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Ive got some caps to replace and need a couple of hints

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knoober

Member
Joined
Mar 18, 2015
So I have finally seen with my own two eyes a set of bulging capacitors on an old socket 478 mobo. Its not the biggest deal in the world because the board is old and OEM and it was free, but I do want to put it to work. My guess is that it might be better to practice soldering skills on a cheap/free board that I dont necessarily need, and then I might have some skills under my belt for when an important cap needs replacing. We shall have to find out if my solder skills are up to snuff :) These caps are marked on the bulging top with "HD r3 1500 6.3V" and no other visible markings. There are 4-5 of these and 2 of another kind with bulging tops. The board still works as of now BTW, so Im not in a super hurry. I will likely complete the replacement when I begin to see issues.

Now to the part I have questions about:
1) are there standard values of capcitors that are used on a large number of motherboards so that I might make purchases with that in mind rather than running back to the "store" every time I need a cap or two ?

2) I know from my PSU adventures that not all caps are created equal. Is it worth it to replace these bulging caps with a quality brand while leaving the original caps in place? Is it a worthwhile pursuit to just replace every cap on the board while I have the soldering iron out (poor soldering skill not-withstanding) ? And what I mean by worthwhile pursuit is: significantly greater longevity and performance.

Thanks in advance :)
 

Nebulous

Señor Senior, Senior
Joined
Oct 11, 2002
Location
The Empire State
They're easy to replace. I've replaced hundreds. Just remember they only go in one direction and have a solid stripe marker that goes in one way. I would replace all the bulging caps with new ones. The new ones you buy are better quality then the ones that are massed produced for motherboards at that time.

You can order them from amazon on the cheapo ;)
 
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JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
If you are in there, I would replace ALL of them.

These types of caps naturally go bad with age.
 
OP
knoober

knoober

Member
Joined
Mar 18, 2015
If you are in there, I would replace ALL of them.

These types of caps naturally go bad with age.

that was my rationalle, but I have seen with other projects (cars mainly) that this type of thinking can be lead to unnecessary work. I will have to tally the cost of all the caps and see if the cost is worth it for the board.
I mean there isnt any problem dropping a $10 on a legacy board, but that is kind of pushing it for an OEM board. Now if this was a premium overclocking board or something.... :)

Thanks for the help guys!
 

Alaric

New Member
Joined
Dec 4, 2011
Location
Satan's Colon, US
Get caps rated for 105C temperature. Generally the same price and much longer life. If the caps are in the audio section, spend the extra few cents (literally) on some good nichicon caps. Your ears will thank you. And yes, all the mobo caps I've seen are standard values so no need to hunt down oddball values.
 

Silver_Pharaoh

Likes the big ones n00b Member
Joined
Sep 7, 2013
6.3v caps are usually used for the 5v rails, 20v or 25v as well as 16v can be used for the 12v rails.

For replacing caps, keep the capacitance (marked in uF on the caps) the same or a bit greater and the voltage must always be the same or greater. Try to keep the ESR close to the original too, though I don't think it's as important, UNLESS this is for audio equipment, Then lower ESR=Better.

To unsolder them, get in there and heat fast. You don't want to sit there on the part with your soldering gun as you may damage the power plane if you heat it too long. (Power plane = thick copper parts that deliver voltage to the mobo's components). Once the part is removed use some clean stranded wire (like 18Ga) with a bit of flux on the end to remove the old solder from the cap's holes. Just place the wire over the hole and heat the wire with the iron. The old solder should be sucked right into the stranded wire.

To replace, just pop the new cap in making sure the polarity is correct and solder the legs well. Trim flush afterwards and you're done!

I've replaced a handful of caps on my Pentium III server over the past year. I don't replace them all at once. When I see one bulge I replace it right away. I bought these Rubycon caps to replace my bad caps, specifically, the ZLH series. 6.3V 1200uF 10,000 hour lifespan 105C. These are nice caps. I figured if you're going to replace them, might as well buy good caps and replace them once :D


EDIT: Here are the caps I would use to replace yours: http://www.digikey.com/product-detail/en/rubycon/6.3ZLH1500MEFC8X20/1189-2352-ND/3563474
Just make sure your spacing lines up. The ones I linked have the legs 3.5 MM apart.
 
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OP
knoober

knoober

Member
Joined
Mar 18, 2015
Isnt it funny how the clearer the explanation the more questions you have? :)

Just one really though: power plane =

images1.jpg
?

I have always tried to be careful of those just as a general rule, but if that is what you are talking about then that may be why some of my stuff doesnt work anymore. My goal is always to just cover to the edge of that circle with the solder.... but you know... it doesnt always turn out that way. Like I said, thats why I practice on gratis hardware :D
 

Silver_Pharaoh

Likes the big ones n00b Member
Joined
Sep 7, 2013
Isnt it funny how the clearer the explanation the more questions you have? :)

Just one really though: power plane =

View attachment 183363
?

I have always tried to be careful of those just as a general rule, but if that is what you are talking about then that may be why some of my stuff doesnt work anymore. My goal is always to just cover to the edge of that circle with the solder.... but you know... it doesnt always turn out that way. Like I said, thats why I practice on gratis hardware :D

I beleive its the larger light green pads in your picture. That's what I've always thought they were.

But you are right, you want to cover those little circles :)
Always helps to practice before hand! Dead or worthless PCB's are great for this.

When I first soldered in new caps, I had a large 140 watt soldering gun and I ended up getting solder on my RAM pins!!! :escape:
Definitely use a 40 watt iron with a nice fine tip.
 
OP
knoober

knoober

Member
Joined
Mar 18, 2015
While we are on the subject of caps... I've noticed on more than 1 gpu and board that there are spots etched for additional caps. Has anyone ever successfully achieved additional performance by adding in the correct caps in the correct places? It seems I've read that these are usually because the same pcb is used for higher end card/board, but those spots would be filled appropriately on the more robust boards
 
OP
knoober

knoober

Member
Joined
Mar 18, 2015
Well it took a while for the caps to get here and it's kind of slow going but I've got 2/5 in and it still boots! :)

I'm testing in between every replacement so I can know which one I screwed up on, but TBH if I haven't killed it yet I think I might get through this :) I've chipped the pcb 1x so far and was pretty nervous, but I'll keep my fingers crossed and bottle of Flux close :D
 

JrClocker

AKA: JrMiyagi
Joined
Sep 25, 2015
Use the Flux knoober...use the Flux!

Embrace the power of the Dark Side of the Flux!