Author Topic: EEVblog #365 - ESR Meter Bad Cap Monitor Repair  (Read 45025 times)

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Offline Slobodan

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EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« on: October 06, 2012, 08:01:56 pm »


What is the purpose of those parallel solder lines on the ground plane?
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #1 on: October 06, 2012, 08:05:12 pm »
What is the purpose of those parallel solder lines on the ground plane?

To lower the trace resistance. I have done several videos on this.

Dave.
 

Offline midasgossye

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #2 on: October 06, 2012, 08:28:26 pm »
How expensive are ESR meters and are there specs you have to watch out for?
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #3 on: October 06, 2012, 08:31:26 pm »
What is the purpose of those parallel solder lines on the ground plane?

To lower the trace resistance. I have done several videos on this.

Dave.

Ah, yes. I have seen those videos, but I don't understand why they don't just "flood" the whole ground plane with solder instead of making those parallel lines.
 

Online firewalker

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #4 on: October 06, 2012, 08:36:56 pm »
EEVblog #365 !!! "One year" of EEVblog videos.

Alexander.
Become a realist, stay a dreamer.

 

Offline notsob

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #5 on: October 06, 2012, 09:24:26 pm »
"later model" bob parker design ESR meter link
http://www.anatekcorp.com/blueesr.htm

and the older model
http://clientes.netvisao.pt/greenpal/evb1.htm
 

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #6 on: October 06, 2012, 10:52:44 pm »
Ugh - Samwha. Samwha caps are in no way to be considered good. They had a consistent 1-2 year manufacturing defect with their WB, WL and  MK series capacitors. This killed loads of Samsung and LG TVs. They are still dying - just a couple of months ago I picked up a 40" Samsung LCD TV with three bulging Samwha.
 

Offline SeanB

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #7 on: October 06, 2012, 11:10:36 pm »
Just stripped a 1997 made Samsung 24' CRT monitor - died from LOPT failure after 15 years of use. Uses a lot of Samwha caps inside, they are all still good, or at least are not bulging.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #8 on: October 06, 2012, 11:33:51 pm »
LG stands for Lucky Goldstar. 'Life's Good' is their slogan. Get it right!  :-\

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #9 on: October 06, 2012, 11:42:41 pm »
Just stripped a 1997 made Samsung 24' CRT monitor - died from LOPT failure after 15 years of use. Uses a lot of Samwha caps inside, they are all still good, or at least are not bulging.

I think it's mostly their newer ones - beforehand they were owned by Samsung then got spun off - maybe lost some key talent or just a consistent manufacturing defect.
 

Offline DL8RI

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #10 on: October 06, 2012, 11:51:19 pm »
Hi Dave,

I saw your videos on repairing these Monitors and I have done this several times... and I've a little question...
This tool you use to crack the clips open... how is it called? (seems to be some chisel for medical use?!)

I was always fighting with those stupid cases not to ruin the clips and the plastic-case itself. This tool seems to be quite handy (more than a knife, screwdriver, whatever ;) ).

73 and thanks,
Martin
 

Offline miceuz

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #11 on: October 07, 2012, 12:01:30 am »
I'm just wondering - you are measuring ESR of caps in circuit, caps frequently are in parallel together - it should affect ESR readings somehow, shouldn't it?

Offline nitro2k01

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #12 on: October 07, 2012, 12:16:18 am »
Ah, yes. I have seen those videos, but I don't understand why they don't just "flood" the whole ground plane with solder instead of making those parallel lines.
My guess is that it is because you want a segment of solder to solidify roughly simultaneously over the whole segment when wave soldering. If you have a big solid area of exposed copper, one end might soldify while the other end is still being sprayed with solder.
Whoa! How the hell did Dave know that Bob is my uncle? Amazing!
 

Offline madires

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #13 on: October 07, 2012, 12:18:00 am »
I'm just wondering - you are measuring ESR of caps in circuit, caps frequently are in parallel together - it should affect ESR readings somehow, shouldn't it?

Like resistors in parallel.
 

Online mariush

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #14 on: October 07, 2012, 12:19:59 am »
Yes, that's an important thing that wasn't mentioned at all in the video and it's important.

If capacitors are in parallel, when testing a capacitor the ESR value reported will be much lower, it can fool you into thinking a capacitor is still "good enough" to leave it there, and a few weeks later your monitor is broken again.

I'm otherwise really disappointed.

Dave, considering so many people watch your videos, and you know they're gonna recommend them to others, it's really not a good idea to keep using crap no-name capacitors and excuse yourself saying that's all you have. Also, considering a few capacitors in that area have failed, there's really no excuse for leaving those other capacitors on the board, even though they still measured good, you can never know how long they're going to remain good.  A name brand capacitor is half a dollar, even less, no reason to be cheap with that.

You should be more responsible about this, you're just encouraging people to make poor quality fixes.
 

Offline KD0CAC John

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #15 on: October 07, 2012, 12:22:02 am »
The tool looked to me like a butter knife with the end cut off and I would think a bevel ground on end ?
 

Offline ModemHead

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #16 on: October 07, 2012, 12:24:00 am »
... This tool you use to crack the clips open... how is it called? (seems to be some chisel for medical use?!) ...
It's a "spudger."  Commonly included in laptop and iPad, iPod repair toolkits.  Very cheap on eBay.
« Last Edit: October 07, 2012, 12:27:55 am by ModemHead »
 

Offline madires

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #17 on: October 07, 2012, 12:28:16 am »
I saw your videos on repairing these Monitors and I have done this several times... and I've a little question...
This tool you use to crack the clips open... how is it called? (seems to be some chisel for medical use?!)

AFAIK, it's called spudge tool or spudger.

Quote
I was always fighting with those stupid cases not to ruin the clips and the plastic-case itself. This tool seems to be quite handy (more than a knife, screwdriver, whatever ;) ).

I'm using spatulas (width of 2-3 cm) from the DIY shop. They distribute the torque quite nicely across the width without damaging the case too much.
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #18 on: October 07, 2012, 12:40:49 am »
Ah, yes. I have seen those videos, but I don't understand why they don't just "flood" the whole ground plane with solder instead of making those parallel lines.
My guess is that it is because you want a segment of solder to solidify roughly simultaneously over the whole segment when wave soldering. If you have a big solid area of exposed copper, one end might soldify while the other end is still being sprayed with solder.

Thanks.
 

Offline DL8RI

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #19 on: October 07, 2012, 12:41:25 am »
Hi!

a "Spudger", never heared of... would have never found it... thanks :)

Just ordered two via eBay... will be tested on the next "broken" TFT after my bench is usable again.

73,
Martin
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #20 on: October 07, 2012, 12:56:56 am »
About the spudger, is this one OK?

http://www.ebay.com/itm/Metal-Spudger-Scraper-Knife-for-Ipod-touch-4-Iphone-4-Ipad-2-Repair-Open-Tool-/330744063490?pt=Other_Tablet_eReader_Accessories&hash=item4d01e1e602

Or should I buy some other one?


And about caps, are Fujicon (TN and TM series) any good?
« Last Edit: October 07, 2012, 01:16:52 am by Slobodan »
 

Offline Wytnucls

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #21 on: October 07, 2012, 01:00:59 am »
Wikipedia says it is possible to measure ESR with a square wave generator and oscilloscope. Does anybody know how?
http://en.wikipedia.org/wiki/ESR_meter
« Last Edit: October 07, 2012, 01:02:52 am by Wytnucls »
 

Offline Monkeh

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Offline ModemHead

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #23 on: October 07, 2012, 03:20:46 am »
About the spudger, is this one OK? ...
Looks just like the one I have. It came in a kit with various other plastic implements of destruction. The only one of which I've found useful is the "black stick".  Really.  Just search "black stick spudger" on eBay.
 

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #24 on: October 07, 2012, 03:25:43 am »
Dave, considering so many people watch your videos, and you know they're gonna recommend them to others, it's really not a good idea to keep using crap no-name capacitors and excuse yourself saying that's all you have. Also, considering a few capacitors in that area have failed, there's really no excuse for leaving those other capacitors on the board, even though they still measured good, you can never know how long they're going to remain good.  A name brand capacitor is half a dollar, even less, no reason to be cheap with that.

You should be more responsible about this, you're just encouraging people to make poor quality fixes.

This is a very good point. A lot of people re-cap things with capacitors from RadioShack or Fry's or Maplins. About a month to a year or so later, the device dies - and they wonder why. A lot of it ends up in the trash, and is harder to repair because those caps were "close enough", but not the same.
 

Offline psycho0815

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #25 on: October 07, 2012, 03:37:44 am »
Wikipedia says it is possible to measure ESR with a square wave generator and oscilloscope. Does anybody know how?
http://en.wikipedia.org/wiki/ESR_meter

I never tried it, but here's what i would do:
Put your cap in series with a resistor of a known value, say 100 Ohms. Now connect this to your Signal Generator using a rather high frequency of 100 kHz or so.
Now if you measure the Vpp coming out of the generator and the Vpp over the cap you should be able to calculate the ESR by using simple voltagedivider math.
Problably not very accurate but schould be enough to tell whether the cap is still ok or not.
If you like, check out my blog (german):
http://h-reg.blogspot.de
 

Offline arekm

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #26 on: October 07, 2012, 04:29:08 am »
What about RLC metters that can measure ESR like agilent U1731C (and the rest of U17xx family) ? Are these good enough in measuring of ESR without having to desolder?
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Online kripton2035

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #28 on: October 07, 2012, 04:46:44 am »
also as anyone here saw the interest of esr meters, dont forget to visit my esr repository page
where you can find (almost) all free, DIY, analog, digital and commercial esr meters.

http://kripton2035.free.fr/esr-repository.html

thanks.

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #29 on: October 07, 2012, 04:47:10 am »
What about RLC metters that can measure ESR like agilent U1731C (and the rest of U17xx family) ? Are these good enough in measuring of ESR without having to desolder?

They could be a little better because they can show you capacitance too. If that's significantly off, you know there might be a problem with other caps in parallel.
 

