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Need help with choosing proper replacement Capacitor

Need help with choosing proper replacement Capacitor

(OP)
All, First thanks for any help you can be!

I am working on repairing a laptop given to my son. The problem I am having it trying to find the correct capacitor to replace the bad one. If you want to know how I know it is bad, well.... It was rolling around inside the laptop. Figured that was the first clue something was wrong with it. thumbsup

Well, I know that the capacitor is a SMD, 2.5V, 390uf, approx 6mm dia and 6mm high but beyond that I am not sure... I have tried to search for the rest of the info on the capacitor but I can't find anything that is at all helpful. Since this is going on a computer circuit board I wanted to be sure I didn't put something back on that would possibly damage it any further. The main problem is the shear volume of options available for the few values I know. I have attached a pic showing the printing on top. If anyone can tell me what I should be looking for that would be great!

Thanks again!
John

RE: Need help with choosing proper replacement Capacitor

That voltage is fairly freakish. You're probably going to have troubles getting that specific cap even if you find it. Typically I'd spend about an hour searching for that specific one so I could read its specs to match it with a replacement. You can usually do it using colors, and ultimately the ID code 2L2. Likely a Nichicon brand.

As rare as 2.5V 390uF are I'd just try one and see what happens.

Possible Replacement


Check dimensions.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Need help with choosing proper replacement Capacitor

(OP)
Thanks Keith! I spent quit some time trying to find anything I could related to the 2L2 with no luck at all. That's why I turned here.

I know just enough about circuits to be dangerous and to be able to fix fairly straight forward problems. My concern with this is that I just don't know how far off I can be on the tolerance, ESR and ripple current before I hurt something. I just don't know how sensitive the circuit is or if it will even really matter.

I had several picked out that I was going to order and just try but thought I better get some advice first!

Thanks for the help!
John

RE: Need help with choosing proper replacement Capacitor

Have you tried testing and reattaching the capacitor you have? If you do need to replace the capacitor it might be easier to get one with leads on it so you do not need any special tools.

RE: Need help with choosing proper replacement Capacitor

Hi John,
I've found that replacing caps works on things about 1/2 the time. Just a warning you could replace the cap and still have nothing.

Compo has a good point, do the leads look OK on the rattler? If so it could just have been bad solder pasting at the original assembly.

Otherwise you can keep searching for which one that actually is. The hard part is that major players like Nichicon aren't real good about describing their marking codes. Also caps come and go so you may may not find that cap in any of their current documents.

My take is that that cap is probably nothing special, so just buy-an-try.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Need help with choosing proper replacement Capacitor

I've found the easy way to repair a laptop is to go to eBay and buy the part I need new or used (keyboard, motherboard, display, CCFL backlight, etc).

RE: Need help with choosing proper replacement Capacitor

(OP)
Thanks all! You have been very helpful! The cap that came off only has the tiniest of leads left on the bottom (maybe 1mm). It broke off.

Keith/Comcokid, I figured for a few bucks worth of caps it was worth it to try and fix it. If it works great, if not I'm out a couple of bucks and a few evenings. I have fixed a number of flat screen TVs that either would not turn on or wouldn't stay on by just replacing bad caps, so I figure it's worth playing with. Besides if I do fix it, dads a hero! 2thumbsup

Compro, that is a good suggestion. I may try that first.

Again, thank you all for your time!
John

RE: Need help with choosing proper replacement Capacitor

Keep us posted. We're always interested in outcomes of this type.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Need help with choosing proper replacement Capacitor

(OP)
Hi all, just a follow up to let everyone know how things went...

I ended up ordering 3 Caps from Mouser that I thought would be the best matches (based on the suggestions above and just sorting through them). In the end when I received them I picked the one that had the closest color to the old one! Very scientific I know but there just didn't seem to be a big difference, so I just needed to pick one to start with.

Anyway, the final result was a working computer. thumbsup2 It took two times for me to get it right. The first time I didn't get a good solder joint on one of the leads. Unfortunately I didn't see it until after I reassembled it, tried to turn it on (and it didn't work) then took it all back apart. The second time I was a bit more careful!

My son is very happy! thumbsup

Thank you all again for the help! thanks
John

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