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Old 12-20-2013, 10:18 PM   #1
bigjess007
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Default Dell Optiplex 780 SFF and AC235AS-00 PSU

Hey everyone,

So I know I'm working on my GX620's in another thread, however we just got a used Optiplex 780 SFF C2D Quad that we're going to start using (and probably stressing) a good bit, so before we put it in to service, I figured I better have a look inside.

The motherboard has the following caps I've identified.
Big ones in the middle: 1800uf 6.3V 105C FL [M] 05IIEY
Everywhere: 470uf 6.3V KY (M) 105C
Sporadically scattered: 120uf 16V 105C FM [M]
Between the ram: Rubycon 1000uf 6.3V A1023 105C PET
Oddball in the bottom right, only 1 of these and it's the only one that has a marker stripe on top: 220uf 16V KY (I think, that's all I can make out)
There's a few polymers near the CPU but I didn't include those.




None of them appear bloated (I know that doesn't mean anything) and interestingly only that one in the bottom right has the marker stripe on top.

From what I know, the FL and FM are Panasonic's and those are pretty rock solid (?) The Rubycon's are usually good too I believe. That leaves the KY's that are everywhere and I believe those are UCC caps.

Would anyone recommend a preventive recap of any/all on the motherboard? It was pretty clean when we got it, the fan under the hard drive was moderately dirty and I cleaned that up.



The power supply however worries me. It's model AC235AS-00






It has a couple of Ltec's, but the majority are CapXon caps. None are swelled, but they sure slapped em in, lots slanted. PSU wasn't filthy, but I did blow it out. I see lots of complaints about CapXon caps.

Does the PSU need a preventive recap?


Thanks again in advance, always great advice and knowledge around here.
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Old 12-22-2013, 08:55 PM   #2
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Don't touch the motherboard. KY is an excellent series...

Yes, absolutely re-cap the PSU. Keep in mind that caps don't necessarily bloat when they go out of spec and it is even possible that bloating is a symptomatic exception rather than a rule, if I am correct in my assumption that most caps do not in fact bloat when they go out of spec.

That chubby silver 6.3V 1500uF cap in middle of the board is a Capxon polymer... In my opinion it should also be replaced eventhough it's polymer. You know the drill.
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Old 12-22-2013, 09:11 PM   #3
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

I agree with mockingbird - the motherboard is fine but the PSU could use a recap. I wouldn't necessarily touch the sleeveless CapXon polymer in the PSU, but the other CapXon and Ltec caps should go if you want to have this computer worry-free for the next 10 years.
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Old 12-22-2013, 09:25 PM   #4
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Just a correction. I stated it was a Capxon polymer, but it is in fact made Elite. Datasheet
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Old 12-25-2013, 06:54 PM   #5
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Well glad to know the motherboard is fine. I don't like motherboard recapping's haha. Still learning, good to know United Chemicon KY's are good. They kinda puked KY's all over this board, I did not want to have to change all of them!

I kinda figured you were going to say recap the PSU. CapXon equals crapcon from what I've found round these parts

Here's my diagram:


Here's my research:
Code:
Cap	Brand	uf	Volt	D MM	H MM	Info on Sleeve:

A	CapXon	22	50	5	14	KM105C(M)	P1022
B	CapXon	1000	10	8	22	GF105C(M)	P1202	VENT
C	CapXon	10	50	5	14	KM105C(M)	P1024
D	CapXon	100	50	8	14	KM105C(M)	P1020	VENT
E	CapXon	120	420	18	32	KM105C(M)	P1024	VENT
F	CapXon	47	25	5	12	Can't see back side, assuming KM105C(M) looks like others
G	CapXon	47	25	5	12	KM105C(M)	P1020
H	CapXon	1800	16	10	24	GF 105C(M)	P1008	VENT
I	CapXon	1000	10	8	22	GF 105C(M)	P1020	VENT
J	CapXon	100	25	6	14	GF 105C(M)	P1022	VENT
K	CapXon	1000	10	8	22	GF 105C(M)	P1020	VENT
L	Ltec	1000	10	8	22	LYZ105C(M)	PET	0623D0
M	Ltec	1000	10	8	22	LYZ105C(M)	PET	0623D0
N	CapXon	10	50	5	12	KM105C(M)	P1024	VENT
Poly	Elite	1500	6.3	10	12	RP 130
I know the opinion is generally don't touch the main cap (E: CapXon 120uF 420V) however since CapXon is such a bad brand should I go ahead and change it? For a couple of bucks I can't see why not unless you guys think it really isn't needed.

And on the poly, what's the opinion of Elite caps? Again, if it's only a buck I'd rather just change it too and have totally fresh and completely new caps and hopefully not have to give this machine another look for some time.

Many thanks in advance!
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Old 12-25-2013, 06:55 PM   #6
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

So I'm thinking the next step for me is I should learn how to select the right caps for a recap.

I started in the FAQ's reading Capacitors in Computers, Capacitor ESR, The Bad Capacitor FAQ, and What capacitors should I buy. I also did some searching trying to figure it out and found Cap Datasheet Depot, Capacitor compatibility - noob, and how to order caps from digikey.