Offline Wytnucls

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #30 on: October 07, 2012, 05:38:49 am »
Wikipedia says it is possible to measure ESR with a square wave generator and oscilloscope. Does anybody know how?
http://en.wikipedia.org/wiki/ESR_meter

I never tried it, but here's what i would do:
Put your cap in series with a resistor of a known value, say 100 Ohms. Now connect this to your Signal Generator using a rather high frequency of 100 kHz or so.
Now if you measure the Vpp coming out of the generator and the Vpp over the cap you should be able to calculate the ESR by using simple voltagedivider math.
Problably not very accurate but schould be enough to tell whether the cap is still ok or not.
Thanks, that seems to work. I get 4.8 Ohms for an old 160V 33uF cap, which is about right according to ESR tables.
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #31 on: October 07, 2012, 06:59:08 am »
Those repairs on monitors with bad caps are very exciting because with little effort you get a tangible result. I still don't understand how people throw these things away. On our local online markets equivalent to ebay you have to pay at least 15 $ to find a broken monitor but in a much worse state. Often they have the LCD panels broken, or in another case the screen is not dark but white! And the guy who tries to repair says the caps are ok, so clearly the problem is not that easy to solve. It is discussed on some forums and they talk about broken fluroescent lamps etc and the way to detect it. They sell here complete power cards for monitors. LCD panels are also sold.
However what is harder to find is an "Alibaba's cave" like the one Dave has. You can see people specialized in gathering junk form streets. Often people sell their old stuff to such people for peanuts so it is harder to see an old monitor or any old electronic equipment in the street.
I shall eventually buy some broken ones if they are relatively cheap in "real stores" not online ones, for training purposes.
So that video was good but may be if there is an occasion, it would be interesting to try more "complicated" repairs.
« Last Edit: October 07, 2012, 08:44:33 am by Rick »
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #32 on: October 07, 2012, 08:08:15 am »
Yes, that's an important thing that wasn't mentioned at all in the video and it's important.

If capacitors are in parallel, when testing a capacitor the ESR value reported will be much lower, it can fool you into thinking a capacitor is still "good enough" to leave it there, and a few weeks later your monitor is broken again.

I'm otherwise really disappointed.

Dave, considering so many people watch your videos, and you know they're gonna recommend them to others, it's really not a good idea to keep using crap no-name capacitors and excuse yourself saying that's all you have. Also, considering a few capacitors in that area have failed, there's really no excuse for leaving those other capacitors on the board, even though they still measured good, you can never know how long they're going to remain good.  A name brand capacitor is half a dollar, even less, no reason to be cheap with that.

You should be more responsible about this, you're just encouraging people to make poor quality fixes.

And quick fixes using the only components you have to hand 99% of of the time always end up being permanent. I agree with your comments - replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #33 on: October 07, 2012, 08:34:21 am »
replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

These comments always amuse me.

Sure, it's free delivery. But you still have to spend £20 to even be allowed to make an order.
 

Online mariush

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #34 on: October 07, 2012, 08:52:50 am »
Only for some countries. For me, it's ~ 5 dollar shipping no matter what, no minimum order at Farnell. RS-Online is also 5 euro shipping, no minimum order.

Digikey.com is a bit more problematic, 20$ or so shipping unless the order is about 200$ or more.

There's other online stores with good reputation.

And I'm in f**ing Romania, where there are none or very few electronics stores with name brands parts. It's cheaper and often faster for me to buy from Farnell than ordering from various local electronics stores. I'm ordering parts on Thursday afternoon and they're at my door on Monday.

Just because a person in Australia may have a harder time procuring quality parts, doesn't mean it's ok to teach a worldwide audience bad "habits".

It's a bad thing when quality is put aside or decreased, just to push something out the door and be done with it...  I don't care about "let's just put any cheap cap from the first electronics store in town I see and upload the clip to youtube, to have my quota of videos for the week" videos.
« Last Edit: October 07, 2012, 08:56:59 am by mariush »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #35 on: October 07, 2012, 09:06:12 am »
Only for some countries. For me, it's ~ 5 dollar shipping no matter what, no minimum order at Farnell.

Good for you.

Quote
RS-Online is also 5 euro shipping, no minimum order.

Their site is an unnavigable maze.

Quote
Just because a person in Australia may have a harder time procuring quality parts, doesn't mean it's ok to teach a worldwide audience bad "habits".

The bad habit here is the naive assumption that parts are easily and cheaply available everywhere and that everyone can afford to pay more for shipping than the parts.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #36 on: October 07, 2012, 09:28:07 am »
replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

These comments always amuse me.

Sure, it's free delivery. But you still have to spend £20 to even be allowed to make an order.

I get free next day UPS delivery with no minimum order. Just set up an account with them :)

Quote
RS-Online is also 5 euro shipping, no minimum order.

Their site is an unnavigable maze.

I don't find it bad at all but you can always order a set of catalogues if you can't use the website. Or just search for the parts you need using part numbers which is the easiest way anyway.
« Last Edit: October 07, 2012, 09:32:06 am by SteveyG »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #37 on: October 07, 2012, 09:31:20 am »
replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

These comments always amuse me.

Sure, it's free delivery. But you still have to spend £20 to even be allowed to make an order.

I get free delivery with no minimum order. Just set up an account with them :)

I do have an account with them. There is a £20 minimum order for card payments.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #38 on: October 07, 2012, 09:33:05 am »
replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

These comments always amuse me.

Sure, it's free delivery. But you still have to spend £20 to even be allowed to make an order.

I get free delivery with no minimum order. Just set up an account with them :)

I do have an account with them. There is a £20 minimum order for card payments.

I mean a credit account and get invoiced at the end of the month.

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #39 on: October 07, 2012, 09:36:27 am »
I mean a credit account and get invoiced at the end of the month.

Because habitually lying is great.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #40 on: October 07, 2012, 09:39:06 am »
Habitually lying?  ???
« Last Edit: October 07, 2012, 09:43:51 am by SteveyG »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #41 on: October 07, 2012, 09:40:03 am »
Habitually lying?  ???

I am not a company. I do not have a company. I do not have company letterhead. Filling out the form claiming I am, I do, and providing something which is not real, is lying. And illegal, just FYI.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #42 on: October 07, 2012, 09:42:49 am »
Who's lying? Call them up, tell them how much you're likely to spend per month and they'll decide whether to give you a credit account or not.

Why do you have such an attitude?

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #43 on: October 07, 2012, 09:45:00 am »
Who's lying? Call them up, tell them how much you're likely to spend per month and they'll decide whether to give you a credit account or not.

*sigh* point totally missed. Congrats.

Quote
Why do you have such an attitude?

Why does everyone else?
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #44 on: October 07, 2012, 09:48:42 am »
*sigh* point totally missed. Congrats.

No point missed. You don't need to be a company for a account there, it's at their discretion. I signed nothing and filled in no paperwork - all done over the phone.

Same Monkeh (attitude) from diynot?

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #45 on: October 07, 2012, 09:50:14 am »
No point missed.

I don't have the money to easily justify a £20 minimum order or spending more on delivery than the parts. What does that suggest about how much I'm likely to spend a month, and as such my eligibility for a trade account?
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #46 on: October 07, 2012, 10:00:46 am »
I don't have the money to easily justify a £20 minimum order or spending more on delivery than the parts.

 :o

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #47 on: October 07, 2012, 10:03:47 am »
I don't have the money to easily justify a £20 minimum order or spending more on delivery than the parts.

 :o

Yes, I'm poor. I do small things. I also have LOTS of other things to spend my limited money on. This is not uncommon.
 

Offline mikeselectricstuff

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #48 on: October 07, 2012, 10:10:15 am »
Habitually lying?  ???

I am not a company. I do not have a company. I do not have company letterhead. Filling out the form claiming I am, I do, and providing something which is not real, is lying. And illegal, just FYI.
What law exactly would you be breaking?
Anyone can be a sole trader 'trading as' a company name.
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Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #49 on: October 07, 2012, 10:10:39 am »
Yes, I'm poor. I do small things. I also have LOTS of other things to spend my limited money on. This is not uncommon.

There must be people on here willing to pool orders?

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #50 on: October 07, 2012, 10:16:11 am »
Yes, I'm poor. I do small things. I also have LOTS of other things to spend my limited money on. This is not uncommon.

There must be people on here willing to pool orders?

I suppose there might be. It makes things awkward if I'm just after a few bits.

What law exactly would you be breaking?
Anyone can be a sole trader 'trading as' a company name.

I'm not a sole trader. I do not trade, I do not keep records as a business, I'm not registered for self-assessment, I am not registered as self-employed..
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #51 on: October 07, 2012, 10:17:55 am »
Habitually lying?  ???

I am not a company. I do not have a company. I do not have company letterhead. Filling out the form claiming I am, I do, and providing something which is not real, is lying. And illegal, just FYI.
What law exactly would you be breaking?
Anyone can be a sole trader 'trading as' a company name.

I think he was implying that he'd be fraudulently saying he was a company when he wasn't in order to get a credit account. So fraud. But you don't have to to get a credit account.

I remember when I first ordered a CPC catalogue, they asked if I wanted to pay for future orders by credit card or pay monthly with a £250 limit per month even though I was 16 at the time. They said they would set the low limit of £250 because of my age. LOL. Still have the letter somewhere where they said I could change to a credit account at any time.

I work for a company now, so never use my personal Farnell account any more but they've still kept it open.
« Last Edit: October 07, 2012, 10:19:49 am by SteveyG »
 

Offline Bored@Work

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #52 on: October 07, 2012, 10:21:21 am »
Quote
Just because a person in Australia may have a harder time procuring quality parts, doesn't mean it's ok to teach a worldwide audience bad "habits".

The bad habit here is the naive assumption that parts are easily and cheaply available everywhere and that everyone can afford to pay more for shipping than the parts.

Waitaminute, yes? In the past Dave told us repeatedly how easy it is in Australia to order parts and get them delivered with free shipping. I am not sure if he talked about RS or Farnell/Element14, or maybe even both. And I am not sure if the free shipping included overnight shipping, but it really didn't sound like a problem at all.

It is maybe time that he orders a nice engineering sample kit with caps from a reputable manufacturer. Maybe he even finds a supplier who wants to sponsor him. Because I also think using these non-name stuff in the videos isn't cutting it.
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Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #53 on: October 07, 2012, 10:27:31 am »
It is maybe time that he orders a nice engineering sample kit with caps from a reputable manufacturer. Maybe he even finds a supplier who wants to sponsor him. Because I also think using these non-name stuff in the videos isn't cutting it.

I find it hard to believe that as a hobbyist he doesn't have basic parts like capacitors to hand from previous projects or from personal component stores.

Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #54 on: October 07, 2012, 10:30:20 am »
Quote
I never tried it, but here's what i would do:
Put your cap in series with a resistor of a known value, say 100 Ohms. Now connect this to your Signal Generator using a rather high frequency of 100 kHz or so.
Now if you measure the Vpp coming out of the generator and the Vpp over the cap you should be able to calculate the ESR by using simple voltagedivider math.
Problably not very accurate but schould be enough to tell whether the cap is still ok or not.
Thanks, that seems to work. I get 4.8 Ohms for an old 160V 33uF cap, which is about right according to ESR tables.

ESR for a cap is most time given for Just one frequency. Most times somewhere between 100Hz and 1KHz. Many ESR meters meaure at 100 or even worse 200KHz.

