Is there any downside to using capacitors with higher rated voltage? - Page 1
Forum section: electronics / beginners

author: silviasol
author_rank: Regular Contributor
timestamp: May 23, 2017, 04:49:12 pm
content: I am fixing sega game gear systems which have capacitors from the early 90's which I guess had to use poor quality capacitors with fish oil(unsoldering the caps actually smell's like fish, lol) to comply with the overseas transport laws back then. The kit I bought on ebay has higher voltage capacitors, some short research I did shows that only the ohm rating matters so long as the voltage of the cap you are replacing is below the new cap. Just wondering if there is any benefit if I bought my own capacitors with matching voltage ratings. It is battery powered if that makes a difference with the voltages fluctuating as they drain.

author: james_s
author_rank: Super Contributor
timestamp: May 23, 2017, 04:57:41 pm
content: Generally speaking there is no problem using capacitors of a higher voltage rating. They tend to be physically larger and if you go way too high the ESR tends to be higher but in your case it is no problem at all.

author: that_guy
author_rank: Contributor
timestamp: May 23, 2017, 05:05:37 pm
content: Too little ESR can be a problem in subcircuits that require some for stability. Eg the output cap on a voltage regulator.

author: mariush
author_rank: Super Contributor
timestamp: May 23, 2017, 05:11:36 pm
content: Some voltage regulators (and some other ICs) require a minimum ESR value on the output capacitors, the 1117 linear regulators are a typical example... they recommend using capacitors with at least 0.1 ohm ESR for that series of regulators.If you use capacitors rated for higher voltage, these are often in bigger can sizes, which means lower ESR, so in some situations the ESR may drop below some safe threshold and then the linear regulator may become unstable.

author: Seekonk
author_rank: Super Contributor
timestamp: May 23, 2017, 06:03:58 pm
content: Higher voltage capacitors will generally give longer life. If getting old stock capacitors on ebay you better get higher voltage caps in order for them to survive without going through the process of reforming. Stubby capacitors of the same value as tall ones usually have a higher ESR.

author: retiredcaps
author_rank: Super Contributor
timestamp: May 23, 2017, 06:11:09 pm
content: Quote from: silviasol on May 23, 2017, 04:49:12 pm99% of the capacitors sold on ebay are pure crap or counterfeit. Yes, there are good sellers on ebay who sell the real item, but it is like finding a needle in the haystack.Post a link to your ebay auction so we can see what you bought.Since you live in the USA, for future orders, digikey and mouser are two good reputable distributors to get quality Japanese caps like Nichicon, United Chemicon, Rubyon and/or Panasonic.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 23, 2017, 06:36:40 pm
content: Remember that the situation is different depending on whether you are talking about electrolytic (polarized) capacitors or "conventional" (non-polar) capacitors. It is quite common to see high (100V) ratings on very small (pF & nF) capacitors because it would actually be more difficult/costly to make lower-voltage rated capacitors (because of small size) and the caps are small enough that nobody wants to bother with using lower-voltage caps. Plus there is no electrical advantage to using lower voltage caps.OTOH, electrolytic capacitors depend on some good percentage of their voltage rating to develop the capacitance rating. In addition to all the discussion of ESR, there is also the matter that using an electrolytic capacitor with a 2-3-4x voltage rating above the actual circuit working voltage may be expected to not develop the full nameplate-rated capacitance value. And then there is also the size factor. Higher-voltage electrolytics for the same capacitance rating will, of necessity, be physically larger and may not fit into the space/footprint of the original capacitor.Apparently advances in electrolytic capacitor design/materials, etc. seem to make physically smaller bodies than the same rating from decades ago.

author: james_s
author_rank: Super Contributor
timestamp: May 23, 2017, 06:46:25 pm
content: In the case of the Game Gear the original parts are SMD electrolytics. The replacements are not critical, some of them do depend on having enough ESR or you end up with a washed out picture on the screen but reasonable quality SMD electrolytics tend to work just fine. Going up a step or two in the voltage rating is not going to be a problem here, just don't try using for example 160V capacitors when you only need 16V.

