Zero ESR Electrolytic - Page 1
Forum section: electronics / projects

author: SgtRock
author_rank: Unknown
timestamp: April 04, 2014, 02:31:38 am
content: Greeting EEVBees:We rescued an LG LW65114 6500 BTU air conditioner from the curb. I determined that the digital control unit was highly intermittent and and most times very dim, even with compressor and motor disconnected. Finally I found an electrolytic 10uF 50V cap that was only 6.4uF and showed a zero ESR. I pulled another one just like it and it read 9.6uF and ESR of 3.4 Ohms, well within spec.Just to be sure I intend to replace all 6 no name caps on the control board. But I was wondering if anyone else has found caps with zero ESR. Any comments would be welcome."I'll have the alfalfa sandwich and the smashed yeast"Allan Stewart Konigsberg - Woody Allen1935 -Best RegardsClear Ether

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 04, 2014, 03:09:55 am
content: Shorted? Or "OL" ESR?Depends on how the meter reads it. A meter typically tests with one very narrow condition (probably as low a voltage, current and frequency as is practicable?), which is hardly representative of the "capacitor-ness" of a given component over a wide range of those values.I don't have a "meter" myself (if I need to test something, I'll just put the signal generator on it), so I don't know about occurrence.Tim

author: Richard Head
author_rank: Frequent Contributor
timestamp: April 04, 2014, 07:03:18 am
content: If the ESR had dropped to zero then it has improved! Where can I get these caps please?

author: dannyf
author_rank: Super Contributor
timestamp: April 04, 2014, 11:30:35 am
content: Depending on how your meter measures ESR, 0 ESR typically means trouble: it could be that the meter is faulty; it could be that the capacitor is shorted out; or it has extremely low / truly zero ESR (which is bad as well).

author: TheRuler8510
author_rank: Regular Contributor
timestamp: April 04, 2014, 12:28:45 pm
content: Quote from: SgtRock on April 04, 2014, 02:31:38 amI think an easy way to think about it is 6.4uf is out-of-spec and is a more important indicator in this case. Different test frequencies can also reveal helpful info.I have replaced caps that showed in-spec ESR and in-spec capacitance but improved the system after replacement. Anybody else ever seen that? The only thing I figure that can explain that is that there can be bad non-linear effects that the ESR meter won't tell you about. Anyhow, feel lucky you found the problem.The ESR test is not always an ultimate test--but just another indicator.

author: Richard Head
author_rank: Frequent Contributor
timestamp: April 04, 2014, 12:30:25 pm
content: I wish I could find a 0 Ohm ESR electrolytic cap. You could put any ripple current through it with no heat generation!

author: SgtRock
author_rank: Unknown
timestamp: April 19, 2014, 06:58:11 am
content: Dear NHM:--I am glad you mentioned the filter cap. I decided to replace it with a better one, and next time I will try to get a higher voltage. The swollen Nichicon that I put in backwards still had a passing ESR of 0.13, but obviously on its way out. It made a loud crack after being on about 6 seconds. The original L.H. Nova 15uF 450 filter cap has a passing ESR of 1.6 but was beginning to degrade. The Nichicon 15uf 450 I replaced it with was too tall so I just leaned it over a bit. See pictures below. I am pretty sure the fan and compressor are good so if I can fix the digital control, I have got a 1 year old AC for chicken feed."Get ready Little Lady Hell is coming to breakfast"Chief Dan George 1899 - 1981Best RegardsClear Ether

author: NiHaoMike
author_rank: Super Contributor
timestamp: April 20, 2014, 02:35:56 am
content: Check the run caps and (if there is one) the compressor start cap. When those start to fail, you'll end up with an A/C with intermittent faults and the efficiency would be much lower than expected. On the control board, I recommend upsizing the power supply caps.

author: wraper
author_rank: Unknown
timestamp: April 20, 2014, 11:47:21 am
content: What device did you use to measure ESR? Some meters no not use sine wave to measure ESR and capacitance. For example, they may feed square and measure charging time. Then they calculate capacitance/ESR by some formula. Downside is that in many cases calculations are completely wrong, lets say, because of the current leakage in the capacitor. Therefore results can be weird. Many good ESR meters put 100 kHz sine on the capacitor and measure voltage amplitude. You can always trust the results but they don't measure other parameters. Therefore a proper LCR meter is much better as you can always trust to the readings and know all important parameters.

author: dannyf
author_rank: Super Contributor
timestamp: April 20, 2014, 03:37:38 pm
content: QuoteMany cases non-calculations are completely wrong too.QuoteMost meters, including the "proper ones" you described below, will fail if the capacitor is leaky.QuoteMany of today's LCR meters (network / impedance analyzers more precisely) are calculations driven.Each approach has its own limitations. Just because they have flaws doesn't mean they cannot be used.