For 33 uF at 100KHz the reactance is 0.048 ohm. If the ESR is 4.8 ohm a 100KHz that cap is so bad you can not even imagine. That is a D of 99.5 or a loss angle of 89 % ( 0% is an ideal cap, 90% an ideal resitor)

But if you measure at 1 KHz, reactance is 4,8 Ohm ( coincidence or are you just reading the meaurements the wrong way ?) a cap that meaures 4.8 Ohm is a D of 1, also not very good so to say ( 45 degrees loss angle) but if they state ESR for 100Hz Xc is 48.22 Ohm and then a ESR of 4.8 Ohm is a D of 0.099 ( or loss angle of 5.6 degrees) and that is not a bad cap.

So you see, three different frequencys, same ESR totaly different result. Now what was your frequency and what frequency in the datasheet of the cap ? ( or did you use those out of the blue tabels that are printed on ESR meters ?)

However the way with the squarewave works, i tested  it too,  but you must just measure the voltdrop over the ESR alone and that is often so small with regard to the measurement signal that it is hard to do. You realy must zoom in. But it gives an indication if you compare good and bad caps and use the right frequency it can be a quick go no-go test.

A cap has a selfresonant frequency, ESR is minimum there, capacitance and ESL are zeto Ohm. Below that ESR increasing upto almost infinity at 0 Hz and it incresase again after the SRF because the increasing skineffect. Besides that, your meauring an inductor above SRF.

100KHz or 200KHz is only usable if the cap is made for high switching speeds.

ESR is no magic, it is just plain network analysis and you need to know what you measure, to bad many people use  those ( much to expensive) ESR meters without knowing what they measure. And everybodys happy because a real bad cap shows itself ( one you would have seen in a second using your scope to meaure ripple) but a lot of caps that are not bad get replaced too, because at 100KHz almost all caps measure bad, so the result:
This was a good deal, the monitor works again because I found a lot of caps with high ESR.

The truth, you replaced a lot of caos, most however probably had good ESR, but lost capacitance or were leaking DC. But most important your monitor works again

About in circuit meaurement i will not even start ( I make enough enemie allready this way probably  ;) )

I measure ( and examine caps) ESR as a hobby, not while repairing, i designed an ESR meter, build several others, used vna's, bridges ect. Build capacitance meters upto 1 fF. Caps are very interesting.

I find bad caps most times by measuring with a scope for ripple ect. But after that I keep the bad ones and examine them for fun. From the many, many caps I measured ( the right way) only a very few ( like 5 out of 100) really had bad ESR. In smps most caps just lost capacitance, second place is DC leakage, third place ESR.

If a cap gets to hot ( bad design pcb or to hot housing) the water from the electrolyte vaporises and the electrolyte loses its capability to restore the oxide layer. Dielectrium dries out, capacitance decreases and it starts leaking DC, gets even hotter and pops open.

If there is dirt in the cap, or coroded electrodes ESR increases. It is important an ESR meter is not capable to measure Resistance direct ( like only a resistor), unless it measures phase angle because otherway you do not know what is R and what is jX. It is just measuring |Z|. And that is why they measure at high frequency, because most of them only measure |Z| and jX is small at those frequency.
A shorted cap will show a low ESR in that case. A good meter measures ESR upto pF ' s because the principle is the same. But the signal amplitude becomes high, |Z| is high. I need around 10Vtt to measure 10 fF capacitance at 1KHz with my homebuild fF meter. 1 pF is 160MOhm, an extreme good ESR for 1pF at 1KHz is 1600 Ohm. but at 100KHz Xc is just 1.6M so ESR for a real good capacitor is around 15 Ohm.

Now more realistic, most ESR meters stop at 1 uF. Xc is around 1.6 Ohm at 100 KHz, if D is good, say 1% loss angle, D is 0.017 so ESR is just 27 mOhm.  But 1nF is a jX of 1600 Ohm and the same D ( not unusual for 1nF) is 27 Ohm. This is within the range of most meters, so ask your self why they do not measure ESR of a 1nF ? Because they just measure Z, Rest my case  ;)

Damm, when do I learn not to react any more on ESR topics.
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Online mariush

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #55 on: October 07, 2012, 10:39:14 am »
Look the point is...  this video brings nothing new compared to the previous video about fixing monitors.

The only new addition is an ESR meter, which is an old one, no longer available commercially, and there's barely a sentence or two in the video about how esr meters work so there's barely anything educational about using the esr meter. Perfect opportunity to discuss capacitors, esr, why low esr is needed in that circuit etc wasted.

Dave is fixing a monitor so he went to the store and bought a capacitor.. it says LOW ESR on it so it must be true! It also says 105c so whatever, as long as it's 105c it must be fine.

So nice of Dave to look datasheets pointing out the 0.024 ohm impedance for the existing capacitor, but then he goes nowhere, he doesn't explain why this low esr is needed, and certainly makes it look like it's pointless to even bother with it because he goes straight to a no-name capacitor.

Where's the datasheet for that capacitor?  Oh, it's no name, crap, no datasheet available.  It is 105c apparently, but 105c what?  100 hours @ 105c? 1000 hours? Who cares brand name capacitors are 2000 hours @ 105c or even 7000-10000 hours @ 105c when Dave teaches us that any capacitor is good as long as it says 105c on it.

He didn't even bother to use the esr meter to test that no-name capacitor outside the circuit before installing it, at least to compare it to the datasheet of the old capacitor. After installing it, it shows the esr is about 0.04 ohm ... yeah, who cares it's TWICE the value the old capacitor should have been, it's good enough. The guys that made the monitors were probably STUPID when they decided they NEEDED LOW ESR capacitors there, how stupid were they for not saving a few more pennies by buying some more average capacitors.

No mention of ESR measurement being affected by capacitors being in parallel, just a mention that the esr meter can test capacitors in circuit. The youtube comments already show that, several people pointed that out.

Seriously, those Jaycar caps are so bad even the paint on the cover is breaking up in some places, just look at 15:00 in the video, there's holes in the paint... they're THAT good. What is that teaching people fixing their electronics? That they can just buy any crap fake capacitor from eBay or Dealextreme and everything will be fine?

Did this video really had to be rushed, that it wasn't possible to place an order on Farnell or somewhere and spend a couple of dollars on getting the parts before finalizing the video?

There should be a higher standard for these videos, they're not made by some kid on the kitchen table fixing his monitor. As it is now, I believe this video would be ok to post on a secondary eevblog channel, alterzone or whatever, not main channel where lots of people view these videos.

I can understand people like Monkeh who don't have a source of CHEAP quality parts and Dave should cater to this segment by pointing that it is possible to use cheaper components (pointing out potential problems that may come up when you're using these parts).

I just don't agree with him using poor quality, no-name parts, just because of laziness or impatience or unwillingness to wait for a few days for parts to arrive to do a proper video.
 

Online IanB

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #56 on: October 07, 2012, 10:51:11 am »
Look the point is...  this video brings nothing new compared to the previous video about fixing monitors.
It brings entertainment value with some education included. I enjoyed watching it.

Quote
There should be a higher standard for these videos
There "should"? It's provided to you free of charge. Watch it, or don't watch it. It's up to you. But complaining about things provided for free is not justified. Especially when they certainly take some time and effort to produce.

Quote
I just don't agree with him using poor quality, no-name parts, just because of laziness or impatience or unwillingness to wait for a few days for parts to arrive to do a proper video.
So make a better video and post it up on YouTube! I watched this video and previous ones and I learned very clearly that all capacitors are not the same. They have different specifications for ESR, voltage and operating temperature, and capacitors with the same nominal specification can vary widely in performance and durability between brands. Therefore choosing carefully is important. If I learned that then others could learn that too. Dave isn't making videos for 5 year olds, he is making videos for reasonably intelligent adults who can exercise proper judgement and make rational decisions based on information received.
« Last Edit: October 07, 2012, 01:57:04 pm by IanB »
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Offline Bored@Work

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #57 on: October 07, 2012, 11:12:06 am »
What law exactly would you be breaking?
Anyone can be a sole trader 'trading as' a company name.

That depends on the laws in your country. If I would suddenly claim to be a business or sole trader, the tax authorities would hunt me and I would be in trouble for not having registered the business. And if I would register a business the tax authorities would hunt me, too. And if I would use an exception in the local law for liberal professions, which here does include some engineering work, I would again be in close contact with the tax authorities. Because they really don't like the tax exceptions for liberal professions, because there is much abuse going on with them.

I sometimes do consulting as a side job, but I do it via a company in a neighboring country. They employ me for the work, do the legal stuff in their country, get a share of the profit (bastards), and I correctly declare the money I get from them as income earned in a foreign country. A country for which we happen to have a taxation agreement with, so I don't get taxed twice. And all that still does not make it possible that the local Farnell or RS want to deal with me. Because for them I am still a hobbyist, and here they refuse to deal with hobbyists.
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Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #58 on: October 07, 2012, 11:32:21 am »
No point missed.

I don't have the money to easily justify a £20 minimum order or spending more on delivery than the parts. What does that suggest about how much I'm likely to spend a month, and as such my eligibility for a trade account?

Buy caps from eBay.

Would normally be considered unwise if you were getting them from dodgy sources. But I know several sellers who sell genuine capacitors in the UK. If you need a list, ask me or anyone else.

I also live about a mile from Farnell's trade counter, and that only has a £5 minimum order. When I was working in my internship, my company had a business account with Farnell, and could order anything with no minimum order, no shipping charge. I ordered many batches of £2-£3 in caps overnighted by UPS.

If Maplin sold decent caps at their local stores with even a 100 or 200% margin, I would drop Farnell in a heartbeat and often go down there for caps. But they'd rather sell disco lights. Wonder how long that'll work out for them.
« Last Edit: October 07, 2012, 11:35:58 am by tom66 »
 

Offline Pentium100

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #59 on: October 07, 2012, 12:10:16 pm »
I buy caps in my local electronics store and I usually get the good ones. Last time I bought some caps (for a PC power supply) I got ones made by Nichion.
Then again, there are 4 electronics stores in one street, maybe competition keeps them from stocking crap brands (of at least the low ESR caps, I got some Samxon and Aishi normal-ESR caps, but don't really care since they are used in linear power supplies).
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #60 on: October 07, 2012, 12:19:28 pm »
Waitaminute, yes? In the past Dave told us repeatedly how easy it is in Australia to order parts and get them delivered with free shipping. I am not sure if he talked about RS or Farnell/Element14, or maybe even both. And I am not sure if the free shipping included overnight shipping, but it really didn't sound like a problem at all.

They both used to be free overnight delivery by courier.
Now they charge for it again. But you can also go to the trade counter and pick them up in Sydney.

