was in my back yard that sent her back inside in a snit.  I will be holding off doing that specific work until she's back.

[Saskia]

Which is why it's important to have genetically close relatives that you don't really care about. It helps if they live somewhere healthy too. Perhaps with clean mountain air and water? 

oh, a spare parts farm ...

[Brumby]

Ah, yes ... The Island.   

[mnementh]

On the Bench Today: G'rilla Molested 54621D

For good or evil... there it is. A fucking 2 dollar battery. Made with a 12-dollar spot-welder. 

A bored tinkerdwagon is a dangerous thing... but if that coin cell doesn't spontaneously combust sitting on that tile overnight, I'm gonna put it in that 54621D. Fuck DigiKey and their stoopit Canadian account BS...

mnem

So I wasn't exactly comfortable just leaving that coin cell lying there on my bench, even if it was on a nice fireproof surface; visions of it exploding electrolyte all over my bench made me think twice. So I put it in a double-walled stainless steel mug to contain any potential KABOOM...! and covered it with the biggest, heaviest, brickiest thing I had handy, short of going out to the shed and grabbing a cement block. 




C'mere, ye little gawddammitt...




...and all soldered in (sorry-not a single in-focus pic); yes, I used my Metcal for its intended purpose here. Time to scrub with IPA.




Oooooh... shiny.




Still juicy...




Once you get to this point, these 546xxx scopes are a relatively simple 3D jigsaw puzzle. A pleasure to work on, really.




One thing I do make sure of, whenever I'm doing a machine that has screws through it as well as on connectors on the edge: once the board is installed and all the connectors fed through exactly where they belong, I install all the screws through the PCB, then snug them down and back them off 1/4 turn.




This ensures that when I tighten the nuts and screws on the edge connectors, the PCB can self-align so there's no stress on the connectors or PCB. Only then do I tighten the PCB screws, using the usual criss-cross pattern. Unless, of course, there is a special pattern required due to heat-sink mounting, etc.




Don't forget to put this little wire in and press it down into the slot, or you won't have a Cal signal on the front panel. Yes, it is a insulation displacement type connector.




Here it is all assembled and waiting for that replacement CDM-7SX191 from fleaBay. If they'd posted its condition honestly it would have looked like this, and I'd never have had anything to bitch aboot. 

mnem
 

[BU508A]

The Signal Path made a video about powering the whole house from battery.
I don't know if Zucca has been involved...

[mnementh]

...I fucking hate moving.       
Now I have a spare 300€ transformer   

Awww fuck, Saskia... I swear I was only joking on ya yesterday... I didn't mean to jinx ya... 

mnem
what's that red dot moving up my chest...?

[mnementh]

...How do you annoy a racist, homophobic, islamophobic neighbour with test equipment?  The multimeter continuity beeper.  The last time I had to chase down opens in the outdoor lighting circuit, the continuity beeper was the giveaway that I was in my back yard that sent her back inside in a snit.  I will be holding off doing that specific work until she's back.

Seems to me you should do your work exactly when you know she'll be there, and make sure you keep a bullhorn keyed up as close as you can to the meter while you're at it. Business end pointed directly at her, of course.

mnem
 

[Cerebus]

I wouldn't normally mention "foot the ball" on here, or even be interested, but the Women's Euros has just finished. I just thought that I ought to warn the Germans that they ought to avoid the media, and stick their fingers in their ears until they've had a stiff drink first to prepare themselves. 

[worsthorse]

Welcome back! When you vaporized without warning, I feared the worst... but I was having my own "heavy doses of IRL" at the time and I guess I let it slide. 

I certainly am glad to be wrong. Hope you're still with that SO who so delightfully kept your home looking like a advert for Flowerama...

mnem
Tonight, the zeros 2465s were singing for you...

GA Mnem, happy to say that I haven't been vaporized though there may have been one close call in there somewhere. SO is still filling the house with flowers and teaching others how to do that, too, so it is pretty much flowerama all the time here.   I am still doing my "mostly solo" thing, too, but do make the occasional attempt to play well with others. 

And as for local... yes, still in the Pacific Northwest, though looking for a house with some shop space outside the city and all the madness. 

[mnementh]

Good lord... it's a actual, factual Land Yacht. Of course it's special-made just for woodchucks with more money than brains just so they can gang up on Bambi... 

mnem
Ya cain't make this shit up...

[Saskia]

was indeed (against all odds) contacted wrt the missing ball launch gun for the T2 (plus an audio board).
There might be additional spare parts coming my way (which would be great, because I might finally get my act T2 together ...

promised my daughter a watch if she managed to finalize her training (bio lab technician) with good grades. Would be a Rado ceramics watch, so it would be something to actually desire ...

