Author Topic: EEVblog #365 - ESR Meter Bad Cap Monitor Repair  (Read 45241 times)

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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.
 

Online 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
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 #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
https://www.youtube.com/user/pa4tim my youtube channel
 

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)
 


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