Test Equipment Anonymous (TEA) group therapy thread

[extremgear]

Hello everyone,
New multimeter has come home .
it's a 3457A, i get it for a reasonable price, sold as faulty ( able to power and to measure in almost all range but with error code according to seller ) i actually don't know what's wrong with, front fuse is blown so no Amp measurement is possible for sure , i will open it and give you more information !

[xrunner]

Hello everyone,
New multimeter has come home .
it's a 3457A, i get it for a reasonable price, sold as faulty ( able to power and to measure in almost all range but with error code according to seller ) i actually don't know what's wrong with, front fuse is blown so no Amp measurement is possible for sure , i will open it and give you more information !

Check backup battery voltage. If low replace. Instructions are available on this forum to make sure you don't lose cal data.

[extremgear]

Hello everyone,
New multimeter has come home .
it's a 3457A, i get it for a reasonable price, sold as faulty ( able to power and to measure in almost all range but with error code according to seller ) i actually don't know what's wrong with, front fuse is blown so no Amp measurement is possible for sure , i will open it and give you more information !

Check backup battery voltage. If low replace. Instructions are available on this forum to make sure you don't lose cal data.

yes the battery is still good ( 3,02V) but i will change it anyway because it's older than me .
i opened the thing and it was pretty easy since all the screws that hold the cover were missing !
the inside look good and never touched ( i was scared about board swap but it doesn't look to be the case)
i will replace all the electrolytic caps too ( they are ok but i have them so ....) and have a look to the input filter for hidden rifa cap.

[AVGresponding]

Hello everyone,
New multimeter has come home .
it's a 3457A, i get it for a reasonable price, sold as faulty ( able to power and to measure in almost all range but with error code according to seller ) i actually don't know what's wrong with, front fuse is blown so no Amp measurement is possible for sure , i will open it and give you more information !

Check backup battery voltage. If low replace. Instructions are available on this forum to make sure you don't lose cal data.

yes the battery is still good ( 3,02V) but i will change it anyway because it's older than me .
i opened the thing and it was pretty easy since all the screws that hold the cover were missing !
the inside look good and never touched ( i was scared about board swap but it doesn't look to be the case)
i will replace all the electrolytic caps too ( they are ok but i have them so ....) and have a look to the input filter for hidden rifa cap.

What's the error code? Also, without price information, we don't know if you have earned a award...

[Swake]

Talking about Rifa caps. Got a 6038A for not too much money. It was almost certainly broken as the description was something in the trend of 'for parts, not tested'. And yes indeed... Replaced that cap temporarily with a Chinesium branded one and everything works fine again. Found six more RIFA Y caps on the same board.

[Swake]

yes the battery is still good ( 3,02V) but i will change it anyway because it's older than me.

Got a 3457A multimeter this week too. It seems to be possible to read out the calibration information over GPIB. My opinion is this is a necessary safety measure before starting the battery swap.

Have you found other RIFA caps in the 3457A than the ones in the Schaffner input filter?

[extremgear]

yes the battery is still good ( 3,02V) but i will change it anyway because it's older than me.

Got a 3457A multimeter this week too. It seems to be possible to read out the calibration information over GPIB. My opinion is this is a necessary safety measure before starting the battery swap.

Have you found other RIFA caps in the 3457A than the ones in the Schaffner input filter?

on my other 3478A i changed the battery without backing up the cal, i found a good tutorial were the person explain how to properly connect a temporary battery, but you have to be careful because it is very easy to short something.
There is no rifa caps in this meter, but the input  "Shafner " filter have some caps inside and these filter are well known to explode after few decades and it is totally molded apparently you can't change the caps inside, on mine i've removed this filter and put simple IEC socket for test purpose i will order a new Shafner filter.

[Vince]

QUESTION

I just received some dipped tantalum caps to recap a couple boards in my Tek 7603 scope as discussed recently.

I checked all of them one by one on my Cheap Chinese Tester (tm). Capacitance-wise they are all spot on despite the wide tolerance on these things, however I am slightly worried about the ESR. They read between 2 and 20 ohms roughly, with most of them being about 8 ohms.  I thought dipped tantalums were supposed to have very low ESR...

What am I missing ? Should I be worried and scrap them all, or is it just a known problem with that chinese tester, a limitation due to its very design ? Or just because the 9V battery is getting low ?.....

Could people measure some dipped tantalum on their cheap chinese tester please, to compare with my readings ?

My caps are 1uF and 2.2uF, 35Volts.

[factory]

Will check some of the NOS liberated ones I have, from the component cabinets I bought from work, should have both those values, I'm sure they will test similar.

