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I need capacitor help?

I have an issue with some bad capacitors and I have read conflicting information on the matter and hope someone can help me. I have 2 different caps that have to be replaced one is 10v 1500 microfarad and the other is 6.3v 1500 microfarad. First can I use the capacitors that are all silver in color with no plastic sheating (not sure of the name; pics included) because I have a bunch that are 6.3v 1500 microfarad? As for the other capacitor I do not have that exact value, I have 10v in 1000 microfarad, 1200 microfarad, and 2200 microfarad, but I have one that is 16v 1500 microfarad, what I'm mostly wondering is what can be changed the voltage or the capacitance? And would one of those work for the 10v 1500 microfarad capacitor I need or should I just ebay it? Due to a postal strike I may not get it for a while and like most I needed it fixed yesterday. I am fairly new to trying to learn electronics and hope someone can shed some light on my problem.

Picture of I need capacitor help?
silver capacitors.jpg
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orksecurity6 years ago
In generally, unless you COMPLETELY understand the circuit, never replace a capacitor with one that has a lower breakdown voltage rating; you may cook it. Higher is almost always OK; it just may be bulkier and the spacing between the leads may be different (which you can usually kluge around).

You also want to use the same type of capacitor. Both the black and silver appear to be electrolytic capacitors, so you should be able to replace one with the other. The black ones have partly insulated cases, which is a Good Thing if there's any risk they might touch other circuitry but otherwise doesn't matter.


Make sure you get the polarity right; electrolyics care about which terminal goes where. I can't tell from the photo how the units in the second picture are marked for polarity, but they must be. Take careful note of how the one you remove is oriented and make sure the new one goes in with the + and - terminals connected the same way.


You're aware you can get many common capacitors from stores like Radio Shack, right? (An old-style electronics repair shop is an even better bet.) Or from companies which specialize in electronic parts, such as Digi-Key? eBay isn't always the cheapest, easiest, or fastest solution, and definitely isn't the most reliable...
DavezDesignz (author)  orksecurity6 years ago
Thank you for such a quick reply, now I just want to make sure i understand, I figured I could not go lower but was maily concerned on what could be changed as I had read conflicting information. I understand from what you are saying is that the voltage can be changed and should be higher if not exact. I have also read in here about someone replacing a 1000 microfarad capacitor with a 1200 microfarad, so can they both be changed (voltage and capacitance) or just one or the other?

Thats what I thought about the 2 variations of capacitors but was unsure due to not finding enough information, as for the insulation would it be okay to just use some shrink tubing for insulation? I have replaced quite a few capacitors on motherboards in the past and those computers are actually still working, but I have always had the exact values but right now I am in a bind and need to use what I can.

As ofr a place to buy them, well, basically there is nothing here anymore. We used to have a radioshack but it got sold to The Source and now they basically have nothing for electronic components. As for stuff that has to be mailed or couriered, there is a postal strike here in canada, and paying courier fees for 2 capacitors isn't really justifyable to me when I have so many old components laying around here that are still in good shape, Thank you for your help it is greatly appreciated
VERY rough analogy -
Voltage in this case is like pressure...if you go over the voltage rating, it will pop, or in a capacitor's case, let the magic smoke out.

Farads is the total capacity. Like the gas tank on a car - you can replace it with a bigger or smaller one, and it should still work, but the overall range of the vehicle will be affected, and the added weight might have unexpected consequences.
+1, in general... but whether a larger capacitance (more microfarads) is acceptable really depends on what the circuit is using that capacitor for. If it's part of a resonant circuit (filter or oscillator), changing the capacitance will change the frequency response. In a power supply, increasing the capacitance is generally not an issue, but in other uses it could be.

You're unlikely to damage anything else in the circuit by having a component be 20% off its rated spec, so I'd say you can go ahead and try it. But the presence of the inductor toroids makes me suspect this might be a tuned circuit and it _might_ really prefer the right value. What's it part of?
DavezDesignz (author)  orksecurity6 years ago
motherboard for an ibm...
OK, in that case they're almost certainly being used as filter capacitors and slightly larger will probably do no harm.
DavezDesignz (author)  orksecurity5 years ago
slightly larger voltage? i tried a 16v 1500uf but it didn't completely work (the computer would turn on but it is not giving me any video) :( would a 10v 2200uf work in place of the 10v 1500uf or should I use a 10v 1200uf as that is the closest values I have?
As noted earlier: Higher voltage rating is generally harmless. Different capacitance value may not be, depending on the circuit.

Without seeing the circuit -- preferably the circuit diagram -- we're operating on best-guess here.

Are you sure you installed the new cap with the right polarity?

How certain are you that the capacitors, and ONLY the capacitors, are the actual problem?
DavezDesignz (author)  orksecurity5 years ago
well I went and ordered the proper capacitors I needed and installed them, but as you said there is something else wrong I guess. now when I plug it in it comes on (when before the power light would just fade on and off slowly) but have no video and the fans sound like they are pulsing. Any idea what would be causing this kind of behavior or what I could check for, or should I just call it quits? As I said before I have replaced capacitors in PPC's many times before, actually the computer I am on right at the moment I had to replace about 7 capacitors about a year ago and it has been running great since I had replaced them but the computer I am trying to fix is getting a little frustrating. If anyone can give me any ideas or things to try please do it is greatly appreciated.
DavezDesignz (author) 4 years ago
You all had great answers and I learned from them... Thank you all for your time... it is appreciated.
AndyGadget6 years ago
 
Those caps in the first picture look very familiar to me.  At work I've had a batch of Lenovo PCs where there's been over 20% failures (25 machines) due to capacitor breakdown.  It looks like Lenovo used a dodgy batch around 3 1/2 years ago and they've been failing ever since. 
I can see yours is a different machine, but you may find them very hard to replace as many high density boards have power planes embedded inside them, so any heat you apply to the legs is immediately conducted away making the solder very hard to belt.
That job needs a high powered soldering iron - one with enough welly to stay hot while desoldering. 80-100W kind of power.

Steve
 
Yep, high wattage iron and applied to both legs at once, using your third hand to gently pull the component from the other side.
DavezDesignz (author)  AndyGadget5 years ago
30W has worked just fine every other time I have replaced capacitors and up until this computer have never had an issue, I believe this computer has more problems than just the capacitors.
 
I'm just going by my own experience with the soldering, but if you're getting random reboots, crashes and failures to boot up then those caps are to blame.  I'd put money on it.
DavezDesignz (author)  AndyGadget5 years ago
unfortunately the caps are not the only problem it seems... I posted here earlier about the new issues ... if you can help please do ... thanks