capavitors - Page 1
Forum section: electronics / beginners

author: moontide
author_rank: Contributor
timestamp: November 26, 2018, 01:17:29 am
content: I have a few simple questions good sirs....I have an old laptop and it needs new caps. Can I go ceramic instead of electrolitic. Is 10 ceramic 100 nf similar enough to 1mf. (I sure home my basic conversion ranges are correct, lol)Basically I'd like to go ceramic because this is an antique and I like to put a long solution in it....2nd question.If I have a motherboard, can I replace the cap with I higher value.... I think Dave touched on this but not sure what video......Anyway, thanks for lookingTylerUSA

author: moontide
author_rank: Contributor
timestamp: November 26, 2018, 01:20:07 am
content: Damn, I f'ed up the title.... Lay off the suds Tyler....

author: tpowell1830
author_rank: Frequent Contributor
timestamp: November 26, 2018, 01:24:24 am
content: Quote from: moontide on November 26, 2018, 01:20:07 amClick the edit icon, lower right of your post and change the title... it's legal.

author: ogden
author_rank: Super Contributor
timestamp: November 26, 2018, 01:25:25 am
content: Not a good idea to change output capacitor type. Power supplies usually are build/tuned for specific ESR of the output capacitor. If you replace electrolytic cap with low ESR (ceramic/polymer) cap, supply may become unstable.  Yes, you may increase capacitance - if you can't find exact replacement parts, but not too much, like < 2x original capacitance.

author: IanB
author_rank: Super Contributor
timestamp: November 26, 2018, 01:34:43 am
content: Quote from: moontide on November 26, 2018, 01:17:29 amIn general you should try to replace a component with one that is as similar as possible to the one you are replacing (in type, in rating, and in physical size). This is because the original design may have relied on certain characteristics of the part in order to perform properly. If you replace the part with one having different operating characteristics it may upset the design and may cause problems. (One exception is you may use a higher temperature rating for an electrolytic capacitor, and perhaps a slightly higher voltage rating too.)In some cases (for example with transistors), it may even by necessary to find new old stock of a vintage part in order to get an accurate replacement.

author: glue_ru
author_rank: Contributor
timestamp: November 26, 2018, 02:59:33 am
content: use the same kind, just go a bit higher on the voltage and make sure 105c rated (temperature)

author: spec
author_rank: Frequent Contributor
timestamp: November 26, 2018, 08:41:02 am
content: Hello Tyler,Quote from: moontide on November 26, 2018, 01:17:29 amJust a small point, 1mf is 1000uF. Your question should read, Are ten 100nF ceramic capacitors in parallel equivalent to a 1uF capacitor?The answer is yes but:Ceramic capacitors are a minefield, but as a general rule of thumb go for X7R dialectic, and go for as physically large ceramic capacitors as you can. Avoid small surface mount types.Most capacitors on motherboards are decouplers for digital chips, which you would be pretty safe changing to ceramics. The same goes for timing capacitors. But, as the other members have indicated, there are areas where the capacitor type is critical, some power supply capacitors for example.Quote from: moontide on November 26, 2018, 01:17:29 amYes, in most cases, with the caveats mentioned above.On a general note, it is understandable that you want to make your motherboard more reliable, by fitting ceramic capacitors in place of aluminum electrolytic capacitors, but, as the other members have said, you would be much better off just fitting new high-quality aluminum capacitors.Aluminum capacitors vary a lot in their reliability, performance and cost and it could be that the original capacitors fitted to your motherboard were not the best. Also, aluminum capacitors quality has improved a lot.My advice is to choose aluminum capacitors from a top tier manufacturer: Panasonic, Kemet, etc and buy your capacitors from a top tier distributor, like DigiKey, everyone's favorite distributor.The reliability of a capacitor is inversely proportional to temperature, the cooler the better down to around 15 Degrees C. So you could possibly improve the reliability of your motherboard by improved cooling. Also the lower the operating voltage the better. So if you fitted aluminum capacitors with a higher voltage rating than the originals that would also improve reliability. I would suggest that running an aluminum capacitor at 50% to 66% of it's rated voltage is a good compromise.And finally on to a subject that you have not asked about.There are three top failures with motherboards.The fans are not working at full efficiency, due to dry bearings or being clogged with debris.The thermal washer and grease between the CPU and heatsink have degraded and need to be replaced with high performance items.And the big one: degraded solder joints and tarnished connectors. Both of these happen with time and heat. So it is advisable to closely inspect all solder joints and reflow if necessary and burnish all connector pins if necessary.End of sermon.

author: moontide
author_rank: Contributor
timestamp: December 04, 2018, 10:04:17 am
content: Well, I'm happy to be here. These are great answers.So I'll replace with electrolitic of higher voltage rating... Temp too if possible. I dare not reflow chips and whatnot due to risk and wear.So I figure if I had the characteristics of each old cap, then I could tailor the ceramics to the same/similar characteristic.....perhaps do a mainly ceramic capacity with an electrolitic on top....Sounds like a lot of work for an 80 MHz Epson Laptop.....Electrolitic it is...Yah fans on mobos hurt soo bad after 5 years!

author: Kjelt
author_rank: Super Contributor
timestamp: December 04, 2018, 10:16:45 am
content: Actually I think it is a great title, some capacitors act like capuffitors when they get hot and old

author: moontide
author_rank: Contributor
timestamp: December 04, 2018, 10:24:58 am
content: I'm happy I haven't changed it....Like some kind of duel op amp with a capacitor.

author: moontide
author_rank: Contributor
timestamp: March 09, 2021, 03:55:52 am
content: So I have a little progress.........I replaced multiple caps in a dell motherboard. It looked like a couple were for memory and a couple were near backplane. A single was near a dummed down southbridge.All were electrolitic and they ramained as such. I went over or the same as per the listed farat. I made very reasonable connections.I turned it on.It posted.It froze on the progress bar at around 10%It kept freezing on the same spot as I could tell.I turned it off and walked away.6 months later it kinda glitched then worked fine.My assumption the computer needed time to understand the new state that it was in to be capible to take the complexity of electricity.and(or)The flux created a copper corrosion that acted as a micro cap that delay for power to be more smoothed. A new cap in a field of old could make a discrepancy in the dynamics of power regulation.I think it is a good question.