ok to use 1500 uf to replace 820uf?

[berniedd]

Asus P5V800-MX mobo keeps on hanging, has many 820 uf 10v bulging caps. About 12 of them all over the board, and I guess I'll be replacing all of them, even those not yet bulging. All I have right now are 1500 uf Samxon caps. I think I'll be okay with this 83% increase in capacitance; does anybody think otherwise?

[Player2]

Re: ok to use 1500 uf to replace 820uf?

That sounds like way too much of an increase to me. Hopefully someone more knowledgeable than I can confirm/deny this, but generally I try to keep the capacitance within ~20% of the original if I absolutely must use a different size.

[c_hegge]

Re: ok to use 1500 uf to replace 820uf?

I agree with Player 2. Try to keep the capacitance the same. If the manufacturer used that capacitance, it was probably because the circuit was designed for it. A small increase or decrease may be ok (no greater than 20%), but going from 820 to 1500 is too much of an increase and not recommended.

[Topcat]

Re: ok to use 1500 uf to replace 820uf?

it would probably be ok. I've replaced 820uF caps with 1000uF caps many times, never had any issues...but I've never gone that high.

[NxB]

Re: ok to use 1500 uf to replace 820uf?

It would be fine. I think you are safe up to 2x of V and uF. A slightly higher rating is ideal. I'd order 1000uf caps. Make sure they are low ESR caps.

[MegaOne302]

Re: ok to use 1500 uf to replace 820uf?

Yes, don't worry it'll work fine. I've done it on a few motherboards and LCD inverters with no problems. Just make sure the temp rating (usually 85c or 105c) meets or exceeds the original. Also, if they're close to each other make sure you have the space before you start soldering.

[NxB]

Re: ok to use 1500 uf to replace 820uf?

If you use general purpose caps it will run worse. I'd definitely check out the datasheet.

[PCBONEZ]

Re: ok to use 1500 uf to replace 820uf?

If the ESR is the same or less and the Ripple is the same or more and they are 105c Temp caps then it will be fine as long as you don't have SO MANY that the inrush current when you turn on the power supply trips it back off by way of tripping off the over current protection feature.

[berniedd]

Re: ok to use 1500 uf to replace 820uf?

If the ESR is the same or less and the Ripple is the same or more and they are 105c Temp caps then it will be fine as long as you don't have SO MANY that the inrush current when you turn on the power supply trips it back off by way of tripping off the over current protection feature.

I guess the psu would have to be rather hefty then to prevent it from tripping off.

[gdement]

Re: ok to use 1500 uf to replace 820uf?

I'd test the locations with a multimeter and figure out what's in parallel. Combine that with ESR info from the datasheets for the old caps and new ones. Depending what you find, you maybe can just install caps at certain positions instead of all of them.

[PCBONEZ]

Re: ok to use 1500 uf to replace 820uf?

That's not what I was trying to say.
"If you replace ->SO MANY<-"
- Can't say what 'so many' [too many] is on any given board.
Something you just have to try to find out.

I can't see what you are looking at or have.
Are all these caps on the same rail?
Are they all VRM. Some VRM and some not?
Are any PI filters with a different size cap on the other side of the inductor?

Caps on boards have an acceptable range based on the reference design board.
For example the reference design your board was built to -might- say something like 820 to 1500 uF, or it might say 330 to 820 uF. [In other words the caps you find installed might be at the upper or lower end of the acceptable [design] range.

A cheap 'gutless wonder' PSU or one that's barely enough for the system might have problems if you are pushing it.
Probably not a problem here, but traces on circuit boards to have current limits and they can burn in half just like an overloaded wire.

I saw a thread somewhere where someone upped a bunch of 1000uF to something like 3900uF or 4700uF [long while since I read it] and the system wouldn't boot with any PSU.
On the other hand I've seen isolated 'experiments' where going up drastically in uF worked fine. [Though seldom with that many caps.]

Going 820-1000, 1200->1500, 1500->1800 or similar 'up one size' is well tested by many and can be called safe with some level of confidence.

Odds are you won't have a problem either but what you are doing is not well tested so don't take all the "it SHOULD work" comments as "it WILL work".
-
It SHOULD work, yes. But no guarantees.

I just didn't want to leave the idea in the thread that upping uF by large amounts is 'universally okay'.
.

[berniedd]

Re: ok to use 1500 uf to replace 820uf?

PCBonez, most of these caps are Vcc filters "guarding" specific parts of the mobo: each PCI slot has one of them, and so do the USB ports at the back of the board, the Keyboard port, the AGP slot, etc. No, none of them are used in conjunction with an inductor.

[PCBONEZ]

Re: ok to use 1500 uf to replace 820uf?

It SHOULD work, yes. But no guarantees.

[MXM]

Re: ok to use 1500 uf to replace 820uf?

im replacing 820uf - 4v with 1000uf - 16v... whats your opinion? theyre all close to the processor....

[PCBONEZ]

Re: ok to use 1500 uf to replace 820uf?

At 4v those sound like CPU VRM output caps. [Vcore - aka CPU Vcc.]

Provided that you do not go to a higher ESR or lower Ripple rated cap, 820->1000 uF should work out fine.

.

[Topcat]

Re: ok to use 1500 uf to replace 820uf?

im replacing 820uf - 4v with 1000uf - 16v... whats your opinion? theyre all close to the processor....

Are they lytics that have vented or polymers? If they're polymers, its unlikely they're bad anyway. If they're VRM outputs, you could use an 820uF 2.5v polymer safely most likely (depending on the CPU's core voltage).

Post up a pic if you can.

[MXM]

Re: ok to use 1500 uf to replace 820uf?

Thank you both.

[berniedd]

Re: ok to use 1500 uf to replace 820uf?

Long time no see, but here's an update, guys. I went ahead with the 1500 ufd replacements and the mobo's been running great for the last 1.5 years.

[Topcat]

Re: ok to use 1500 uf to replace 820uf?

^
Ahh thanks for the follow-up! I figured it would be ok!