I'll be honest, I'm lost. The technical articles capacitors in computers and capacitor ESR went over my head. If I understand everything correctly I want low ESR caps with high ripple. And those need to be spec'd from the recommended brands/series. Physical size is also a factor (diameter only usually).

I went looking for a comparison chart (ex if your cap is this make and model, find a substitute of this brand and model with the same uf and v specs), however that doesn't exist

Everyone refers to pull the data sheets. So when I pull them, what parts am I comparing? ESR and Ripple right?

I guess my questions are:
1 - Do you stick to specific series when recapping? (Like only Nichicon, United Chemicon, or Panasonic - the recommended brands/series here?)
2 - When comparing ESR AND Ripple from old cap to new cap, should the new caps ESR be lower and Ripple be higher than the old? What if you can't find one that both values are better than the older one? Can the values be higher ESR/lower Ripple than the old? [Aren't the recommended brands/series all low ESR or do you have to dig futher...]
3 - Can you just order all of your new caps based on a specific brand/series? (Like all Panasonic FR/FM/FC or all Nichicon HM/HN or all United Chemicon KY/KZE)

Any other advise anyone wants to give, I'm all ears and much appreciative!
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Old 12-26-2013, 04:32 PM   #7
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Quote:
I know the opinion is generally don't touch the main cap (E: CapXon 120uF 420V) however since CapXon is such a bad brand should I go ahead and change it? For a couple of bucks I can't see why not unless you guys think it really isn't needed.
Its up to you, if you want to pay the extra cash, then by all means. Just make sure that the caps are not too wide, so that they can fit together, and that they are not too tall, so that the top of the cans don't touch the chassis.
Quote:
And on the poly, what's the opinion of Elite caps? Again, if it's only a buck I'd rather just change it too and have totally fresh and completely new caps and hopefully not have to give this machine another look for some time.
Garbage... The question is how reliable are their polymer caps... To be honest, the only non-Japanese polymer cap I completely trust is Samxon X-CON series. It has been said that polymer caps must either function or not function and that there is no in-between... But I have seen photos of exploded Taiwanese polymers and have personally had to RMA boards with Taiwanese polymers where the defect could only have been explained by either poor solder joints or faulty caps (*cough*asus/apaq*cough*). Having said that, I am not claiming in anyway that Elite or Capxon polymers are no good, only that I do not *trust* these two companies and the onus is on them to prove their product's longevity.
Quote:
1 - Do you stick to specific series when recapping? (Like only Nichicon, United Chemicon, or Panasonic - the recommended brands/series here?)
Not with a specific series per se, only with specific brands... Stick to UCC, Nichicon, Panasonic, Illinois Capacitor, Vishay, Kemet, etc... I mentioned Vishay and Kemet because I am now noticing that they are distributing Low-ESR series electrolytics somewhat. I sometimes buy KXM series of Illinois Capacitors caps, which are equivalent to UCC KZE.
Quote:
2 - When comparing ESR AND Ripple from old cap to new cap, should the new caps ESR be lower and Ripple be higher than the old? What if you can't find one that both values are better than the older one? Can the values be higher ESR/lower Ripple than the old? [Aren't the recommended brands/series all low ESR or do you have to dig futher...]
Must always be equal to or lower ESR and equal to or higher ripple... When I say 'higher ripple' it's a rating, not a quality - which means to say - the capacitor can tolerate (filter) a DC signal with "higher" or "more" ripple.
Quote:
3 - Can you just order all of your new caps based on a specific brand/series? (Like all Panasonic FR/FM/FC or all Nichicon HM/HN or all United Chemicon KY/KZE)
Yes, you can, but don't. Why? You'll spend a lot more money. Don't use Nichicon HM/HN in power supplies, their ESR is too low. What I do is sort the product by price, and then find the best price/quality ratio. Often a higher quality cap will cost a lot less than a lower quality cap. This is especially important if you are ordering them in bulk.

Always order a few extras if you are so inclined, and in no time you should have a nice little stash for minor repairs in the future...
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Old 12-27-2013, 01:38 AM   #8
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

mockingbird as always I appreciate all your knowledge and patience!

Great tip on the order extra's every time you place an order too, I've been thinking further ahead after I get done with all these PSU's and once I'm done with these comps should I start looking at my 3 dell flatscreens? I see tons of flatscreen problems in the other section of the forums, so now I'm somewhat spooked on that. But to the problems at hand....

I'm trying to wrap my brain around all of this, gone a little crosseyed at times tonight I started looking at the data sheets and trying to sort this out all and realized I'm not 100% sure of one basic question. What is ESR in the data sheet? I'm assuming it's "Impedance".

So before I go further, can you check my work I want to make sure I have a grasp on this before I try to assemble a list cause this is somewhat daunting.

I picked a random cap, from my list, caps B / I (same thing) in my list.
Code:
Cap	Brand	uf	Volt	D MM	H MM	Info on Sleeve:
B	CapXon	1000	10	8	22	GF105C(M)	P1202	VENT
I	CapXon	1000	10	8	22	GF 105C(M)	P1020	VENT
And I pulled it's datasheet from the depot. Capxon [radial] 2011 GF series.pdf

According to the datasheet, that cap's Ripple is 1220 and Impedance is 0.050 (size 8x20).

