voltage difference limit?

[maximus7001]

Greetings. I was wondering how much higher voltage rating would be ok. The caps that need to be changed are 1000uF 6.3v and the replacements I can get for the easiest and cheapest are rubycon 1000uF 25v Y K . Will these do or are they too high voltage?

[acstech]

Re: voltage difference limit?

I don't think it would be a problem, but you might need to look at physical size, to make sure they'll fit.

[gdement]

Re: voltage difference limit?

The 25V rating won't hurt anything, but YK series capacitors are general purpose, not low ESR. Depending how the board is using the caps they might not work properly.

[Leung Kai-yan]

Re: voltage difference limit?

Greetings. I was wondering how much higher voltage rating would be ok. The caps that need to be changed are 1000uF 6.3v and the replacements I can get for the easiest and cheapest are rubycon 1000uF 25v Y K . Will these do or are they too high voltage?

Dear Friend,
Choose only those capacitors which ESR/impedance is low.

[chipper]

Re: voltage difference limit?

It's not a good idea to change capacitors on a PCB with capacitors that have a higher rated voltage , usually only the uF value can be bumped up , and not more than 80% of the original rated amount of uF. If you have a 6.3volt cap requirement and you use 25volt caps , the new caps will not run at the same rates up or down when running , this could cause instability problems or worse.

If 80% of the cap's original uF rating is bumped up 100% , you are entering the next ranges of caps that don't belong in those traces. Heat may be all that will result but is a tell-tale sign of a problem. Not to mention , it could change other voltage values on the mobo or component. Up or down.

[PCBONEZ]

Re: voltage difference limit?

>> It's not a good idea to change capacitors on a PCB with capacitors that have a higher rated voltage. <<

-> BOGUS!!!

It is in fact a standard practice!!

.

[arneson]

Re: voltage difference limit?

1000mf at 6.3 volt,
I would for sure jump to 10v
but up to 25v could mean they are way larger not just can size
but possably in lead size.
I know I would not be dremel drilling out holes
to fit the wrong part on a multi layer board.

[PCBONEZ]

Re: voltage difference limit?

That too.

[PCBONEZ]

Re: voltage difference limit?

maximus7001

Look at digikey.com
They sell 1000uF in a number of series' that are superior in esr and ripple ratings to YK.
They ship to canada.

[PCBONEZ]

Re: voltage difference limit?

What is this for?
What is original cap?
You may need to look at ripple rating/ESR too depending on what this is going into.

[They have links to data sheets too]
http://search.digikey.com/scripts/Dk...me=565-1630-ND
http://search.digikey.com/scripts/Dk...me=493-1707-ND
http://search.digikey.com/scripts/Dk...me=565-1486-ND
http://search.digikey.com/scripts/Dk...me=565-1878-ND

[chipper]

Re: voltage difference limit?

If running higher voltage capacitors is a good practice , then why not just install 50 volt or 100 volt capacitors all over the board , as they do come in all shapes and sizes?

I wouldn't exceed the voltage of any capacitor to any higher voltage , especially in specific areas where there are tiny onboard parts that may be overloaded by such an installation. I would say that it is perhaps not a good idea to more than "double" any capacitor's range.

Smoke is a tell-tale sign of too much voltage

[PCBONEZ]

Re: voltage difference limit?

The voltage stated in a capacitors ratings is a LIMIT not a goal.

What you say is idiotic.
- Examples right in your face:

16v caps on a motherboard are on 12v power. - NOT 16v power.

Both 10v and 6.3v caps on motherboards are used on BOTH 3.3v and 5v power.
- NOT 10v and 6.3v power.

10v is OFTEN used in place of 6.3v on BOTH 3.3v and 5v power because they are larger physically and tend to have lower ESR and higher ripple.
- 10v cap on 3.3v power is normal from the factory on some boards and in MOST PSU's.

Go find a 2200uF 50v cap and tell me how big it is.
- And how much it costs.
- Tell me how you are gonna stuff 10 of those in next to your heatsink on you mobo.

.

[chipper]

Re: voltage difference limit?

One good solid proof of not being able to change voltages is with fuses in your fusebox at home. Install a 15amp fuse in a 30amp socket and run the power to see what happens to the fuse , it will blow right away with no recourse for the fuse.

Most times the fuse will blow upon installation even though it is of the same voltage but the conduction plate inside the fuse is only rated to withstand 15amperes , not 30amperes. One other good example is your car's air conditioning fuse - it is usually one of the only 30amp fuses in the box , if you install a 20amp fuse temporarily , your heater/air fan will run slower than normal for a while , and then it will blow the fuse because current draw can reach 30amperes. (where the fuse can not run)

[Gianni]

Re: voltage difference limit?