author: silviasol
author_rank: Regular Contributor
timestamp: May 25, 2017, 03:56:37 pm
content: Ebay auctionhttp://www.ebay.com/itm/281523193590?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AITThey seem to be from mouser, just the cheapest version of nichicon or panasonic caps he could find.I went ahead and spent 2 hours making a mouser order. Mine are smd caps instead of caps with leads. This way no fussing around with making the caps fit inside the case away from other stuff that gets in the way when closing the unit. Spent the time to get the correct height, lead/pad spacing and pin holes, should work out nicely. Now to buy more parts game gears.Quote from: Richard Crowley on May 23, 2017, 06:36:40 pmThere are two caps that are .47uf 50v. No advantage trying a lower voltage on those?

author: james_s
author_rank: Super Contributor
timestamp: May 25, 2017, 04:53:17 pm
content: Probably not, at 0.47uF it's probably hard to find electrolytics rated much less than 50V. They'll be fine.

author: Gyro
author_rank: Super Contributor
timestamp: May 25, 2017, 05:33:56 pm
content: Quote from: silviasol on May 25, 2017, 03:56:37 pmIf space permits, it is sometimes worth going to a higher voltage rating just to get a bigger can size. The smallest ones are more prone to drying out (hence the difficulty in finding lower voltage .47uF caps). You will often find different life ratings in the manufacturers' datasheets based on whether the can is above or below a certain diameter.

author: james_s
author_rank: Super Contributor
timestamp: May 25, 2017, 06:40:37 pm
content: Either way it hardly matters, this is a handheld video game, not mission critical avionics or something. The original dirt cheap crappy SMT electrolytic caps lasted what, 20 years before they started failing?

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 25, 2017, 06:57:59 pm
content: Quote from: silviasol on May 25, 2017, 03:56:37 pmWhat "advantage" are you seeking? Is there some problem you are trying to solve?What sort of "improvement" do you think you could accomplish from "upgrading" the power filter capacitors?Sorry, but it all seems pretty silly.

author: silviasol
author_rank: Regular Contributor
timestamp: May 26, 2017, 01:22:00 pm
content: Quote from: Richard Crowley on May 25, 2017, 06:57:59 pmWell I hear that running them on battery power kills the caps faster then running on ac power, is that not true?Quote from: james_s on May 25, 2017, 06:40:37 pmI think they lasted 10-15 years. I bought it in 2007 and just stuck it in storage because the screen was too dimm, I thought I got ripped off. Recently I read how people change the caps on them to get them working again so pulled it out of storage and fixed it, and now runs just like new. These sell for $50 to $60 with the caps replaced and you can get them for $10 each on ebay broken so can make some money on them.

author: Richard Crowley
author_rank: Super Contributor
timestamp: May 26, 2017, 01:30:07 pm
content: Quote from: silviasol on May 26, 2017, 01:22:00 pmI can't imagine any scenario where that could be true.Are the caps "dead"? By what method did you determine that? Or are you just looking for busy-work? One of my favorite quotes came from an old IBM mainframe service manual...QuoteOr in more colloquial terms: If it ain't "broke" don't attempt to "fix" it.

author: silviasol
author_rank: Regular Contributor
timestamp: May 26, 2017, 01:41:25 pm
content: The caps are bad on just about every game gear now. Just search game gear capacitors, it is a huge issue. I went to a pawn shop to pick up two of them, they both had bad caps, one no sound and one the screen was dim(like mine). It was funny because the guy would not go lower on the price until I started to walk out of the store.

author: james_s
author_rank: Super Contributor
timestamp: May 26, 2017, 05:05:22 pm
content: I think I paid more than $10 for mine, I should buy another to have a spare before they get hard to find. Always liked that system, my little brother had one when we were kids. The only problem is the thing ate AA batteries like popcorn. Fortunately modern NiMH cells work pretty well.

author: Zero999
author_rank: Super Contributor
timestamp: May 26, 2017, 05:17:53 pm
content: Quote from: silviasol on May 25, 2017, 03:56:37 pmI'd be more tempted to swap them with film or ceramic but the capacitance declines with bias voltage with some crap dielectrics.

author: helius
author_rank: Super Contributor
timestamp: May 26, 2017, 05:49:45 pm
content: Quote from: silviasol on May 23, 2017, 04:49:12 pmFish oil is non-polar, which would not be of any use whatsoever in an electrolyte. The fishy smell comes from amine salts of boric acid, which usually is present in miniature electrolytics.Similar rumors surround products like WD-40, which also doesn't contain fish oil despite its smell. Fish oil very rapidly rancidifies (which you will notice at any outdoor fish market) and is therefore not much use as a chemical ingredient.