Dave.
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #61 on: October 07, 2012, 12:25:07 pm »
No point missed.

I don't have the money to easily justify a £20 minimum order or spending more on delivery than the parts. What does that suggest about how much I'm likely to spend a month, and as such my eligibility for a trade account?

Buy caps from eBay.

Would normally be considered unwise if you were getting them from dodgy sources. But I know several sellers who sell genuine capacitors in the UK. If you need a list, ask me or anyone else.

I do. I'd definitely appreciate a list of decent sellers, though.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #62 on: October 07, 2012, 12:35:11 pm »
Yes, that's an important thing that wasn't mentioned at all in the video and it's important.
If capacitors are in parallel, when testing a capacitor the ESR value reported will be much lower, it can fool you into thinking a capacitor is still "good enough" to leave it there, and a few weeks later your monitor is broken again.

Yes, I should have mentioned that.
But BTW, if you were paying attention you would have noted that none of the caps I measured were in parallel.

Quote
I'm otherwise really disappointed.
Dave, considering so many people watch your videos, and you know they're gonna recommend them to others, it's really not a good idea to keep using crap no-name capacitors and excuse yourself saying that's all you have.

Why? I pointed out that I was replacing them with unknown caps (not necessarily dodgy, just unknown brand to me).
I am not in the repair business, I had no idea I was going to make another video on this, it just happened. I wasn't going to wasn't going to wait few days and order some brand name caps from Farnell that cost maybe $20. Sue me.

Quote
Also, considering a few capacitors in that area have failed, there's really no excuse for leaving those other capacitors on the board, even though they still measured good, you can never know how long they're going to remain good.  A name brand capacitor is half a dollar, even less, no reason to be cheap with that.

Yes, there was a reason. I didn't have any more caps, and I wanted to finish this impromptu video and head home.
You may not think that's a good enough reason, but I do.
I win, because it's my video  :P

Quote
You should be more responsible about this, you're just encouraging people to make poor quality fixes.

Rubbish. I am telling people to use quality known caps. Just because I don't have them to hand to do an impromptu repair does not mean I am encouraging or endorsing poor quality fixes. This is not kindergarten, people will understand this just fine.
Some people might very well want to do an impromptu fix to just get it working again. Or test that that's the actual problem before deciding to spend more money on quality caps they might not have in stock.
It's a perfectly reasonable video IMO.
I made it clear what I was replacing and the consequences of it.
If you don't like it, and want to correct me, post a follow up video and I will happily link to it.

Dave.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #63 on: October 07, 2012, 12:54:51 pm »
And quick fixes using the only components you have to hand 99% of of the time always end up being permanent.

What's wrong with that if it's your monitor?
If it fails again in short order (unlikely actually) then you know to use better quality ones next time. No big deal.
If it doesn't fail and gives you many years more service, then you did a worthwhile fix.

Quote
I agree with your comments - replacing all of those capacitors with Panasonic FC caps wouldn't have cost more than a few pounds/dollars from Farnell and they'd normally deliver next day for free.

Farnell no longer deliver free, and it's a long drive, not that there was time anyway.
And I was not going to wait to finish the video, that's not my style. It was another simple "is it the cap at fault?" repair video.
So you got what I had.

Dave.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #64 on: October 07, 2012, 01:05:33 pm »
I find it hard to believe that as a hobbyist he doesn't have basic parts like capacitors to hand from previous projects or from personal component stores.

Top quality brand name high value, high temp, low ESR caps designed for SMPS I don't really consider "basic parts" that you'd have in your hobbyist junk bin.
I'm not in the repair business, nor do I roll my own high power SMPS's that often. There is a ton of stuff I don't have in my junk bins.
YMMV
BTW, I do happen to have a couple in the bins, but they were not the right type in these cases.

Dave.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #65 on: October 07, 2012, 01:17:06 pm »
So make a better video and post it up on YouTube!

I'll even post it as a follow-up video!
But of course, the people who complain are never the ones who actually make their own content...  ::)

This video blog has always been in the style of "what's happening in the lab today", or "what I'm thinking about today". Hence you got another quick impromptu repair video, and it was quite valid for me to use whatever brand low ESR cap I had on hand to see if that monitor could be fixed.
I could have talked for another hour on selecting the best capacitor for the job and reading datasheets etc. Was that appropriate to this video? No, it's wasn't.

Quote
I watched this video and previous ones and I learned very clearly that all capacitors are not the same. They have different specifications for ESR, voltage and operating temperature, and that capacitors with the same nominal specification vary widely in performance and durability between brands. Therefore choosing carefully is important. If I learned that then others could learn that too. Dave isn't making videos for 5 year olds, he is making videos for reasonably intelligent adults who can exercise proper judgement and make rational decisions based on information received.

There is a LOT to choosing the capacitor as you say, and it really deserves it's own video, and it would likely be fairly long and detailed.
And even if I did that I'd still get complaints that I missed something, or didn't explain something right, or didn't cater for this situation etc etc.

Dave.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #66 on: October 07, 2012, 01:59:35 pm »
The only new addition is an ESR meter, which is an old one, no longer available commercially,

Wrong.
Perhaps you missed the link I posted to Bob Parkers page that has links to no less than two companies still selling his design ESR meter.
BTW, WTF would you complain about that for anyway?
Would you have also complained if I used an oscilloscope or multimeter you can longer buy?

Quote
and there's barely a sentence or two in the video about how esr meters work so there's barely anything educational about using the esr meter.

Umm, using an ESR meter is exactly what I showed. Zeroing the meter, measuring the cap, and comparing it to the datasheet and/or a typically expected value. What more do you want on using an ESR meter?
(yes, I forgot to mention parallel caps)
Please provide a list of all the things I left out on using an ESR meter, because there must a be lot of them given that there was "barely anything educational" in my video.

Also, perhaps you missed the link I posted to Bob Parkers page that has the full construction and design article for how his ESR meter works, complete with pretty diagrams.

Quote
Perfect opportunity to discuss capacitors, esr, why low esr is needed in that circuit etc wasted.

This video was not entitled "ESR meter and capacitor tutorial". The video had exactly the content is claimed to have.
If I do a future video on the topic I'll link it in.

Dave.
« Last Edit: October 07, 2012, 02:06:11 pm by EEVblog »
 

Offline david77

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #67 on: October 07, 2012, 02:06:49 pm »
+1 Dave.

Some people are lucky enough to live in a country where Farnell happily sell to anyone. Some of us aren't, so getting hold of Panasonic caps is not as easy as it should be.
Personally I couldn't justify a minimum order + postage for a few caps worth maybe 4-5 Euros, so would have to go to the local electronics store and get whatever they have. This of course is supposing there still was a local electronics store - the nearest one is 50km away.

I have some experience running a small local electronics store, so let me tell you why they usually don't stock the top brands of cap suppliers:  You can't easily get hold of small quantities of them, I'm talking about 100s quantities. Panasonic won't even talk to you. Buying from RS or Farnell is not an option, they're just too expensive. You can't buy a cap for 25ct and sell it for 50ct, that simply doesn't work out. As a small business you need to make a decent margin on this stuff. I'm talking about margins well over 500%, that has nothing to do with greed it's simply trying to stay in business.
So in my case I had to settle on Yageo caps, they are easily available from wholesale distributors in reasonable quantities and at a good price.
Of course one could order Panasonic caps in huge quantities at a similar price but that's not economically viable for a small business. Let's say we need about 50 different caps to have a good selection, let's also assume Panasonic have a MOQ of 1000/value. That's 50000 caps, how and in what time does the local dealer shift that? Let's also assume Panasonic charges an average price of 50ct per cap (Wildly optimistic! The large values are realtively expensive.) so we're looking at a bill of 25000 EUR. Just not possible for the small shops, they can't afford stock like that.
 

Offline reagle

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #68 on: October 07, 2012, 02:08:22 pm »
Dave,
the video was fine- a nice mix of being entertaining and providing something new- for example the ESR meter from Bob and where to find it. Anybody with a long list of complaints should just go do something themselves and see that it is better, instead of wasting Dave's time on the threads like this  ;D

I just did an exactly the same thing- friend stopped by with a dead monitor, I searched in my bins, picked something more or less suitable and he went home with a live monitor. I did write down all the caps , so if/when these die, I'll simply order the "proper" ones from DK/Mouser. But that when may be never..
« Last Edit: October 07, 2012, 02:10:08 pm by reagle »
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #69 on: October 07, 2012, 02:12:40 pm »
I just did an exactly the same thing- friend stopped by with a dead monitor, I searched in my bins, picked something more or less suitable and he went home with a live monitor. I did write down all the caps , so if/when these die, I'll simply order the "proper" ones from DK/Mouser. But that when may be never..

*gasp*
You'll be hunted down by the capacitor Nazi's! :o

Dave.
 

Offline reagle

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #70 on: October 07, 2012, 02:18:50 pm »
Well, naturally I had him sign a disclaimer!

Quote

*gasp*
You'll be hunted down by the capacitor Nazi's! :o

Dave.

Offline JoannaK

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #71 on: October 07, 2012, 03:10:06 pm »
also as anyone here saw the interest of esr meters, dont forget to visit my esr repository page
where you can find (almost) all free, DIY, analog, digital and commercial esr meters.

http://kripton2035.free.fr/esr-repository.html

thanks.

For the record .. there are at least two sellers not on your ESR list..

http://clientes.netvisao.pt/greenpal/evb1.htm
http://dx.com/p/100khz-1-7-lcd-auto-ranging-esr-capacitance-meter-black-1-x-6f22-157241?item=4

So for the "Mariush" .. Those are available and on quite many places. And if someone like DX sells a thingie, I'd expect many other chinashops have those too.
 

Offline kek

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #72 on: October 07, 2012, 03:33:46 pm »
Dave - these are great video's, keep em comming.

I picked up this meter off ebay <see attached>. I paid $80 for this as well as a seperate cap meter.

Haven't really put it though it's paces but first impression makes me think it'll do it's job just fine. It's got a picmicro inside with a programming header  if it needs to be repurposed. The pic shows a 100 ohm resistor being measured.

Dave, you should come up with your own version of an ESR meter before your next ESR meter video. I'm sure you'd sell quite a few!

Ken
 

Offline SgtRock

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #73 on: October 07, 2012, 03:35:01 pm »
Greetings EEVBees:

--I much appreciated the views of the data sheets, I was not quite sure if the impedance was the same thing as the ESR, duh, now I am. And a new character has been born the Capacitor Nazi - "No farads for you"

--My friend Dieter says, what with Dave charging more and more for videos where he does not stop, make a Digikey order and resume a week later, Dieter from now on is only going to watch videos by Hauptmann M. Dieter also notes that Dave did not hold up his right hand and recite Ohms Law, which is nearly as grave an offence as the failure to discuss capacitors in parallel.

