Equivalent, or better, replacement for CapXon 10uF, 50Vdc cap

It is amazing to see how much you agonize over a part that costs less than

15 cents at retail. What is your criterion for "better"? What is the func tion of these capacitors (coupling, bypass, resonator, etc)? Do you need a hermetically sealed or a vented package? What is the actuasl dc working v oltage? How large is the ac component? Since it is in a Vizio, I would gu ess the most important parameter is "chaep". In the absence of real knowle dge, I would guess it is a bypoass of some sort, and I would use any cheap electolytic in the 10-47uF range, as long as I could make it fit; I would b uy ones with at least a 50 WVDC rating, but you might be able to get away w ith less if you really understood your circuit (thereby saving 2-5 cents). For long term reliability, you might choose tantalum capacitors in metal c ans with glass seals, but they have functional disadvantages in some circui ts (bseides being larger and more expensive).

if this reading is only showing at 100khz and not at 1khz, what do you think you're going to improve?

These things do have inductance... if it really bothers you that bad then put a few in parallel of smaller values. Also, you can tie a non inductive type of a low value across it to help at the higher frequencies.

Jamie

Tom, thanks for the EXACT URL that looks like it'll work!

At one PCB location, the cap is vertically mounted next to another cap, so could get tight. The other place, it's all by itself bent down with the body parallel to the PCB surface. so very likely easily made to fit in both places.

The ambient in our home is higher than 'office' temperature, [Arizona summer easily 80, often nearer to 90F] wonder if should go for the 125C caps? thoughts? Whether to increase operating voltage or increase temp range? I know, that's only 10+C more than office, but still every 10C drops the MTBF by half. Let's see lasted 18 months, in office temp would have gone 3 years, sounds about right.

Tom found a suitable replacement, cost $2 each

Might want to rethink your guesses. These caps are in the SMPS section so probably [I'm not privvy to the details of their design] gets hit with heat from the heat sinks, AND likely high ripple current, AND operates at high frequency. [I assume at/above 100kHz, because that fundamental tone in your SMPS doesn't do a lot of damage to any attempts to meet your conducted RFI/EMI compliance requirements.

Why dont you restore the old capacitors? The high ESR is probably due to d ried-out electrolyte. Get a hypodermic needle and carefully (so you don't short out the foils) inject some water (distilled will work better than tap ). You might also need to re-form the dielectric. Total out-of-pocket cos t: zero!

Let's see, the Zc at 1kHz for a 10uF cap is 16j ohms. The inductance better not be more than that or the Resr be more than that.

However, at 100kHz the reactance of a 10uF cap is around 160mj ohms. That could make measuring the expected 30m ohms of Resr difficult without an LCR meter type instrument.

For inductance assuming a very small 30mj of inductance implies 50nH of inductance. That's about 2 inches of free wire. and seems a bit high for even a 10uF cap!

Plus, this cap is in the SMPS section where most of these type caps are prone to fail. so 100kHz is closer to the expected operating frequency range.

Oh, I'm tempted! Even as a simple challenge! I have several bottles of distilled water used for cleaning house windows, bathroom mirrors, and the Stainless Steel appliances that some idiot thought looked good in a kitchen! You're talking to a guy that spent three hours to fix an $8 hair drier, so I am tempted to try. Or, you already know about my penchant for cheap and are simply teasing the old guy?

How about 'soaking' in distilled water for extended period of time? Think the H2O will wick itself up in there?

Having only milli-ohms of ESR, the internal temp should be close to ambient. You will be surprised how small these are.

Have fun and good luck.

Why dont you restore the old capacitors? The high ESR is probably due to dried-out electrolyte. Get a hypodermic needle and carefully (so you don't short out the foils) inject some water (distilled will work better than tap). You might also need to re-form the dielectric. Total out-of-pocket cost: zero!

Only if you value your time at 0. That and how many times can you rework the irreplaceable (at reasonable cost) PC board.

In my experience it is normal for such a small capacitor to read a few ohms ESR. Are you sure these capacitors are giving you trouble?

not sure, assumed. It's just the high Resr stood out compared to all the other caps around there. Most appeared to be in the 10 milliohm ranges.