author: james_s
author_rank: Super Contributor
timestamp: May 26, 2017, 07:20:41 pm
content: Quote from: Hero999 on May 26, 2017, 05:17:53 pmThat would work for some of them, but the Game Gear relies on the ESR for others. I learned the hard way by replacing them all with ceramic and tantalum and ended up with a washed out picture. Actually it could have been the reduction in capacitance with DC voltage, not really sure, but electrolytic worked.

author: silviasol
author_rank: Regular Contributor
timestamp: May 27, 2017, 10:15:48 pm
content: Quote from: james_s on May 26, 2017, 07:20:41 pmOh you have one? Probably don't need to worry about them becoming rare, there are so many on ebay. Virtual boy is what to get before it is gone. I have two right now and looking for more. The problem with them is a flex cable that comes unsoldered and one or both screens wig out. It was soldered directly to the board(is that called hot press?) and looses it's hold. The fact that the cable bends 90 degree's and is only held on by the solder is probably what is killing them. Also the one I have that works, the other has no power for some reason, has no sound and really bad sound with headphones. Waiting for my extra long security bit to be delivered to hopefully fix it. The thing is just awesome though, even though very uncomfortable to use.

author: retrolefty
author_rank: Super Contributor
timestamp: May 27, 2017, 11:51:08 pm
content: Quote from: Richard Crowley on May 26, 2017, 01:30:07 pmWell that would put the audiophool vendors out of work.

author: james_s
author_rank: Super Contributor
timestamp: May 28, 2017, 01:14:14 am
content: My friend had a Virtual Boy, I played with it a couple times, never really interested me. It's technologically cool but the display gives me a headache and since I never had one as a kid it's not something I'm nostalgic about. I did have a Game Gear though, spend quite a bit of time playing it back in the day so I picked up another one a few years ago.

author: silviasol
author_rank: Regular Contributor
timestamp: May 28, 2017, 02:29:34 pm
content: Quote from: james_s on May 28, 2017, 01:14:14 amThey are pretty cool. I actually play my game gear more then my new nintendo switch. I have the adapter that has the magnifying lens on it, can't play without it. Looks just ridiculous though, lol. It is called "super wide gear".

author: meeko
author_rank: Contributor
timestamp: May 29, 2017, 05:23:37 pm
content: Quote from: silviasol on May 28, 2017, 02:29:34 pmI've got one of those for my Game Gear, too. Yeah, makes a big difference in the playability. It doesn't fit properly with the adapter to play Master System carts; the spring clip hits the adapter. I can't remember if it cleared the TV tuner...I never had a problem with it eating AAs, because I mostly used it in the car, plugged into the cigarette lighter, or at my Grandparents' place, plugged into the wall. If I did want to use it elsewhere, I had the (NiCd) external battery pack, too. It weighed a ton, and was kind of a pain clipping it to your belt and having the wire trailing up to the unit, but I seem to recall the battery life from it was fairly decent, at least until the cells started to crap out from age/cycles...

author: silviasol
author_rank: Regular Contributor
timestamp: May 31, 2017, 02:46:23 pm
content: Quote from: meeko on May 29, 2017, 05:23:37 pmI just got one in with the nicd battery pack, the one that bolts to the back of the unit but still loose and swivels a bit. And it actually works, I couldn't believe it! This one also had the latest va5 motherboard in it so only about maybe 23-24 years old instead of 26. Now I have this huge... thing of a portable game system, and I love it

author: silviasol
author_rank: Regular Contributor
timestamp: June 09, 2017, 08:19:41 am
content: Ok making one more mouser order. I got a bunch more game gears in and the smd caps only work on boards that do not have a ton of electrolyte leakage, the pads are so crusty it is best for leads so I don't have to futz with scraping/cleaning the pads. I am going all out with all 5000 hour caps this time. Not as many of the 5000 hours. Just to confirm any higher voltage doesn't matter, only option for 68uf 6.3v is a 25v capacitor.

author: helius
author_rank: Super Contributor
timestamp: June 09, 2017, 08:53:53 am
content: Operating an electrolytic at below its rated voltage may result in the dielectric becoming thinner over time. The consequences would be the capacitance and leakage both increasing over thousands of hours. This normally is not a problem. It shouldn't have much effect on the lifetime.