Help identifying a Capacitor

[saturday tech noob]

Hi all,
I have a toshiba a100 that i started taking apart a year ago and finally found the time to get back to it. I think it used to just lose power all of a sudden. I just checked all the caps on the MB with an ESR meter and I have found a cap that is testing 10 times worse than the 5 other caps on of the same type the board.
I have spent a lot of time trying to find out what type of cap it is so I can order a replacement but it doesn't seem to conform to any marking scheme that I can find. Have provided a pic. It is about 3mm by 4mm and hard to read. I think it says 476G and U072P. Can anybody help me work this out so I can order a replacement?

[tw2005]

Re: Help identifying a Capacitor

well to get you started 476G, 47 x 10^6pf = 47000000pf=47uf

not sure about type, voltage or tolerance but I'm sure someone will .

[mariushm]

Re: Help identifying a Capacitor

That's a tantalum capacitor, be very careful when replacing it because the | sign represents the POSITIVE with tantalum capacitors.

The stuff the capacitor is connected to is a dual p-channel mosfet capable of maximum 20v running through it, so the voltage on capacitor should definitely be less than that.

The whole thing there is probably a sort of dc-dc converter, judging by the inductor, mosfet pair and low esr tantalum capacitors. The small chips to the right of the mosfet are probably (a) dc-dc controller chip(s), which turns on and off the mosfets to control the amount of energy going into the inductor and implicitly output of the converter.

[saturday tech noob]

Re: Help identifying a Capacitor

well to get you started 476G, 47 x 10^6pf = 47000000pf=47uf

not sure about type, voltage or tolerance but I'm sure someone will .

Thanks for the reply tw. I was confused by the 6 because I looked at a few guides on reading capacitors and they said that 6 and 7 are not used. I hope your right because it makes it a lot easier. Can anyone else confirm this is correct?

[saturday tech noob]

Re: Help identifying a Capacitor

Sorry for the double post. I didn't see the multi quote button.

Thanks for all the technical help mariushm. It would take me a lot of reading to find all that out.

The stuff the capacitor is connected to is a dual p-channel mosfet capable of maximum 20v running through it, so the voltage on capacitor should definitely be less than that.

I read that the voltage on a capacitor it is the maximum it can handle without dying so it is advised to use one with a higher value than the voltage in the circuit. I am a big noob when it comes to this kind of stuff. Is it different for voltage conversion?

[mariushm]

Re: Help identifying a Capacitor

The voltage written on a capacitor is the maximum the capacitor can tolerate. The actual voltage in the circuit is normally smaller.

Just the same, mosfets have a maximum voltage specification, meaning the mosfet will be damaged if the voltage exceeds that value. So from there, it's logical to assume the voltages in the circuit should be smaller than those maximum values.