David

[Wolfgang]

Several Ohms or even ten Ohms ESR is way too much. Either your tester is junk (try with a known good cap plus a known series resistance) or the caps are dead.

[extremgear]

What's the error code? Also, without price information, we don't know if you have earned a  award.../quote]

error code is 64, related to an " Amps function error " , the meter looks to read ok in Dc i didn't  try all the measurement mode yet.
i got it for 140 E but the shipping cost is an other story ...
it is in good shape despite the lack of screws, i already changed all the electrolytics caps but there were all good.
i will dig in it for the error code and i will give some news.

[tggzzz]

QUESTION

I just received some dipped tantalum caps to recap a couple boards in my Tek 7603 scope as discussed recently.

I checked all of them one by one on my Cheap Chinese Tester (tm). Capacitance-wise they are all spot on despite the wide tolerance on these things, however I am slightly worried about the ESR. They read between 2 and 20 ohms roughly, with most of them being about 8 ohms.  I thought dipped tantalums were supposed to have very low ESR...

What am I missing ? Should I be worried and scrap them all, or is it just a known problem with that chinese tester, a limitation due to its very design ? Or just because the 9V battery is getting low ?.....

Could people measure some dipped tantalum on their cheap chinese tester please, to compare with my readings ?

My caps are 1uF and 2.2uF, 35Volts.

My old 2.2µ 35V are 1.5ohms, and 1µ are 5ohms.

Tant beads have lower ESR than old Al electrolytics, but modern Al polymer electrolytics have a much lower ESR. In some cases, e.g. as a PSU decoupler on the output of some voltage regulators, the low ESR can cause the regulator to become unstable.

Personally I would only replace tant beads where the voltage rating is too low, e.g. 15V for a 13V PSU rail In such cases, increasing the voltage is what is beneficial; the ESR isn't that important.

[Vince]

Several Ohms or even ten Ohms ESR is way too much. Either your tester is junk (try with a known good cap plus a known series resistance) or the caps are dead.

Of course the tester is "junk", but millions of people bought it hence why I am asking if there is a known limitation of this particular tester, and ask to take comparative measurements.

That tester reads the ESR just fine on  Aluminium electrolytics with ESR in the tens of milli-ohms, but I ahve never tried it on dipped tantalum caps until now, so am trying to figure things out.

[factory]

Here is a sample of ESR for some of the NOS tantalum bead caps here, using the Peak ESR 60 (haven't got a Chinesuim tester), STC seem to be crap (based of sample of two), the ones labelled K seem the lowest.
Also checked some of the more expensive axial tants from STC, which test lower than the bead type. Don't have that many beads in 2.2uF & no axial tants with 35V rating.



David

[Vince]

Thanks a bunch Dave 

So that's reassuring then, looks like my caps read the same, and same "distribution", as your 'R' types (mine have no marking at all, just capacitance and voltage rating).
So the chinese meter reads just fine.

The 'K' type looks like it's just an 'R' type, but binned to select only the ones with the lowest values.

Interesting that the axial ones are way lower ESR, I learned something.

OK so I will just scrap the 2 or 3 I have that are  above 10 ohms, and keep the others as they your stats perfectly, so they must be just fine.

I wonder why these ESR testers give such a high value when it's supposed to be low ESR. Maybe they voltage and frequency they use does not play wel with this particular type of caps...


Anyway, I can use my caps then, phew... gonna solder them this evening and see what the scope thinks of them...

[factory]

Looking on Mouser, 8 ohms is a parameter in the search for 1uF 35V tant beads. https://www.mouser.co.uk/c/passive-components/capacitors/tantalum-capacitors/?capacitance=1%20uF&termination%20style=Radial&voltage%20rating%20dc=35%20VDC

And looking at a random AVX datasheet, for 1uF at 35V, they give 8 ohms max ESR at 100kHz and 5 ohms for the 2.2uF at 35V.

https://www.mouser.co.uk/datasheet/2/40/tap-776819.pdf

A random Kemet datasheet doesn't mention ESR.
https://www.mouser.co.uk/datasheet/2/212/KEM_T2043_T35X-1730558.pdf

I thought the 'R' & 'K' might represent the manufacturer, there isn't really enough space for full names apart from a couple of letters such as the STC branded ones. The above Kemet datasheet actually shows the 'K' logo at the end.

Edit: the 'R' might be from ROHM, they transferred the tantalum capacitor business to KYOCERA AVX last year.

David

[TERRA Operative]

Once I am awake, I'll throw a bunch of bead tants on my testers.
I can compare between the Chinese tester, a DE-5000, and a HP 4276A (including testing at rated voltage, up to 40VDC)

Stay tuned....

