Hi Tautech,
Yes, ESR meter and HV leakage testers are on my list ! ESR short term, HV leakage mid-term... especially as I would like to design/build my own as it seems quite simple, so would be a good excuse to design something, and small enough a project that it would probably actually get completed, ahem...
ESR wise, my budget is limited so I was thinking of this 100 bucks DER 5000 hand-held LCR meter. For the price, I think its by far the best bang for the buck I can get, feature and engineering quality wise, and of course it would do much more than just ESR. With its 4 wire design/construction, it will be able to measure tiny pF range caps much more accurately than DMM's, as well as accurate low ohms measurements which I also need/want to be able to do. Still, 100 bucks is still a little steep right now, and so to get me going very quickly I am now on the verge of buying one of these popular 10/20 bucks little kit ATmega based "do it all" component testers, as they also do ESR and do a decent job at it apparently. Will also help me sort the gazillion of components I have recently salvaged, after "processing" 5 large boxes of boards.
Been meaning to buy this little tester for some time now...but somehow always finding good excuses not to... but I think I need to get my priorities straight, or else I will never get it : In the past few weeks I have felt weak and eventually spent some money for yet some more old instruments which in all honesty I did not really need... like this 2215 to start with, which cost me 60 Euros shipped. So if I don't get my priorities right, I will just pile up old gear yet not even have the basic test instruments I need. I need to balance things ! I can't justify spending money on old gear yet pretend I don't even have just 20 bucks for that little component tester.... isn't it.
Would need to make sure it can test ESR in-circuit though, or else it won't be much use. Still, I would still get one I think, to help me test/sort all my components. As far as I understand, an ESR meter basically is just an AC ohm-meter with a signal amplitude of a hundred mV or so, low enough to make sure it won't turn on/be "contaminated" by PN junctions, even old low drop 0.25V germanium diodes. Then it's up to you to implement / design it the way you like...
HV leakage tester wise... yes I definitely intend on getting one, especially as I am getting more and more fond of these old glowing Tek scopes, and even other tube based test gear ! Recently in the local ads I fell in love with an old Metrix 620 "LCR meter" / impedance bridge ! With its magic eye tube, and big black Bakelite knobs and lovely, thick engraved stainless steel dials that just ooze style and quality... I just couldn't resist, at only 35 Euros (and a seller willing to ship, for a change !), when this instrument usually sells for 150 Euros or more... I had to have it !
I know... when I bought my Tek 317 scope I promised myself it would be my first and last piece of tube equipment... and that therefore, for example, I would not invest in a tube tester. That was a year ago.... a year later, I am so in love with that old Tek scope, such a joy to look at and operate, both inside and out... I feel an addiction growing fast ! I now can't help but look at every glowing Tek ad I spot in the "local"/French ads ! " Luckily " so far, they have all been way too far away from me (usually at the other end of the country...) to make it worth the trip, both from a financial point of view (gas is horribly expensive over here, any trip over 50kms starts getting costly...), as well as from a practical point of view (my right leg hurts badly after only 45 minutes of driving, and I must stop).
But.... the other day I found a 535A scope for only 50 Euros and for once, it was not too far... though not really next door either : 200kms. So I e-mailed the guy to see if he might have the opportunity to drive part of the way for some personal or business trip he may have planned in the near future... but no answer as of now. Been a couple weeks.... So looks like even this one, will escape me ! LOL
No really it's a pain. The old 500 Tek scopes do pop up regularly over here, maybe one every couple of weeks of so, country-wide, but they are never close enough to me, and of course the sellers refuse to ship them ! Mostly because well... even if they bothered packing it, the resulting parcel would exceed the weight limit and overall dimensions that the mainstream/affordable transporters allow : 30kg max, and only 150cm for the sum of the 3 dimensions. So a 50cm cube for example... now try fitting a 500 scope, and all required packing material, into such a tiny footprint....
At least the Metrix 620 was small and light enough that shipping could be reasonably considered....
Anyway, digressing again sorry.. you know me !
So yes, a HV leakage tester is definitely on my list. It's not as urgent as an ESR meter though, and I am not aware of new/off the shelf testers (though I didn't really search that hard to be honest ...). I would love one of these period/vintage testers, but hard to come by, too expensive, and very bulky...
