Test Equipment Anonymous (TEA) group therapy thread

[bd139]

Have you been using Chinese parts on your radio bit that keeps blowing up?

Not that bit no. That’s been legit Vishay IRF510s. Just my shitty matching network design that is doing it.

Literally the only crap parts in it are the 78L06’s and the Molex/JYK connectors (from Tayda). Connectors have been fine though. Apart from one which melted but that was my fault 

[tautech]

Have you been using Chinese parts on your radio bit that keeps blowing up?

Not that bit no. That’s been legit Vishay IRF510s. Just my shitty matching network design that is doing it.

Literally the only crap parts in it are the 78L06’s and the Molex/JYK connectors (from Tayda). Connectors have been fine though. Apart from one which melted but that was my fault 

Slap it together and if it doesn't smoke or melt it must be OK right ?

[Specmaster]

Have you been using Chinese parts on your radio bit that keeps blowing up?

Not that bit no. That’s been legit Vishay IRF510s. Just my shitty matching network design that is doing it.

Literally the only crap parts in it are the 78L06’s and the Molex/JYK connectors (from Tayda). Connectors have been fine though. Apart from one which melted but that was my fault 

Your having a whale of a time lately, blowing things up, melting things, wiping out CAL data, breaking lawn mowers, ovens anything else you want to declare now? 

[tautech]

Have you been using Chinese parts on your radio bit that keeps blowing up?

Not that bit no. That’s been legit Vishay IRF510s. Just my shitty matching network design that is doing it.

Literally the only crap parts in it are the 78L06’s and the Molex/JYK connectors (from Tayda). Connectors have been fine though. Apart from one which melted but that was my fault 

Your having a whale of a time lately, blowing things up, melting things, wiping out CAL data, breaking lawn mowers, ovens anything else you want to declare now? 

They say variety is the spice of life.

Must go now and spray some noxious Pommie import.....gorse, the bane of my existence. 

[GerryBags]

Must go now and spray some noxious Pommie import.....gorse, the bane of my existence. 

Totally OT:
If you want a completely natural, harmless (but deadly?) way to kill off gorse, you should take a look at stearic acid from coconut oil. It's also known as P-20, polysorbate-20 and Tween-20 ( ), but it's a 100% organic non-ionic surfactant that has amazing effects on plant growth. It's widely used in agriculture s a soil wetting agent, but if you add more than a certain percentage (about 2-3% by volume) you will make the roots of any plant watered with it absorb far too much moisture and causing the roots to rot.

If you use it in the usual agri- quantities (around 0.5-1%) it will stop water from sitting on the top soil and will help the plants take up water and nutrients a little better, but you won't see much of a yield increase (or bigger flowers, healthier growth) from it. If, however you get the concentration in a very narrow window around 100 ppm, or 0.1g per liter (the drop-off in the effects occur 10-15 ppm either side of 100 ppm) there is a change that occurs in the cell membrane of the plant's cells. The ionic transfer of nutrients across the cell membrane is dramatically enhanced along with both the absorbtion and retention of water. Yield, both dry-weight and wet, are increased 30-40% with some species (lillies did particularly well in this one study I found) and cuts water-cycling through transpiration by up to 400%. Given that a plant will generally only use 5-6% of the moisture it takes up through its roots, expelling the rest from stomatophores in the leaves through transpiration (the botanical version of respiration) this results in a huge reduction in the water required to go from seed to mature plant, in the order of 50% once all other factors are accounted for. Half the water for a 30% increase in weight from a 'chemical' that costs £7 a liter from natural cosmetics companies! (They use it as an emuslifier in all sorts of bath-oils and facial washes).

It also kills fungal spores, viruses, spider-mite and aphid eggs in the 100 ppm concentration by the same mechanism as that which benefits the plants so much: increasing the permeability of the cell membrane throughout the organism.