author: SgtRock
author_rank: Unknown
timestamp: April 21, 2014, 12:20:10 am
content: Greeting EEVBees:--I am using the AnaTek Blue ESR Meter by Bob Parker. It gives unambiguous readings, and has save its cost (for the kit) many times over. This LG LW65114 6500 BTU air conditioner appears to be less than a year old, and I assume that the failure of the original small cap was caused by a line transient, and not age. Nonetheless I replaced all of the capacitors, except for the large dual motor run cap (see picture below) for the fan and compressor. It looks and tests just fine.--The power supply filter cap was a 15uF 450 V, which showed some degradation (although it passed the ESR test), and was replaced by Nichicon of the same specs. I did not know how much to increase the capacitance by, as recommended by NHM. Recommendations?--In any case the AC is now running great guns and has 100% functionality including the remote control. Now it just needs a good cleaning, as the original owner left the drain hole plugged and the bottom of the case is a bit gummy."If Mr. Einstein doesn't like the natural laws of the universe, let him go back to where he came from."Robert Benchley 1889 - 1945Best RegardsClear Ether

author: wraper
author_rank: Unknown
timestamp: April 21, 2014, 12:51:32 am
content: Quote from: dannyf on April 20, 2014, 03:37:38 pmI didn't say that they cannot be used. But flaws should be taken into account. Difference is that with proper LCR meter you will notice by other parameters that capacitor is bad. Some simple combined capacitance/ESR meters will just tell you completely wrong figures too often. Therefore you cannot completely rely on them. I mostly use my DIY ESR meter for repairs BTW.

author: wraper
author_rank: Unknown
timestamp: April 21, 2014, 01:06:07 am
content: I briefly looked the schematic of the blue meter. Zero ESR was definitely just glitch of the meter itself.

author: dannyf
author_rank: Super Contributor
timestamp: April 21, 2014, 01:21:14 am
content: QuoteTrue. But you cannot completely rely on those "proper" LCR meters as well.Actually, you cannot completely rely on anything, at least until we invent perfect instruments and perfect human beings to use / interpret those perfect instruments.

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2014, 05:28:03 am
content: The dual cap is likely good for another 2 summers before it will need checking again. When capacitance on the motor or fan side has dropped 20% from nominal then replace it. It drops because of self healing of the internal foils. To clean the coils use a neutral coil cleaner, you can get a citrus coil cleaner that works very well from most AC suppliers. Spray on coils and rinse off with a hose, then leave to dry.The drain being still closed is to allow the condensor fan to pick up the water and use it to cool the coil, though this also has the side effect of rotting the coil from the inside out, so it fails after a while, but still looks fine on the outside, with the inner side being a mass of corrosion and powder. You get a coil coating spray to reduce this, spray from inside the coil (open top cover and spray) then leave to dry.

author: SgtRock
author_rank: Unknown
timestamp: April 21, 2014, 06:26:07 am
content: Dear SeanB:--Thanks for the knowledgeable advice. I shall follow it. My brother spoke to the people who discarded this AC, and they confirmed it is less than a year old. Sheesh, what a mess, see picture below. I will vacuum, the blow out with an air compressor, and then clean is with a good cleaner and spray the coils with a protectant as you suggest. Would it be worthwhile to put some rustoleum on the inside of the corroded case bottom.--I really enjoy your work on The Game of Thrones."We are constantly being surprised that people did things well before we were born."Robert Benchley 1889 - 1945Best RegardsClear Ether

author: wraper
author_rank: Unknown
timestamp: April 21, 2014, 07:44:51 am
content: Quote from: dannyf on April 21, 2014, 01:21:14 amWell, by "completely" I meant usual expectation from a very good gear you can trust. Those ESR meters often are much below that, therefore one should be skeptical about measurement results. Manufacturers specify ESR at 100khz for LOW ESR capacitors. Therefore ESR measured by other methods at least cannot be considered accurate (because measured in unknown conditions) and cannot be directly compared to the datasheet what people do a lot. Everyone should have their own brain to interpret results anyway and think if something seems strange.

author: SeanB
author_rank: Super Contributor
timestamp: April 21, 2014, 09:06:36 am
content: Typical inside. Yes, wash the coil with a hose, not a high pressure cleaner ( it destroys it) and of course paint the inside with whatever rust protection paint you want. You can see where it has been spraying the condensate water around, and how it already has corroded the coils. Bet the outside still looks perfect and golden coloured.

author: dannyf
author_rank: Super Contributor
timestamp: April 21, 2014, 11:19:04 am
content: The key to understand this all is to recognize that esr measurements, like any other measurements, are not absolute - they are indicative, based on simplistic and flawed assumptions of the dut. As such, there is a valid range of values given the test approach and applications. No point in hanging to one particular approach - however "advanced", it can be more wrong for a given application.- Manufacturers specify ESR at 100khz for LOW ESR capacitors. Therefore ESR measured by other methods at least cannot be considered accurate (because measured in unknown conditions) and cannot be directly compared to the datasheet what people do a lot.-the est measured at a different frequency may not be comparable directly with the manufacturers spec, but it can be accurate, valid, or in some cases, more desirable or useful than the spec : what if you intend to use the cap in a 10khz environment? The 100khz spec wouldn't be as useful there.again, think of all esr measurements as being indicative.

author: The Electrician
author_rank: Frequent Contributor
timestamp: April 21, 2014, 07:12:34 pm
content: Quote from: dannyf on April 21, 2014, 11:19:04 amWhat simplistic and flawed assumptions are you referring to?