Author Topic: EEVblog #365 - ESR Meter Bad Cap Monitor Repair  (Read 46085 times)

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Offline psycho0815

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #25 on: October 06, 2012, 04:37:44 pm »
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.
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Offline arekm

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #26 on: October 06, 2012, 05:29:08 pm »
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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Offline kripton2035

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #28 on: October 06, 2012, 05:46:44 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.

Offline tom66

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #29 on: October 06, 2012, 05:47:10 pm »
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 06, 2012, 06:38:49 pm »
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 06, 2012, 07:59:08 pm »
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 06, 2012, 09:44:33 pm by Rick »
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #32 on: October 06, 2012, 09:08:15 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.

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 06, 2012, 09:34:21 pm »
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 06, 2012, 09:52:50 pm »
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 06, 2012, 09:56:59 pm by mariush »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #35 on: October 06, 2012, 10:06:12 pm »
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 06, 2012, 10:28:07 pm »
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 06, 2012, 10:32:06 pm by SteveyG »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #37 on: October 06, 2012, 10:31:20 pm »
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 06, 2012, 10:33:05 pm »
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 06, 2012, 10:36:27 pm »
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 06, 2012, 10:39:06 pm »
Habitually lying?  ???
« Last Edit: October 06, 2012, 10:43:51 pm by SteveyG »
 

Offline Monkeh

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #41 on: October 06, 2012, 10:40:03 pm »
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 06, 2012, 10:42:49 pm »
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 06, 2012, 10:45:00 pm »
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 06, 2012, 10:48:42 pm »
*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 06, 2012, 10:50:14 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?
 

Offline SteveyG

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #46 on: October 06, 2012, 11:00:46 pm »
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 06, 2012, 11:03:47 pm »
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.
 

Online mikeselectricstuff

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Re: EEVblog #365 - ESR Meter Bad Cap Monitor Repair
« Reply #48 on: October 06, 2012, 11:10:15 pm »
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 06, 2012, 11:10:39 pm »
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?


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