"He was born ignorant, and has been losing ground ever since."
Fred Allen 1894 1956

Best Regards
Clear Ether
 

Offline Wytnucls

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #74 on: October 07, 2012, 03:41:28 pm »
Quote
I never tried it, but here's what i would do:
Put your cap in series with a resistor of a known value, say 100 Ohms. Now connect this to your Signal Generator using a rather high frequency of 100 kHz or so.
Now if you measure the Vpp coming out of the generator and the Vpp over the cap you should be able to calculate the ESR by using simple voltagedivider math.
Problably not very accurate but schould be enough to tell whether the cap is still ok or not.
Thanks, that seems to work. I get 4.8 Ohms for an old 160V 33uF cap, which is about right according to ESR tables.

ESR for a cap is most time given for Just one frequency. Most times somewhere between 100Hz and 1KHz. Many ESR meters meaure at 100 or even worse 200KHz.

For 33 uF at 100KHz the reactance is 0.048 ohm. If the ESR is 4.8 ohm a 100KHz that cap is so bad you can not even imagine. That is a D of 99.5 or a loss angle of 89 % ( 0% is an ideal cap, 90% an ideal resitor)

But if you measure at 1 KHz, reactance is 4,8 Ohm ( coincidence or are you just reading the meaurements the wrong way ?) a cap that meaures 4.8 Ohm is a D of 1, also not very good so to say ( 45 degrees loss angle) but if they state ESR for 100Hz Xc is 48.22 Ohm and then a ESR of 4.8 Ohm is a D of 0.099 ( or loss angle of 5.6 degrees) and that is not a bad cap.

So you see, three different frequencys, same ESR totaly different result. Now what was your frequency and what frequency in the datasheet of the cap ? ( or did you use those out of the blue tabels that are printed on ESR meters ?)

However the way with the squarewave works, i tested  it too,  but you must just measure the voltdrop over the ESR alone and that is often so small with regard to the measurement signal that it is hard to do. You realy must zoom in. But it gives an indication if you compare good and bad caps and use the right frequency it can be a quick go no-go test.

A cap has a selfresonant frequency, ESR is minimum there, capacitance and ESL are zeto Ohm. Below that ESR increasing upto almost infinity at 0 Hz and it incresase again after the SRF because the increasing skineffect. Besides that, your meauring an inductor above SRF.

100KHz or 200KHz is only usable if the cap is made for high switching speeds.

ESR is no magic, it is just plain network analysis and you need to know what you measure, to bad many people use  those ( much to expensive) ESR meters without knowing what they measure. And everybodys happy because a real bad cap shows itself ( one you would have seen in a second using your scope to meaure ripple) but a lot of caps that are not bad get replaced too, because at 100KHz almost all caps measure bad, so the result:
This was a good deal, the monitor works again because I found a lot of caps with high ESR.

The truth, you replaced a lot of caos, most however probably had good ESR, but lost capacitance or were leaking DC. But most important your monitor works again

About in circuit meaurement i will not even start ( I make enough enemie allready this way probably  ;) )

I measure ( and examine caps) ESR as a hobby, not while repairing, i designed an ESR meter, build several others, used vna's, bridges ect. Build capacitance meters upto 1 fF. Caps are very interesting.

I find bad caps most times by measuring with a scope for ripple ect. But after that I keep the bad ones and examine them for fun. From the many, many caps I measured ( the right way) only a very few ( like 5 out of 100) really had bad ESR. In smps most caps just lost capacitance, second place is DC leakage, third place ESR.

If a cap gets to hot ( bad design pcb or to hot housing) the water from the electrolyte vaporises and the electrolyte loses its capability to restore the oxide layer. Dielectrium dries out, capacitance decreases and it starts leaking DC, gets even hotter and pops open.

If there is dirt in the cap, or coroded electrodes ESR increases. It is important an ESR meter is not capable to measure Resistance direct ( like only a resistor), unless it measures phase angle because otherway you do not know what is R and what is jX. It is just measuring |Z|. And that is why they measure at high frequency, because most of them only measure |Z| and jX is small at those frequency.
A shorted cap will show a low ESR in that case. A good meter measures ESR upto pF ' s because the principle is the same. But the signal amplitude becomes high, |Z| is high. I need around 10Vtt to measure 10 fF capacitance at 1KHz with my homebuild fF meter. 1 pF is 160MOhm, an extreme good ESR for 1pF at 1KHz is 1600 Ohm. but at 100KHz Xc is just 1.6M so ESR for a real good capacitor is around 15 Ohm.

Now more realistic, most ESR meters stop at 1 uF. Xc is around 1.6 Ohm at 100 KHz, if D is good, say 1% loss angle, D is 0.017 so ESR is just 27 mOhm.  But 1nF is a jX of 1600 Ohm and the same D ( not unusual for 1nF) is 27 Ohm. This is within the range of most meters, so ask your self why they do not measure ESR of a 1nF ? Because they just measure Z, Rest my case  ;)

Damm, when do I learn not to react any more on ESR topics.
I used a generic table, as there is no brand name on that cap, which was harvested from a 20 year old top of the line CRT Sony TV.
I fed a 5Vpp square wave at 100kHz (50% duty cycle) through it with a 100 Ohm resistor in series. I also measured an AC current of 47 mA on the circuit. Noticed 240 mVpp on the oscilloscope across the cap, which gives me an ESR of about 5 Ohm for that old cap, applying Ohm's law. Not sure if this is the right procedure, but that cap could be out of tolerance, being so old.
 

Offline SeanB

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #75 on: October 07, 2012, 04:53:09 pm »
RS here does not like the hobby market, but deals with it ( money is money, and business is thin) but does tend to charge a courier fee on low value orders. I normally save up to buy in a batch, and pay by credit card, as this is convenient for me ( although I use this account for work as well, so I have the month end option as well) with a delivery in around a week for most items ( ex UK mostly). Nice is that I can buy hard to get local stuff, and have bought a lot of low ESR caps to fix equipment, as well as motor inverters, VDR's and inrush limiters, along with heatshrink tubing and high temp sleeving.
 

Offline cwalex

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #76 on: October 07, 2012, 05:14:56 pm »
http://australia.rs-online.com/web/generalDisplay.html?id=aboutRS&file=delivery

RS has free next day delivery for all orders placed online in australia. I don't think they have a minimum order, my last order was $7.26. Just some fuses and resistors.

I usually buy my caps on ebay though.

I enjoyed the video. At work I have several monitors that I have recapped. Many of our customers bring their monitors to my shop and ask me to test them. When they turn out to be faulty they usually buy a new one and ask me to dispose of their old one for them, works out nicely. :)
 

Offline David_AVD

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #77 on: October 07, 2012, 06:02:10 pm »
I can't believe some of the negative comments in this thread.  Dave successfully brought the monitor back from the dead with a couple of bucks worth of caps.  Good result.   :)

Some of the armchair experts chiming in here should try producing their own videos before bitching about minor stuff in Dave's videos.   ::)

We use Panasonic low-Z caps to repair some items such as motherboards as they seem to give a better life in demanding applications.  Other times we use relatively generic types (still Low-Z) and have no problem at all.

You have to look at the expected life span of the repaired item too.  How long are you going to keep using a monitor that only has a VGA input for example?

Random comments about solder wick. Try not to touch the unused wick as the oil from your skin contaminates it and decreases it's effectiveness.  Also, sometimes you'll get a better result by adding a little bit of fresh solder to the joint before wicking it.
 

Offline Pentium100

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #78 on: October 07, 2012, 06:57:29 pm »
You have to look at the expected life span of the repaired item too.  How long are you going to keep using a monitor that only has a VGA input for example?
Well, VGA is still present on new cards* and at worst you could get an adapter. My monitor (CRT) only has analog inputs (VGA and BNC), also my KVM switch only has VGA and PS/2 ports (and 8 port KVM switches are expensive).

*I bought a GTX260 one, but it had awful VGA quality - I returned it. My current ATI 6850 has good quality and a GT620 I have displays normally, so that could just be the manufacturer trying to save a couple of cents on the output drivers. My only problem with the 6850 is that it only has one VGA output - I used to be able to connect my monitor directly to my main PC (for better image quality) as well as trough the KVM switch (both VGA outputs set to clone).
 

Offline LEECH666

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #79 on: October 07, 2012, 07:08:50 pm »
[...] Farnell and they'd normally deliver next day for free.

That would be a dream come true, here in Germany. Not only does Farnell in Germany refuse to deliver to private persons (only companies and students), no, they also charge 6 to 8 Euros per delivery. No charge when your order is over 150 Euro. Express delivery is costs extra.

SUCKS! :(
 

Offline Rerouter

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #80 on: October 07, 2012, 07:12:40 pm »
pentium100, the box generally comes with a second dvi-vga adapter ?
 

Offline David_AVD

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #81 on: October 07, 2012, 07:15:27 pm »
... they also charge 6 to 8 Euros per delivery. No charge when your order is over 150 Euro. Express delivery is costs extra.

SUCKS! :(

Just commercial reality I'm afraid.  I wonder how long RS Components will keep (subsidising) the free freight on small orders.

Farnell (Element14) did it for a while, but reverted back to only on orders over AUD $45 early this year.
 

Offline EEVblog

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #82 on: October 07, 2012, 07:58:07 pm »
Just commercial reality I'm afraid.  I wonder how long RS Components will keep (subsidising) the free freight on small orders.
Farnell (Element14) did it for a while, but reverted back to only on orders over AUD $45 early this year.

Farnell started it as a marketing gimmick. RS followed a couple of days later with their own announcement.
If RS still have it (I thought they didn't, but could be wrong), you can expect them to now drop it as well.

Dave.
 

Offline cwalex

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #83 on: October 07, 2012, 08:12:54 pm »
Just commercial reality I'm afraid.  I wonder how long RS Components will keep (subsidising) the free freight on small orders.
Farnell (Element14) did it for a while, but reverted back to only on orders over AUD $45 early this year.

Farnell started it as a marketing gimmick. RS followed a couple of days later with their own announcement.
If RS still have it (I thought they didn't, but could be wrong), you can expect them to now drop it as well.

Dave.

RS definitely still have it. I ordered some things from them a couple of days ago with free delivery.
 

Offline David_AVD

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #84 on: October 07, 2012, 08:13:57 pm »
I fully expected RS to follow suit within a week of Element14 dropping the free freight on all online orders, but they didn't.  That was many months ago now.
 