[mnementh]

Welcome back! When you vaporized without warning, I feared the worst... but I was having my own "heavy doses of IRL" at the time and I guess I let it slide. 

I certainly am glad to be wrong. Hope you're still with that SO who so delightfully kept your home looking like a advert for Flowerama...

mnem
Tonight, the zeros 2465s were singing for you...

GA Mnem, happy to say that I haven't been vaporized though there may have been one close call in there somewhere. SO is still filling the house with flowers and teaching others how to do that, too, so it is pretty much flowerama all the time here.   I am still doing my "mostly solo" thing, too, but do make the occasional attempt to play well with others. 

And as for local... yes, still in the Pacific Northwest, though looking for a house with some shop space outside the city and all the madness.

Sorry... I didn't mean that you'd been vaporized... but rather that you had disappeared like a vapor. Old IRC phrase; means you need to leave right away and don't want to or can't explain why.

mnem
/me is *~vapor~*

[factory]

Quick HP 34750A DMM update, removed the shorted 2200uF (C39) & burnt rectifier diode (CR29), cut out the carbonized PCB section under the diode. I fitted my last axial 2200uF and a salvaged 1901-0028 diode, added a link underneath for the missing PCB trace. If I can get this working, I'll fill in the hole & do a better trace repair.







Powered up & noted the display came on, this shouldn't happen with no snap-on module attached, apparently I hadn't seen the three bodge links on the 50way Centronics connector.    These wires links were promptly removed & the test card was fitted to measure the PSU rails.



They measured in at;
+5V = +4.93V
+12V = +11.94V
-12V = -11.38V
 
Tolerance is ±0.25V for the +5V and 2% (±0.24V) for the ±12V rails, looks like the -12V supply needs more work.



Thought I would grab the other 34750A and check the ±1V reference voltages with the test card, one is defective in that one, not much I can do as it's a custom hybrid, so I now have two dead DMMs with reference problems, great. 

A little searching on here later on, I found pictures of another 34750A, but this has discrete reference PCB fitted instead on the custom hybrid, this is shown on the board, but hard to see, sadly no circuit diagram for it (free pdf), need to find another manual maybe.   

https://www.eevblog.com/forum/repair/wandering-reading-on-vintage-dmm-hp3470-(hp34750a-hp34702a)/msg3790883/#msg3790883

Here are some close up pics of the removed Centronics pin & drilled hole, next to the input from the snap-on module, mentioned earlier.


David

[mnementh]

Jaycar Electronics is moving their warehouse and they had a clearance last Thursday, Friday and Saturday.  I went on the first and last days.  Met Dave on the first day ... He's done a couple of videos about the experience.

To see what I scored - and the damage - have a look here: SYDNEY: Jaycar Relocation Sale

Holy fucking asscrackers! There's Jammy Git and then there's "stolen by the palletload". That score could make somebody a decent living for a couple years in the right market...

mnem

  (sorry Vince... nothing else really fits )

[Vince]

[bd139]

Holy shit. I'm in the wrong country again 

[mnementh]

I wouldn't normally mention "foot the ball" on here, or even be interested, but the Women's Euros has just finished. I just thought that I ought to warn the Germans that they ought to avoid the media, and stick their fingers in their ears until they've had a stiff drink first to prepare themselves. 

Peeked in on the highlights reel... damn; that drive where Kelley put it away in OT looked like a Rugby scrum!

Only when she peeled her shirt off and twirled it around afterwards, I didn't wanna hurl... 

mnem
 

[mnementh]

   

mnem

[tggzzz]

Croydon is notoriously shite though.

Well, yes[1]. But what about that hamfest?

[1] Parents dragged me around there shopping when I was a kid. Two good things did come out of it: Tangerine Dream's Richochet (you can hear me if you listen carefully), and my Artemide Milano

[Vince]

   

mnem

[Squarewave]

Went to the Chippenham hamfest Radio Rally. Put some treasures in the car, but couldn't be bothered to try to sell anything in a field in the drizzle.

One bloke had a three Tek2712 and two Tek492 21GHz spectrum analysers. One of the former was shown working on a pure sine wave inverter; the display was just about visible. One 492 had a broken blue screen shield and was missing a handle, which is essential for that lump of metal. Said he would sell them for £300, but hadn't when I left.

Didn't get much. A couple of metal enclosures for £1 each, yet another Cropico resistance box (cal ran out in 2014) all resistors measure OK, and some banana plugs.

£300? Some people are dreamers! Wanted to go to this Rally, but didn't manage to get down there today.