Why are you talking about "One good solid proof of not being able to change voltages"?

One good solid proof of not being able to change voltages is with fuses in your fusebox at home. Install a 15amp fuse in a 30amp socket

You are comparing 2 fuses with different CURRENT CAPABILITY 15amp versus 30amp not different voltage rating.

I wouldn't exceed the voltage of any capacitor to any higher voltage , especially in specific areas where there are tiny onboard parts that may be overloaded by such an installation.

You can only overload a circuit when you place a CAP which is higher in uF and not in V rating compared to the original CAP.

Just my 2 cents
Gianni

[barefoot]

Re: voltage difference limit?

The Voltage is a Limit Rating. Nothing more nothing less. If the new cap is a higher rated voltage and there is room to install in the same spot it is ok to use, period. Its kind of like using a 1 gal pot for 1/2 gal water, any volume below 1 gal will work. You want to stay above the highest possible voltage the cap will ever see. Most high quality company's use 35% to 50% tolerance over rating to ensure stability. Low quality company's use only a 10% to 15% margin to cut cost. This is why Fisher & the like cost more but you get what you pay for.....

[PCBONEZ]

Re: voltage difference limit?

Chipper, you are a moron.

Going with you failed attempt at an analogy: Using a cap on a voltage UNDER it's LIMIT would correlate to using a fuse on a circuit that pulls LESS amps than the fuses' rated LIMIT. - With your numbers - 15 amps through a 30 amp fuse will not blow the fuse.

What I've told you is correct and very VERY VERY basic electrical knowledge.

.

[arneson]

Re: voltage difference limit?

This fell right off the edge of reality.
Fun to read but no more so than a Dr Suess.

[kc8adu]

Re: voltage difference limit?

One good solid proof of not being able to change voltages is with fuses in your fusebox at home. Install a 15amp fuse in a 30amp socket and run the power to see what happens to the fuse , it will blow right away with no recourse for the fuse.

Most times the fuse will blow upon installation even though it is of the same voltage but the conduction plate inside the fuse is only rated to withstand 15amperes , not 30amperes. One other good example is your car's air conditioning fuse - it is usually one of the only 30amp fuses in the box , if you install a 20amp fuse temporarily , your heater/air fan will run slower than normal for a while , and then it will blow the fuse because current draw can reach 30amperes. (where the fuse can not run)

sounds like someone needs a bit of study in basic electrical!
fan will run slower?
ROFLOL!

[chipper]

Re: voltage difference limit?

Why are you talking about "One good solid proof of not being able to change voltages"?



You are comparing 2 fuses with different CURRENT CAPABILITY 15amp versus 30amp not different voltage rating.




You can only overload a circuit when you place a CAP which is higher in uF and not in V rating compared to the original CAP.

Just my 2 cents
Gianni

To be more "specific" , lets look at how rectifiers work . Rectifiers convert AC current into DC current for distribution in circuits. "Specifically" - rectifiers will work differently depending on "how" they are set up and what current is made available to them. In fact , if the wrong current is supplied to a rectifier (which usually has paired IC's and a voltage regulator (3)) , the capacitors may never "unload" , causing them to burst. Meanwhile there has also been an abnormal taxing of power placed on the source power supply and it's attached components.

One other such example is on a tv's video board controller chips , if they receive the wrong current (voltage) , they will fail over time or in most cases be instantly damaged without recourse. If you read any of the PDF documents on specific IC's or any processor chips , a warning is usually at the end that explicitly tells you that their products "will-not" work properly or extensively in ranges other than specified by the manufacturer.

In conclusion if you hooked up a capacitor that was 100v to a regulator IC that is supposed to operate on the normal circuit voltage of 25v , the very first thing that will happen is the voltage regulator will run at maximum resistance full time and it will fail sometime shortly afterwards depending on the severity of the overload. Since voltage regulators are attached to dependant circuits for "reduced or regulated voltage" - they too can sustain damage or worse , they can cause a fire.

You can only get away with increasing the voltage flow or volume on something that has no other circuits depending upon the capacitor , like a single fan for example. But IC's are Integrated Circuits - not single circuits.

As far as comparing cars or anything else - if you installed a 100volt electrical supply to your 12volt car wiring , all of the insulation would heat up and eventually be burning until the wiring caused a failure of the system integration.

[chipper]

Re: voltage difference limit?

sounds like someone needs a bit of study in basic electrical!
fan will run slower?
ROFLOL!

Definately a fan with a lower rated fuse than what is required will run slower if at all , if the fan circuit depends on the fuse link for power.