Offline LEECH666

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #85 on: October 07, 2012, 08:21:06 pm »
Ah well better wording would have been: "Good for you if you can get your goods shipped for free". Instead of "sucks" ;)
 

Offline cwalex

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #86 on: October 07, 2012, 08:26:37 pm »
Ah well better wording would have been: "Good for you if you can get your goods shipped for free". Instead of "sucks" ;)

haha, I'm not bragging. Just wanted to let any of the aussies that might not know about it. :)
 

Offline T4P

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #87 on: October 07, 2012, 08:39:52 pm »
20$ orders get free shipping? Wow good for you .
I have to order like 70$ to get free shipping when the trade counter is only tens of km away from me
Well, VGA is still present on new cards* and at worst you could get an adapter. My monitor (CRT) only has analog inputs (VGA and BNC), also my KVM switch only has VGA and PS/2 ports (and 8 port KVM switches are expensive).

*I bought a GTX260 one, but it had awful VGA quality - I returned it. My current ATI 6850 has good quality and a GT620 I have displays normally, so that could just be the manufacturer trying to save a couple of cents on the output drivers. My only problem with the 6850 is that it only has one VGA output - I used to be able to connect my monitor directly to my main PC (for better image quality) as well as trough the KVM switch (both VGA outputs set to clone).
Generally no more VGA for me if i use it for my main monitor, (well AMD bought over ATI in 2006 and starting from the 6000series no more ATI branding) because i can't drive VGA up to higher resolutions! I never knew 6850 had VGA output versions, was that the free adaptor or what? If i didn't need so much horsepower but more useful outputs i would go for 6450/6570/6670
« Last Edit: October 07, 2012, 08:45:08 pm by T4P »
 


Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #89 on: October 07, 2012, 09:29:27 pm »

I used a generic table, as there is no brand name on that cap, which was harvested from a 20 year old top of the line CRT Sony TV.
I fed a 5Vpp square wave at 100kHz (50% duty cycle) through it with a 100 Ohm resistor in series. I also measured an AC current of 47 mA on the circuit. Noticed 240 mVpp on the oscilloscope across the cap, which gives me an ESR of about 5 Ohm for that old cap, applying Ohm's law. Not sure if this is the right procedure, but that cap could be out of tolerance, being so old.

47 mA will be RMS ? The 240mVpp over the cap is the impedance so ESR and reactance.  47 mA rms will be 94 mApp. So impedance is around 2.5 Ohm. But that is the complex impedance. But besides that you did not measure ESR this way.
You have to meaure the voltdrop over the ESR, not over the cap. It it the part that drops straight down. First the triangle rises, on a fast scope you then see a spike, the ESL, then it drops straight down, the drop over the ESR ( but corrected for the spike) and then the slope goes down under an angle over the Xc. I'm afraid you meaured ESR and Xc together and mixed up rms and Vpp.

The tables are useless for general use because those are made to compensate for the wrong results of the meters.
Use a 1KHz square, ESL is so small in that case it will not matter. Use coax, T-pieces and in line terminators, no probes, this all to avoid ringing. Measure current paek to peak  over a pure resistive dummyload you place between cap and ground. Connect it using a T piece . Use also a T above and below the cap for measuring the voltdrop differential. Voltdrop divided by current is ESR. ( or meaure current differential over a inline resistor above the cap, and measure the cap single ended.

I have a piece on my site about this methode but i made that while ago, corrected it some times when I learned more about this. So some of the math is not excact correct because Later I had not all data needed to correct for some meaurement setups, but the info is for 99 % still OK. I am going to do new meaurements and make a new page with some better compares because i now have the gear to do real excact meaurements as a compare. ( like 0.01% capacitor bridge, vector RF-IV measuement options for both my vnas ect and things like GR reference capacitors with known ESR.

i will post the link here as it is finnished
The old one is at www.pa4tim.nl and use the searche box to look for ESR. You find the page, it is in Dutch and English with a lot of pictures.
« Last Edit: October 07, 2012, 09:32:41 pm by PA4TIM »
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
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Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #90 on: October 07, 2012, 09:34:57 pm »
And about caps, are Fujicon (TN and TM series) any good?

Nobody came across these caps before?
 

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #91 on: October 07, 2012, 09:36:37 pm »
Fujicon? Never heard of them - would avoid myself.
 

Offline KedasProbe

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #92 on: October 07, 2012, 09:53:02 pm »
So what was the capacitance of these bad capacitors with a multimeter, still OK?
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Offline DL8RI

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #93 on: October 07, 2012, 10:18:19 pm »
Hi,

this can be so or so...
Normally if a cap is already physically damaged all of it's values are out of spec.
I had, by coincidence, a really DEAD cap lying around:



That was a 10µF-Cap... 20 Years ago :D

If the Capacitor is not a total loss but somehow "not really 100% well", then the ESR is the first I would look at.
Measuring the ESR is, in respect to switch-mode-devices, more accurate and promising than the capacitance.

73,
Martin
 

Offline tomilepp

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #94 on: October 07, 2012, 10:37:35 pm »
Hi dave, great video again.

I find bad caps most times by measuring with a scope for ripple ect. But after that I keep the bad ones and examine them for fun. From the many, many caps I measured ( the right way) only a very few ( like 5 out of 100) really had bad ESR. In smps most caps just lost capacitance, second place is DC leakage, third place ESR.

I would like to see video about measuruing bad cap with osciloscope.  Is it possible to detect bad one with just looking ripple from scope? How does the waveform differ with bad and good cap?
 

Offline SeanB

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #95 on: October 07, 2012, 10:50:02 pm »
That is easy, if there is ripple more than about 5% of the voltage on the rail directly across the capacitor ( both probe tip and probe ground lead on capacitor terminals) then you can be pretty sure the capacitor is past it's prime. I did that regularly, though in my case it was more to detect that a bridge rectifier diode was either open or short, as the rails were fed from a 3 phase transformer, and loss of a single phase was not noticed until 2 diodes went short, when the supply would burn itself to a stinking molten mass to save the fuses. I would just look for the 6 bumps to be there without a missing one, which then meant I was unsoldering and replacing 6 MC44 ( unobtanium to be sure, last mention in a databook was in the 1972 Ti databook which did not give any specs, only that it was discontinued) diodes with the common and ubiquitous 1N4007 after sanding down the legs to fit the plated through holes in the board. Varnish again with Parylene both sides and screw the lot back together and test again.
 

Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #96 on: October 08, 2012, 12:01:58 am »
most of my repaires are instruments and 95% of the service manuals give you the max ripple and where to measure. But there are some rules of tumb like so much V at so much A with a X uF cap.

DL8Rzi, i have seen over 50 ( lost count, could be much more) electrolityc caps that had lost most of there capacitance ( some just a few nF left) but showed a good ESR.

Repaired a JVC HD/DVD player last year. 34 bad caps, 2 showed high ESR, almost all lost capacitance and 1 or 2 were leaking DC. Few months a go a topfield sat-tuner. 6 bad caps, after repair as usual I examined the caps. ( sometime I also open them) only one showed bad ESR ( on all equipment)  But my own anloge meter showed a wobblimg needle on an other cap that looked good by all other intsruments. But then after some minutes ESR went up, stayed there for a few minutes, then dropped to zero agin and this repeaded unregular. Very strange, no mechnical damage inside so I think some  chemical fault or reaction in the electrolyte.

But the most important reason while meauring ESR as a go/no go is " a waist ot time" is the fact that you, modt times, do not know what the ESR should be, and if you have a datasheet then the frequency of meaurement must be the same as stated in the datasheet. And allmost no one does that, or even knows ESR is frequency dependend.
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
www.schneiderelectronicsrepair.nl  repair of test and calibration equipment
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Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #97 on: October 08, 2012, 12:56:14 am »
Fujicon? Never heard of them - would avoid myself.

OK, thanks. I was asking that because I can only buy CapXon an Fujicon low ESR capacitors in Serbia, and I have to wait for a month for components to be deliverd to me from Farnell...
 

Offline TheWelly888

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #98 on: October 08, 2012, 02:18:28 am »
Thanks for the interesting video, Dave!

This has taught me the practical application of an ESR meter which is what you wanted to demonstrate. I always knew that I can look up the theory of how ESR is measured elsewhere on the internet so ignore the whingers on this thread!

Curiously, I once worked in a PSU factory doing fault-finding, repair and QC and was always able to identify bad electrolytics caps just by looking at the cases and I had never seen an ESR meter let alone used one. One model of PSU used a circuit that exclusively used electrolytic caps so the damn things kept coming back to us and I learned that the quickest fix was to replace every one of those caps! ( after drilling out case rivets, then banging new rivets in! )

That company went under after borrowing too much money to double the size of the factory to supply the dot.com boom in the early 2000s.
You can do anything with the right attitude and a hammer.
 

Online mariush

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #99 on: October 08, 2012, 02:45:51 am »
Fujicon? Never heard of them - would avoid myself.

OK, thanks. I was asking that because I can only buy CapXon an Fujicon low ESR capacitors in Serbia, and I have to wait for a month for components to be deliverd to me from Farnell...

Go on ebay.co.uk  and you'll find lots of UK and EU based sellers that have nichicon, rubycon, united chemicon, panasonic capacitors. Even I sell from time to time capacitors on ebay, when I get some good deals and buy 100-250 capacitors of certain capacities and don't need that many around.
PM me  if you want, I'll be happy to help you out and shouldn't take more than 5-8 days for mail to reach you considering what I send will be considered regular mail, not packages (won't go through customs)
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #100 on: October 08, 2012, 03:22:53 am »
The problem is that Serbia is not "PayPal certified", and I also don't own any of the credit cards, so I have to order the components indirectly, via this firm: http://tagor.mycpanel.rs/tagor.rs/tagor/
And they only order from Farnell.
 

Offline dino

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #101 on: October 08, 2012, 04:15:24 am »
Zdravo Slobodane  ;)

You should get a credit card, for example Visa Virtuon. Electronic stores in Serbia have a poor choice of components, you are better off ordering online.

Your best chance for getting exotic components is Sprint Elektronika from Novi Sad, they order via Farnell every 10 days or so, I got myself some micro usb connectors from Farnell this way :)

this website is well known among the guitar stompbox builders:
http://www.banzaimusic.com/Panasonic-c-1534/
they have some nice panasonic caps
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #102 on: October 08, 2012, 04:25:53 am »
Hvala. (Nece cirilicu da primi majke im ga nabijem  ;D).