I can't link to anything much except scholarly stuff, the original study that found the 100 ppm effects (https://etd.auburn.edu/bitstream/handle/10415/1203/Yang_Xiaomei_2.pdf?sequence=1) is from 2008 and seems to have got missed for many years, although the research is starting to be replicated by academics, rather than just weird old cripples with esoteric interests (me).
Here's a paper on using at as a weedkiller: https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4904&context=rtd

Oh, and if any metrologist here  fancies working out an easy circuit/device to automate the precise mixing of 100 ppm of a gloopy liquid with exactly one liter of water they would be benefitting the whole world! I've been evangelising about the stuff whenever I can, and even when I shouldn't (sorry, I tried to bring it back on topic, but I feel like that failed )

[Specmaster]

That may well be just he's spraying, he did say after all it some noxious pommie import?

[Cerebus]

Oh, and if any metrologist here  fancies working out an easy circuit/device to automate the precise mixing of 100 ppm of a gloopy liquid with exactly one liter of water they would be benefitting the whole world! I've been evangelising about the stuff whenever I can, and even when I shouldn't (sorry, I tried to bring it back on topic, but I feel like that failed )

You don't need any fancy circuitry, just two peristaltic pumps, one huge, one tiny, on the same shaft.

[tautech]

That may well be just he's spraying, he did say after all it some noxious pommie import?

Yep, gun spot spraying and in a pasture environment. Mostly hilly country so pasture damage is something we want to minimize/avoid.
Started a 1kL tank yesterday and it's just below 1/2 now but won't get this brew gone before the weather packs up for a few days.
Been using this stuff for many years now and although I'll never eradicate it there won't be much left to mop up by my boys.
600 g/kg METSULFURON-METHYL in granulated form and needs a non-ionic surfactant to kill gorse.
There was a time we applied 20kL/year and thank gawd those days are well behind me as I'm getting too bloody old to scramble around the hills dragging 70m of hose behind me. Keeps a man fit though. 
We've (family) been at this for ~50 years and in those days the only chemical available was 245T, one of the constituents of Agent Orange.  Now banned here. The other was 24D and still widely used in agriculture today.

GerryBags
Thanks for that stuff, I'll have a good look at it but it's damn hard to beat the pricing on what we use now. The non-ionic surfactant is the most costly part of the brew @ ~NZD 17/L with the Metsulforon ~1/2 that.
It's greatest advantage has been ~3 months activity in the soil against gorse germination and that alone has given us the greatest help in the past couple of decades we've used Metsulforon. Yay, less seedlings .....every year !

[bitseeker]

This phenomenon HAS to be some relative of the "Man with two watches" effect. We need to come up with a TEA name for it...


FDDS - Flipping Digit Distraction Syndrome: When the constant flipping of the last few digits on your 4+x and 1/2 digit instrument distract you from the work you're supposed to be doing with it.

Oh YEAH!!! And it has an advanced stage condition as well... 

BDADD - Bouncing Digit Attention Deficit Disorder: When you don't hear your wife/kids/boss calling your name because you're too busy watching those digits flip on a stack of such instruments and trying to figure out the pattern; or because you just noticed that two or more of them seem to be in sync.

But wait; then there'd have to be the inverse function where this becomes a fetish...

FDDAS - Flipping Digit Device Acquisition Syndrome: When your TEA evolves such that you are pathologically driven to collect test gear with excessive extra digits just to watch them as they demonstrate entropy.

Good stuff. Added to the glossary.

[bitseeker]

I’m trying to work out if I can write something to dump and load the cal data via HP-IB. Might give people an insurance policy without having to fish out for a cal cert. Arduino jobby looks possible.

Check the forum. I recall at least two projects that resulted in tools to dump/load the 3478A cal data.

[AF6LJ]

Here is a good start.
https://www.eevblog.com/forum/repair/hp-3478a-how-to-readwrite-cal-sram/msg1296475/#msg1296475

[bd139]

Aware of the ones already out there. I don’t learn anything by using them

[med6753]

Thanks to bd139....big progress on this Tek 465. See attached schematic. The +110V supply is completely FUBAR. Zener VR1515 is shorted, so is CR1514. R1517 is burnt. I'm assuming Q1516 and Q1518 are gone. I isolated the +110V supply by lifting VR1515 and CR1516 and now the mains fuse holds. I checked TP1518 and it now measures almost 17K ohms so there's no short. And the DM44 powers up and actually works. Order going into Mouser today. There's hope for this old beast after all!   