From memory, I expected 0.03 to 0.3 ohms, with 0.3 ohms being on the high side for Resr, so when I found 1.7+ ohms, thought that was the problem. And that Resr drops quite low by adding a bit of heat.

Then just replace them.

I like knowing the exact reason something isn't working. But that isn't always possible. Sometimes you have to go through a "try anything" shotgunning. You won't get much intellectual satisfaction -- but at least the unit will be fixed.

The problem is, "internet knowledge". SO instead of being about teaching, it's about solutions. Take a look at that bad caps forum. Set up to deal with real problems based on a bad batch of electrolytic capacitors, and the ongoing issue of electrolytic capacitors going bad due to too high heat and high frequency ripple, suddenly that bit of folk knowledge is extended to all capacitors, rather than understanding why some might go bad, and others may never go bad.

Anyone can pull the electrolytics off a switching supply and in many cases have success in getting the item back working. That gives more people the ability to get their LCD monitor going again, and the same solid state advances that make it doable have also made the boards so much easier to access.

But if that doesn't work, they are stuck. They don't know electronics, but they do know that key bit of knowledge "capacitors can go bad". So they wonder if it's the filter capacitor on the AC side of the supply, and anything can go bad, but since it's running at 60Hz it's not under the same strain as the filters on the output of the switching supply. And it goes on, people wondering if they should change ceramic capacitors. They "know" the lingo, so they'll worry about counterfeit capacitors and buy only the "right" brands, but unless the problem is what's mapped out, they are lost.

Michael

** That is a quite normal reading.

Tiny, low value electros have ESRs in that range.

.... Phil

You got on my case over a post about that. THAT is exactly what I meant abo ut the ESR should be less than a certain amount compared to Xc. Something l ike that.

However that does vary circuit to circuit of course. Some are very tolerant , others go apeshit at say five ohms for a 10 uF. Usually however, the engi neer uses a higher value cap to take care of that. It usually takes care of ripple current problems as well.

But on topic, what this means is that this guy's problem is not solved.

We don't even know //what// his problem is. He never said.

Why was he testing the caps? Is there something wrong with the unit? Or was he just curious?

There was a previous thread about how my Vizio TV would run and run and run. But turn it off and it was difficult to turn back on, took several tries. So, we left it run all the time. ...until a power outage. That took a long time to get the TV back on again. ...until the next power outage, so bought a new TV and stored the Vizio, and posted question here as to where to look, the consensus was "look at those cheap dried out electrolytics in the SMPS section, because their Resr is lowered when caps are hot, so that's why the TV worked" [to paraphrase]

You may also recall a thread discussing the findings of using the soundcard to determine both C and Resr as a function of Frequency. Time passed, and then encouraged by Bob Masta releasing his new version of Daqarta which included an LCR meter, I went back to the lab and pulled out the Vizio. Suddenly, duh! in a fit of expediency, I used the lab's Function Generator and a DVM capable of 100kHz Vac. Set the voltage low enough I went on a 'check the caps' spree. Just went checking through the SMPS section, only spot checking other sections. That's when I found these suspect caps, including caps used 'identically' elsewhere that also had excessively large Resr. Note the caps in the SMPS section had high Resr while the exact same type cap used in generic bypass elsewhere had expected Resr.

Now, I know these caps should be replaced, but as I went to replace them, I could not easily find the 'original' capabilities and did not trust my suitable replacements [merely stating uF and Vdc]. Thus, I posted this new thread asking for "Equivalent, or better, replacement for CapXon 10uF,

50Vdc cap" You understand, I didn't even know these caps' tolerance!

And Tom found a Nichicon at Mouser for $2 that is 10uF, 80Vdc, and Resr of

40 milliohms! and is exactly 5mm by 12mm, so will fit. And Nichicon also makes a tighter tolerance one that can take 100Vdc, in the same size!

All this sequence of events may appear to the casual observer as, "bouncing off the walls", but to me the path has been a 'linear' one. Albeit slow.

Absolutely. But since it took several years to dry out the electrolyte und er positive pressure, at 1 atm it will take at least as long (and probably a lot longer) to diffure it in from the outside; you could speed it up by u sing your wife's pressure cooker.