Thanks.
« Last Edit: October 08, 2012, 04:27:24 am by Slobodan »
 

Offline Pentium100

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #103 on: October 08, 2012, 06:19:05 am »
Generally no more VGA for me if i use it for my main monitor, (well AMD bought over ATI in 2006 and starting from the 6000series no more ATI branding) because i can't drive VGA up to higher resolutions! I never knew 6850 had VGA output versions, was that the free adaptor or what? If i didn't need so much horsepower but more useful outputs i would go for 6450/6570/6670
The 6850 does not have a separate VGA port, but as a DVI-I port and a free adapter in the box. I use 1920x1200@85Hz, so VGA is good enough for me, the monitor also supports 2304x1440, but then I would have to connect it directly as the KVM switch does not have enough bandwidth. If there are any 24" LCD monitors with equal or higher resolution, they are probably really expensive (or built like crap), so even though my FW900 is old, it it still built properly (because it was expensive when new).
I like to play games, so I have a powerful card :) The GT620 is there for hardware physx.
 

Offline G7PSK

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #104 on: October 08, 2012, 08:18:53 am »
CPC Farnell open accounts for any one in the UK,they had a big tv campaign a couple of years ago to get people to sign up. The problem I have found is to get free delivery you must order over £50-00 otherwise they charge £8-00 delivery even if you buy one resistor that could be posted for a few pence.
Some one asked about using a scope to measure esr I think that W2AEW posted something on this a while back.
 

Offline lowimpedance

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #105 on: October 08, 2012, 12:04:04 pm »
 Just one additional comment about these sorts of repairs (be it monitors, tvs, or whatever), is to check for dry joints as well since more often than not there will be one lurking around those 'HOT' area's.
 I have done my share of monitor etc repairs with the bad caps and have also seen most containing dry joints too. Given what a pain in the rear in getting these items open!!.
The odd multimeter or 2 or 3 or 4...or........can't remember !.
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #106 on: October 08, 2012, 06:42:29 pm »
CPC Farnell open accounts for any one in the UK,they had a big tv campaign a couple of years ago to get people to sign up. The problem I have found is to get free delivery you must order over £50-00 otherwise they charge £8-00 delivery even if you buy one resistor that could be posted for a few pence.
Some one asked about using a scope to measure esr I think that W2AEW posted something on this a while back.

I've not used CPC for many years now, but wow their delivery has gone up! I still have a catalogue somewhere that says £2.50 for orders under £25!

I did manage to blag it once and asked the lady to waive the delivery fee for ordering a single SCART connector :) Never tried it since because for personal orders used to build up an list of parts to order over a few weeks.
« Last Edit: October 08, 2012, 06:45:18 pm by SteveyG »
 

Offline Wytnucls

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #107 on: October 08, 2012, 08:22:32 pm »

47 mA will be RMS ? The 240mVpp over the cap is the impedance so ESR and reactance.  47 mA rms will be 94 mApp. So impedance is around 2.5 Ohm. But that is the complex impedance. But besides that you did not measure ESR this way.
You have to meaure the voltdrop over the ESR, not over the cap. It it the part that drops straight down. First the triangle rises, on a fast scope you then see a spike, the ESL, then it drops straight down, the drop over the ESR ( but corrected for the spike) and then the slope goes down under an angle over the Xc. I'm afraid you meaured ESR and Xc together and mixed up rms and Vpp.

The tables are useless for general use because those are made to compensate for the wrong results of the meters.
Use a 1KHz square, ESL is so small in that case it will not matter. Use coax, T-pieces and in line terminators, no probes, this all to avoid ringing. Measure current paek to peak  over a pure resistive dummyload you place between cap and ground. Connect it using a T piece . Use also a T above and below the cap for measuring the voltdrop differential. Voltdrop divided by current is ESR. ( or meaure current differential over a inline resistor above the cap, and measure the cap single ended.

I have a piece on my site about this methode but i made that while ago, corrected it some times when I learned more about this. So some of the math is not excact correct because Later I had not all data needed to correct for some meaurement setups, but the info is for 99 % still OK. I am going to do new meaurements and make a new page with some better compares because i now have the gear to do real excact meaurements as a compare. ( like 0.01% capacitor bridge, vector RF-IV measuement options for both my vnas ect and things like GR reference capacitors with known ESR.

i will post the link here as it is finnished
The old one is at www.pa4tim.nl and use the searche box to look for ESR. You find the page, it is in Dutch and English with a lot of pictures.
Thanks for all the info; I'll try to measure it all again when I get home. Sounds like an awfully complicated procedure to check a bunch of caps on a regular basis. I think a proper ESR meter is the way to go, if one doesn't mind spending some cash.
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Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #108 on: October 08, 2012, 10:52:48 pm »
That is a nice forward control. I had a 101FC ambulance but with pain in my heart I had to sell it a month ago because of health isues. Still have a 88 series 2a stationwagon ( and a 90 V8 as familycar)
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
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Offline Excavatoree

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #109 on: October 08, 2012, 11:09:59 pm »
On an earlier page, the use of incorrect capacitors was discussed.    When my company threw away about 15-20 monitors, over a few months, I took them and thought I'd try to fix them.

The first three I just whacked in any old cap that fit - I was ignorant and didn't know.  They all worked.  I sold one to a colleague for the cost of the capacitors.   I later learned that I had messed up.   I hadn't considered ripple current. or anything else other than value and size.  These were name brand, capacitors, however.

 I researched and spent some time picking out the capacitors with the highest life and highest ripple current that would fit.   I went a bit crazy, looking at it like an exercise.

I went back in to the monitors with the wrong caps and replaced the two or three that were out of spec.  (didn't meet or exceed the CapXon published spec.  despite the fact that CapXon didn't meet it either.)

I told my colleague that I needed to fix his monitor.  He said he couldn't be bothered to bring it back to me, he'd just run it until it dies.  It's been going for a year now.   I'm interested to see if it lasts as long as it did with the "CrapXon" capacitors.
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #110 on: October 10, 2012, 03:10:13 am »
The capacitors I have ordered have just arrived, and 3300uF 25V Panasonic ones look like they are "No name", they dont look like Panasonic at all (they are just black-white, not black-gold, and there is no manufacturer name).
I have also got some 1000uF 16V and they are Panasonic, and also 1000uF 25V wich are Rubycon.
But on these ones it only says:

3300uF
25V
105oC FR
1025MC

So, did Farnell screwed me?

http://uk.farnell.com/panasonic/eeufr1e332/capacitor-radial-25v-3300uf/dp/1800661
« Last Edit: October 10, 2012, 03:12:48 am by Slobodan »
 

Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #111 on: October 10, 2012, 04:14:24 am »
I am testing several caps on esr on several ways, just finished the squarewave and ESR meter measurements. Measured at 120Hz, 1, 10 and 100KHz. But for the > 1000 uF caps 100KHz gwas useless, their SRF was under 100KHz so they are inductive.

Then I looked up the manul of my peak atlas ESR60. It should measure using 100KHz. But it is very strange, spend an hour measuring with a scope to see the signal. After many one shot, deep memory ect trials every measurement shows just one single pulse. If someone has that peak too, can you hook it up to a scope ?

about the Farnell caps:

One of the caps was a 3300 uF 63V, it was from Farnell but I could not remember what partnumber or brand i ordered that time, It had a M in a square on it, and that is matsushita - panasonic. Its black with grey. But there is no panasonic printed on it, but all other markings are correct for that type. Looked at the bill and indeed I ordered panasonic.

The datasheet from Farnell on your link shows the code ect. Have you looked there ? I think it is original because you ordered a FR series and that is printed on your cap.
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Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #112 on: October 10, 2012, 04:37:19 am »
The other Panasonic cap has "M in a square" symbol but this one doesn't have anything.
I didn't understand what you meant about the codes in the datasheet, it says that the part number is EEUFR1E332( ) but I don't know what 1025MC means.
 

Online mariush

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #113 on: October 10, 2012, 04:40:37 am »
They are proper Panasonic FR, the FR series is updated FM series but with white text on black pvc.

You can tell they're Panasonic by the M in the square with rounded corners, the T  with bent top line and usually they also have a product code with red paint on them, and the distinctive shape of the bottom.
The FR misses some of those depending on the can size. 

PS. The white tape is just my own way of keeping the capacitors organized. I'm a bit anal about it.
« Last Edit: October 10, 2012, 04:44:03 am by mariush »
 

Offline Slobodan

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #114 on: October 10, 2012, 04:51:38 am »
OK then. Thanks.
 

Offline dmather

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #115 on: October 10, 2012, 05:43:37 pm »
Hey I was just wondering, could an LCR meter be used instead of an ESR meter?
 

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #116 on: October 10, 2012, 06:36:43 pm »
If it can measure an R plus  C component - some cannot.

One BK meter using the all-in-one chip for LCR meters sold it as an upgrade for $100! The chip is perfectly capable of doing it, probably just a feature enabled in the main micro eeprom.
 

Offline T4P

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #117 on: October 10, 2012, 07:34:54 pm »
The BK 878A is just a Tonghui LCR meter isn't it?
 

Offline robrenz

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #118 on: October 10, 2012, 10:03:16 pm »
(I initially placed this in the wrong thread and then moved it here. My apologies if you saw it elsewhere)

This thread made me get out my DE-5000 LCR meter and try it on ESR measurements. I was initially disappointed at the low ESR resolution on large value caps but then I wondered if the series resistance mode gives the same readings as ESR in capacitance mode.

To access ESR, D, Q , and theta you have to be in manual series capacitance mode (not auto LCR mode) then you can cycle through each on the secondary display. I can measure a 1000uF cap at 100Hz thru 1kHz but at 10kHz and 100kHz it gives overload which it should. In auto LCR mode it actually shows the inductance of the cap at 100kHz.

The max ESR resolution at 1kHz is 0.01 Ohm and this 1000uF cap reads 0.04 Ohm.  If I switch to reading series resistance it reads .047 Ohm (1mOhm resolution) still at 1kHz. Now in series resistance mode I can switch the frequency to 10kHz and it reads 0.045 Ohm and switch to 100kHz and it reads 0.032 Ohm.

Now a 6000uF cap (reads 7450uF) at 120Hz gives an ESR of 0.0  and I cant go to 1kHz because it will show overload. Switch to series resistance mode and I get 0.075 Ohm at 1kHz, 0.068 Ohm at 10kHz, and 0.065 Ohm at 100kHz.

So it seems the series resistance mode is an effective high resolution ESR reading and allows all frequencies to be used. I could be misguided here so please comment if this is bogus. If this is valid it would think it would apply to all meters using the chipset of the DE-5000.  Anyone with one of the Agilent U1733C LCR's could see if this applies to them also. It has 0.1mOhm resolution in some ranges.

I compared the  DE-5000 to my calibrated LOM-510A on a nominally 50mOhm resistor.  LOM-510A reads 58.76mOhm (max error +/- 35uOhm) and the DE-5000 in series resistance mode at 1kHz reads a very slow bobble between 58-59mOhm and it is on 59 most of the time. I always promote LCR's on the forum for inexpensive accurate low ohms and this is why.