[Specmaster]

Yes bd139 is a good egg, he did actually pinpoint the problem as well, suspected that the Zener was shorted as the 110v is referenced to the 55v line. So it looks like another 465 will be saved, well done.

[AF6LJ]

It is always a joy to see gear saved from the landfill.
 

[bd139]

Good stuff 

Transistors might be ok if the zener went short as it'd divert all the current around the transistors. Worth checking them.

Reminds me I need to swap that cap out in mine before it blows up

[Specmaster]

Good stuff 

Reminds me I need to swap that cap out in mine before it blows up

That cap looks like an iron burn, is it?

From mobile device so predictive text might have struck again [emoji83]

[bd139]

Well it wasn't there when I inspected it when I got it, I haven't been near it and is now so I'd expect that it is something about to blow. I've seen it happen before - they go high ESR, get stupid hot and then the plastic coating melts and chars. Then they blow your face off.

[Specmaster]

Well it wasn't there when I inspected it when I got it, I haven't been near it and is now so I'd expect that it is something about to blow. I've seen it happen before - they go high ESR, get stupid hot and then the plastic coating melts and chars. Then they blow your face off.

Whip it out quick and change it, wouldn't want you to be faceless. [emoji106]

From mobile device so predictive text might have struck again [emoji83]

[med6753]

It is always a joy to see gear saved from the landfill.
 

Yep, and even though there's no trace due to no +110V I'm letting it sit for a while powered up to see if any additional tants that I found before shorted decide to commit suicide. This old beast has not been treated well...now getting that musty electronics smell typical of equipment that's been stored in a damp environment.   

[med6753]

Good stuff 

Transistors might be ok if the zener went short as it'd divert all the current around the transistors. Worth checking them.

Reminds me I need to swap that cap out in mine before it blows up

R1517 is also burnt so I'm gonna change out the transistors anyway. They're cheap and Mouser has equivalents in stock. And again...thanks for your help! 

[bd139]

Makes sense 

Just took some time out to replace that cap on my 465 and cleaned the vertical pots too. Cap was knackered. I peeled all the plastic off and was left with this, which does not look healthy. Measured it at 185uF which is pretty damn low for a 1000uF capacitor.  Not going to bother to check ESR. Pots got a quick squirt with WD40 contact cleaner (not normal WD40!!!!) and are as good as new now. I was careful not to displace any grease on the shafts.

[AF6LJ]

It is always a joy to see gear saved from the landfill.
 

Yep, and even though there's no trace due to no +110V I'm letting it sit for a while powered up to see if any additional tants that I found before shorted decide to commit suicide. This old beast has not been treated well...now getting that musty electronics smell typical of equipment that's been stored in a damp environment.   

I need to get on that 475 I have stashed that works, but..........
Not quite...

I have a linear amplifier that is waiting for me to get to it...
It has that musty smell, and was stored in a shed for about ten years.

On that note....
I hate the smell of a tantalum cap burning in the morning.

[Ero-Shan]

That's what I guessed you'd do even though the GDM-8341 was a purchased new, but I suspect that it was also purchased because of the display was easier to read in your old lab corner? I wonder if the display on 3478A could be backlit at all?

That's exactly my gripe with LCDs. They're perfect for handhelds as they draw almost no current, and you can usually turn it so you can read it easily. But desktop TE doesn't need to save the last milliamp. They should at least put a backlight in it - right from the beginning.
Seeing your 3478As, it reminds me that I also have 5 of them - and never even looked at 'em. Instead, I keep buying more stuff (to be shown here soon).

[Specmaster]

I agree, its penny pinching to not include a back light, its only going to take an extra couple of mA to drive so its hardly going to put any more stress on the power supply.

I can't believe that you have 5 of them and have never even looked at them let alone used them. I have always wanted at least one of these but they have always been to expensive for my budget. Also have a HP3466A which I also love and because it has a battery fitted is my go to meter first because I don't have to put power on the stack if I just need to check something quickly.