[AVGresponding]

I just pulled a random recovered 1uF 35v tant from my stock. 328 based tester says 2R2 and 1197nF, not sure about test f. LCR819 says 1.1545uF and 2R750 at 1kHz, and 919.55nF and 1R940 at 100kHz.
Second random (different manufacturer) 1uF 35v gives 1053nF and 9R8! with the 328, and 991.93 and 10R73!!, and 789.38nF and 8R956 with the LCR819 at 1kHz and 100kHz respectively.
Managed to find one more, looks to be the same brand as the first. 328 says 1038nF and 1R6, and 999.85nF and 2R173, and 869.89nF and 1R424 with the LCR819 at 1kHz and 100kHz respectively.

EDIT: Tested a recovered 1uF 50v Jamicon brand electro, just because: 328, 1152nF, 4R3.  LCR819, 1.0501uF, 11R0, and 817.38nF, 1R614.

[Wolfgang]

why dont you use a reference cap and try it out ?
Test instruments that just tell you nonsense are a waste of time, how ever cheap they may be.

[Vince]

Thanks for your participation people, I appreciate ! 

It's all consistent and means my caps are just fine... so I have soldered them onto the two boards of my Tek scope, job done.

Test instruments that just tell you nonsense are a waste of time, how ever cheap they may be.

Well in this case the cheap chinese tester proved to work just fine. For 10 bucks delivered it's hard to beat.

[tggzzz]

I just pulled a random recovered 1uF 35v tant from my stock. 328 based tester says 2R2 and 1197nF, not sure about test f. 4.[

The frequency is probably a red herring, both in terms of it being how the value is measured, and also in terms of being a useful measurement.

The measurement is probably done by applying a square wave via a resistor such as an SMPS outputs. The voltage across the UUT will be a step (size depends on ESR) followed by an exponential risetime (duration depends on C).

The poor man's variant is a 50ohm square wave signal generator applied to the capacitor and observed with a scope. That has the advantage that the sig gen can apply a DC offset, thus enabling measurement of MLCC's appalling voltage dependence.In

[TERRA Operative]

Here's my results from a handful of dipped tants I tested until I got bored... 

The ESR values on some of the T4-LCR ones are interesting.... possibly a function of how it tests them..

[Wolfgang]

Seems you were lucky with this one. My test procedure would be to take a known good cap with low ESR and to add resistors and then measure them. if the meter shows the resistor values as ESR, you are OK. Problems of cheap meters start with low capacitances and higher ESRs. To gauge this you can take a non-electrolytic cap (foil) and repeat the procedure.

I made some meter myself:

https://electronicprojectsforfun.wordpress.com/homebrew-scpi-controllable-instruments-with-arduino-controllers/an-autorange-cap-esr-meter-with-scpi-connectivity/

[AVGresponding]

why dont you use a reference cap and try it out ?
Test instruments that just tell you nonsense are a waste of time, how ever cheap they may be.

You think an LCR819 is cheap? Perhaps you have a spare couple of thousand euros you can give me, since such sums are trivial to you...

The point of my test was to show comparative reading between a cheap 328-based tester against a "cheap" Iso-Tech LCR 819 bench LCR meter (around €1500-2000 new). Reference caps are irrelevant; it's only important to use the same cap and see what each meter makes of it. I'm comparing meters, not caps.

[Vince]

Here's my results from a handful of dipped tants I tested until I got bored... 

The ESR values on some of the T4-LCR ones are interesting.... possibly a function of how it tests them..

Thanks Terra, I didn't ask for THAT much, you got carried away ! 

Testing many different capacitance values was interesting, as I can see how the ESR evolves / relates to that.

So looks like the ESR really is very high on low values, it's not until we get to 10uF or so that we get firmly to 1 ohm and below.

Then from there, as we increase capacitance to 100uF, the ESR drops a bit but not that much. I t bottoms out at a few tens of ohms.

OK OK.... thanks everyone for your help, that was much appreciated, I definitely learned something...

So I replaced those caps on the vertical amp board, and the readout board. Problem now is that there are so many wires and cable attached to the readout board, it's such a mess in there, that the board has  10 pin socket I can't find a cable for.... and OTHO I have a 5 pin cable that I don't know where it goes to.. so maybe it goes to that 10 pin socket but which of the 10 pins does it plug to... hmmmm.... I think I didn't take enough pics.... will check anyway. Also, that 5 pin plug is no more : its plastic disintegrated ( a disease in this scope I notice... strange), and I am left with just bare crimped terminates flapping around in the breeze, fun... no.  Did I say I hated '70s scopes ? Yes I did. Well I just said it again anyway....