Given that the operating principle is simple, from what I understand (just apply desired voltage and measure/display the current using whatever form of display you like... magic eye tube, galvanometer, whatever...)... I would love to design my own... Currents involved are very low anyway, so shouldn't be too difficult to design a suitable HV supply... should be fairly easy and not take too much space at all. Should be able to all fit in a more compact/"bench friendly" enclosure than the old tube based testers... I would think. So this little project quite appeals to me...
As for Paul's LV leakage tester.... it kinda leaves me confused to say the least !
I love this guy, been subscribed to his channel for a while now, been watching every single video in his catalog. I like the design/engineering bias of his videos, and from what I understand he is an actual design engineer, so I give him credit and enjoy all the advice and tips he gives in his videos..... however, when he presented his tester the other day, I was at a loss : HOW can you test the behavior of a component, cap or anything else, at say 600V.... unless you actually SUBJECT it to that voltage ?!
From what I understand, it kinda "works" in practice, because he mostly tests 60 year old caps, so have had enough time to degrade so much that they would leak a measurable current even at only 2 or 5% of their operating voltage (especially since, AIUI, his device can measure/detect extremely low currents)... so by extrapolation, reasonable extrapolation, but extrapolation only none the less, we can safely assume that if it leaks at say 5V... you bloody can bet it will leak like mad when subjected to its multi-hundred volts operating voltage. OK, I am fine with that...
But if the cap is not that old, is only at the beginning of its deteriorating process, and only starts to leak at say 90 or 95% of its operating voltage.... several hundreds volts then.... the LV tester will not register any significant current and declare the cap good, when it is not...
So I think this LV meter is great as an INDICATOR, to help find very/blatantly faulty caps, and would be plenty good enough in practice, when working on really old caps/instruments, and I understand Paul did a lot of testing to confirm this.... but still, it's only an indicator, not an actual / reliable test of how the cap performs at its actual operating HV...
Also... the only reason Paul designed a LV leakage tester, from what I recall, is that he thought people might get zapped when using old/vintage HV testers, by accidentally touching the test leads/jacks, or forgetting to discharge the cap before handling it after performing the test. Well... I mean, if you can't even watch your fingers and think, when you are merely testing a cap on your bench... how will you survive the process of restoring/fixing the tube piece of gear that you are trying to fix, given it has HV absolutely all over the place, if you can't even watch where you put your fingers and pay attention to your own safety ?!
Hell, how can you fix ANY mains powered piece of gear, even modern stuff... given that most of them have a 240V SMPS hence with 340Vdc or so, across the main filter cap ?!
I understand Paul is from the US where every video over there, starts with "do it at your own risk, I can't be held responsible for your electrocution blah blah blah", but come on... if you work on HV equipment, well... you should not do it unless you know what you are doing ! You are not some kid that needs safe guards and babying, you are an adult who knowingly chose to work on HV stuff !
Of course I am not saying we should play with fire needlessly, so I am all for making HV testers as safe as they possibly can be, by minimizing exposure to HV as much as possible, through careful mechanical and electrical design, just like a good DMM does... but at the end of the day, if you want to test a cap at its HV operating voltage, well one way or another you will have to produce said HV and deal with it !
What next ? An insulation tester that will test motor winding insulation at 10V instead of 1,500 Volts ?!...
And what should we do about all these glowing Tek scopes ? Should there be a law that forbids selling them to "unauthorized" individuals ? I mean, ANY of these scopes have HV not just inside of course, but
EXPOSED ON THE FRONT PANEL as well !!!! I mean, the probe calibrator output can be adjusted at the flick of a knob to produce no less than 100V, for starters !! Then, among the few 4mm binding posts that populate the right edge of these scopes, you will find the sawtooth output from the sweep section, which ramps up to 175V or so !!! And this binding post is literally at your finger tips when you operate the sweep knob ! So people could get zapped easily just by OPERATING the scope, not even by opening it to mess inside of it !
Let's be reasonable...
Again, I love Paul's blog and every bit of design/engineering comments he brings to his videos.. but in the particular case of this LV tester, I really don't understand...
A great little tool, a help, an indicator, good for most practical restoration purposes of old gear, I don't doubt it, he tested it extensively and has massive experience restoring Vintage gear and dealing with these old caps.... but an actual, indisputable test instrument... it's too much of a stretch in my view
Hell instead of babbling here I guess I rather ought to work on the scope !
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