« Last Edit: October 10, 2012, 11:32:30 pm by robrenz »
 

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #119 on: October 10, 2012, 11:54:34 pm »
The BK 878A is just a Tonghui LCR meter isn't it?

Probably. You can get equivalent performance without the BK logo for half the cost.
 

Offline Psi

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #120 on: November 18, 2012, 07:52:52 pm »
Just repaired a Philips LCD today (model 200W) and, for the first time ever, it was the 120uF 400V mains capacitor that was bad.
There was no external sign of failure at all, casing was totally normal.
It was a crap brand though (Capxon)

LCR said 20pF hehe.

So the high voltage main caps do sometimes die.

I could see on the scope that the poor thing was trying to start, but with 20pf of mains filtering it wasn't having much luck :P
« Last Edit: November 18, 2012, 07:56:54 pm by Psi »
Greek letter 'Psi' (not Pounds per Square Inch)
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #121 on: November 20, 2012, 07:13:52 am »
Just repaired a Philips LCD today (model 200W) and, for the first time ever, it was the 120uF 400V mains capacitor that was bad.
There was no external sign of failure at all, casing was totally normal.
It was a crap brand though (Capxon)

LCR said 20pF hehe.

So the high voltage main caps do sometimes die.

I could see on the scope that the poor thing was trying to start, but with 20pf of mains filtering it wasn't having much luck :P

Same problem here with the main capacitor (100 uF 450V, "HERMEI" brand, which look normal) of a Phillips 170s 17" monitor, I think. However it is the ESR value which is equal to 0.38 Ohm. The capacitance was more or less normal 88 uF. If you have measured the capacitance with the Chinese M6013 capacitance meter, it effectively shows 14pF but after 5 sec (!) it displays the real value. I don't have spare parts for these but shall eventually replace them and give it a go. Some others display very slight signs of buldging but have normal capacitance and ESR values... Would you replace them?

2 monitors bought for $17 each for fun (as we don't have a dumpster to dive in here;)). One of them lasts 15 min after power on, then switches off; if you switch it off and on it comes back for a while then shuts down with the led on. The second shuts down 1 sec after power on. 
 

Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #122 on: November 20, 2012, 07:55:07 am »
100 uF and 380 mOhm is not bad for a 100 uF. What states the datasheet and at what frequency ?
And at what frequency does your ESR meter measures ? Or is it just a wild  " lets blame the ESR " guess ;-)
What ripple current did you measure using your scope  ?

I'm almost sure it is just DC leakage instead of bad ESR.

Today I got two bad caps, capacitance should be half of what they new are. Measured with a cheapo meter. They are replaced and that solved it. I could not believe capacitance was that low ( MPX capacitors)

I just measured them, capacitance is perfect, DF is to small to measure. Tommorow I will measure them with DC bias and test leakage current. They are just used to close to their max specs and that killed them.

Fred
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Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #123 on: November 20, 2012, 01:46:18 pm »
100 uF and 380 mOhm is not bad for a 100 uF. What states the datasheet and at what frequency ?
And at what frequency does your ESR meter measures ? Or is it just a wild  " lets blame the ESR " guess ;-)
What ripple current did you measure using your scope  ?

I'm almost sure it is just DC leakage instead of bad ESR.

Today I got two bad caps, capacitance should be half of what they new are. Measured with a cheapo meter. They are replaced and that solved it. I could not believe capacitance was that low ( MPX capacitors)

I just measured them, capacitance is perfect, DF is to small to measure. Tommorow I will measure them with DC bias and test leakage current. They are just used to close to their max specs and that killed them.

Fred

Good guess Fred.
I was working blindly. I have no scope yet.
The datasheet does not mention the ESR value, however my ESR-meter measures the ESR value at 100 kHz. The table on the ESR-meter indicates the maximum value for the ESR is 0.8 Ohm for 100 uF 250 V which is above the value (0.38) I measured. I measured the rms ripple with a multimeter (the much venerated UNI-T UT61E couldn't because the AC is superimposed on the 315V, it started beeping and the display went haywire) it varies between 65 and 300 mV but it is generally around 70-80 mV.
By the way is it safe to use a scope to visualize the voltage on the main capacitor in AC coupling, as the DC reaches 315V (connecting the ground of the scope to the minus terminal of the cap...)? This thing is directly connected to the mains (I guess I need to review switch mode power supplies before doing anything else:) ).

You meant DC leakage through one of the capacitors or the main one? Anyway thanks a lot for your input.

The main cap is an "HT" series.
« Last Edit: November 20, 2012, 01:55:44 pm by Rick »
 

Offline Psi

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #124 on: November 20, 2012, 06:25:31 pm »
Some others display very slight signs of buldging but have normal capacitance and ESR values... Would you replace them?

I normally replace all caps which are showing any sign of buldging.
Sometimes i replace all caps of the same brand as the ones that died.
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Offline PA4TIM

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #125 on: November 20, 2012, 08:10:11 pm »
Ok, i understand your meter then probably measures impedance instead of ESR ( like most do, but its easy to test, a real esr meter has no prolem at all measuring the ESR of a 100 nF cap). They do so because it is the most easy way and Xl is to neglect at 100 KHz so you can measure impedance instead, many datasheets even state impedance at 100 KHz, only the smaller the capacitance, the less you can neglect Xl. And if it does measure Z and also not uses 4 wire technic i would not trust it other then bad/good! like a ESR of 10 Ohm will be bad in 99% of the cases but under 1 of 2 Ohm you have no choise then take the gamble, especially if there is no datasheet or you have no lcr bridge to measure D.

Never disconnect the earth of your scope. The mains potential is then on the chassis and you touch that. Use an isolation transformer to feed the patient ( let the scope allway earthed)  or differential probe. ( suited for this voltage/frequency)
I have scopes that can meaure this even with a 1:1 probe but most of the Chinese toys will not survive that. Look in the manual for max voltage and also for the max value of the probe and the right CAT ratings.

My Agilent multimeter has no problem measuring the AC ripple on 350V, but if yours beeps ect do not try again, if protection is not very well inside it can be over in a flash, i used to have a Voltcraft meter that " flashed" that was the last B-brand meter I ever will buy  (and it was  a top of the line voltcrap scopemeter costing >150 euro)

DC leakage is just DC leakage. An ideal cap has an infinite DC resistance ( Rp) in real life this is very high. If you connect a cap to a DC powersupply, use a current limmiting resistor and connect a sensitive currentmeter ( or measure the voltage dop over the resistor)  in line you will see at first a higher current, hem max that the resistor allows and following the RC time the cap gets loaded. You see the voltage over the cap rising and the current decreasing. After some time ( like a minute or more ) the current must be within the datasheet specs but there are some "rule of tumbs.
Like max 0.001 x V x uF = uA but if a cap leakes over 50-100 uA i replace it.

My standard procedure is measure ripple current  ( not if I must know if caps are right before start up)
then I lift one leg of the cap, measure DC leakage ( and if neccesary reform the cap if the instrument is long not used) then measure capacitance and DF using a HP or GR bridge. From the DF and some calculating i decide for an unknown cap what to do. And then for fun and to see if they are right I take one of my ESR meters and measure ESR.
I have seen caps with perfect capacitance and ESR, not leaking DC at half the working voltage but at the working voltage leaking over 15 mA. If DC leakage is real bad, ESR will be super good.
Caps that have perfect ESR, do not leak DC but lost most of theire capacitance ( most time electrode ripture, a chemical problem.
If it is lost capacitance because total loss of oxide layer then there often is DC leakage.

Upto now I have found lots of caps leaking DC, most of the rest lost capacitance and i think about 10 with a high ESR and 4 of those were in an old HP bridge, the others in consumer electronics, but 99% of my repaires are instruments. I know bad ESR is a bigger problem in consumer electronics, but not so bad as many people think, our ESR meter just let us think it is a big problem. And because this way we replace many more as nessecary we most times also replace the DC leaking or lack of capacitance caps so the result is a working monitor and we are happy ;-)

i know, i'm wrong because you all have good ESR meters and I talk bullshit, but for everyone who does not agree, i do not care,   ;) only if you measure DC leakage, capacitance with a real good meter ( and ESR not in situ and at he right frequency, mine is adjustable from 10-100KHz, so I can measure at the frequency the datasheet gives and under 10KHz I use a bridge) and then if you still disagree tell me  %-B

« Last Edit: November 20, 2012, 08:13:26 pm by PA4TIM »
www.pa4tim.nl my collection measurement gear and experiments Also lots of info about network analyse
www.schneiderelectronicsrepair.nl  repair of test and calibration equipment
https://www.youtube.com/user/pa4tim my youtube channel
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #126 on: November 20, 2012, 10:50:08 pm »
It's going to be an expensive repair if any:)
Let me open the second monitor to see if there is any visual sign there. I think both have the same problem one having a bigger issue than the other.
Some people must have tried to repair it because the frame of the monitor was already opened before. There was something moving inside and when I opened I realized it was a plastic retaining clip. They broke it when opening. The problem is there may not buldging at all, it may be my impression, because if there is any sign it is very very slight. I cannot show the pic right now unfortunately.
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #127 on: November 21, 2012, 10:59:26 am »
I desoldered the main cap and measured its leakage current at 32.4 V, the maximum available here. I measure 5 uA. It's value is 95 uF very close to what it should be, the ESR is low. I think none of the caps is buldging. I checked them against new ones, they look similar. I forgot to do the "flash lamp test" to see if the lights are bad, the fluorescent lamps I mean. All the fuses are ok. The diodes too. Not an easy repair this one, right? I wish I had bad fuses, bad caps etc:) So the expected fun turned into nightmare, especially that I ripped off accidentally one of the connectors for the fluorescent lights. I need to improvise connectors now.

« Last Edit: November 21, 2012, 12:02:08 pm by Rick »
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #128 on: November 21, 2012, 12:02:32 pm »
Sorry, it was easy actually but I did not think of it rightaway. The fluorescent lights are dead (for at least one of them). Thank you for the advices anyway. They may help in another repair. They are always useful.
 

Offline Rick

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #129 on: November 22, 2012, 06:37:39 am »
I have found this on the web:
http://elec-stuff.blogspot.com/2011/02/philips-170s-repair.html

But I have been unable to identify the backlight inverter controller BIT3193G they are talking about, on the power board...

On the other hand, the seller told me it is the inverter circuit which has a problem. He suggested to buy a led driver board therefore I should also replace the fluorescent lamps by led lamps. The board itself costs less than $10. I don't know about the price of the leds though.

Note: on my board there is a OZ9938GN

+

A pair of led boards (for a 17" monitor) cost $19!
10+19+17=$46 I believe it was possible to buy a working second hand monitor for that price! And it is not yet guaranteed that it will work.
« Last Edit: November 23, 2012, 04:46:44 am by Rick »
 


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