So then I started searching Digikey. I've noticed alot of the caps you've recommended have been in the Panasonic families, and I used those exclusively via recommendation when I recapped my tivo psu's. They showed up at the top of the list with ripple and were somewhat cheap, so I zero'd in on those for this example.

I looked at the FC and FM series. Datasheets for quick reference: Panasonic [radial thru-hole] FC series.pdf Panasonic [radial thru-hole] FM series.pdf

So for the FC 1000uf 10v cap the datasheet says that cap's Ripple is 995 and Impedance is 0.065 (size 8x20).

And for the FM 1000uf 10v cap the datasheet says that cap's Ripple is 1560 and Impedance is 0.030 (size 8x20).



So am I correct in the following:
First ESR = Impedence

Second, when talking about ESR a.k.a. impedance, lower is closer to zero right? Not higher as in further away from zero with more decimal places? So for example, of the three caps I mentioned above 0.030 is the lowest ESR, 0.050 is the middle, and 0.065 is the highest ESR?

And on to my picks:
The FC cap won't work, ripple is lower and ESR/impedance is higher than the CapXon GF cap.
The FM cap will work, ripple is higher and ESR/impedance is lower than the CapXon GF cap.


Hoping I got a grasp on this! THANKS!
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Old 12-28-2013, 07:40 PM   #9
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Quote:
Originally Posted by bigjess007 View Post
So am I correct in the following:
First ESR = Impedence
Techincally, no. But for all practical purposes, YES.

For those interested:
ESR is not the same as Impedance. However, when capacitors are tested at the factory, this is done with a voltage at a frequency of 100 KHz. At this frequency, ESR is, for all practical purposes, equal to the impedance of the capacitor.
Most devices that require low-ESR capacitors usually work at the 10's and 100's of KHz range (or sometimes even higher). So in those applications, the capacitor's impedance nearly matches the ESR, and you can safely assume ESR = impedance.

I believe PCBONEZ did a technical explanation on this in a post a few years ago, but I don't think I have it bookmarked, so unfortunately I won't be able to link that info here.

Quote:
Originally Posted by bigjess007 View Post
Second, when talking about ESR a.k.a. impedance, lower is closer to zero right? Not higher as in further away from zero with more decimal places? So for example, of the three caps I mentioned above 0.030 is the lowest ESR, 0.050 is the middle, and 0.065 is the highest ESR?
Correct!

Quote:
Originally Posted by bigjess007 View Post
And on to my picks:
The FC cap won't work, ripple is lower and ESR/impedance is higher than the CapXon GF cap.
The FM cap will work, ripple is higher and ESR/impedance is lower than the CapXon GF cap.
Correct again!
I would like to point out, though, that even if you did actually use FC cap here, the device would still likely work. However, the cap will probably be over-stressed, and the repair may not last as long as it would with the properly selected capacitors. Just keep this in mind if you ever run into one of those "in-a-pinch" situations and need to do a temporary repair.

Quote:
Originally Posted by bigjess007 View Post
Hoping I got a grasp on this!
Looks like you do quite well.
Have some fun cappin' now .

Last edited by momaka; 12-28-2013 at 07:46 PM..
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Old 12-30-2013, 02:38 AM   #10
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Momaka, thanks for the answers!

On ESR, I like your answer. As long as for my purposes of comparison it works, I'm rolling with it! I tried to find the post you mentioned from PCBONEZ but I couldn't find it.

So I was busy tonight. Think my eyes have gone crosseyed a few times. Someone mind taking another glance at this and make sure I did this right? My original data is there along with the ESR/Impedance & Ripple values from the datasheets and the new caps are listed to the right (Digikey #, Model #, Size, ESR/Impedance, & Ripple - From datasheets)

Code:
Cap	Brand	uf	Volt	D MM	H MM	Info		ESR	Ripple		Digikey#	Replacement		DxH	ESR	Ripple		

A	CapXon	22	50	5	11	KM105C(M)		60		P14452-ND	EEU-FR1H220		5x11	0.340	250
B	CapXon	1000	10	8	20	GF105C(M)	0.050	1220		P14378-ND	EEU-FR1A102L		8x17	0.041	1240
C	CapXon	10	50	5	11	KM105C(M)		48		565-1598-ND	EKY-500ELL100ME11D	5x11	1.5	100
D	CapXon	100	50	8	11.5	KM105C(M)		200		P14454-ND	EEU-FR1H101		8x11.5	0.061	870
E	CapXon	120	420	18	41	KM105C(M)		630		Whammy!
F	CapXon	47	25	5	11	KM105C(M)		105		P14411-ND	EEU-FR1E470		5x11	0.300	280
G	CapXon	47	25	5	11	KM105C(M)		105		P14411-ND	EEU-FR1E470		5x11	0.300	280
H	CapXon	1800	16	13	20	GF105C(M)	0.026	2380		P14401-ND	EEU-FR1C182L		10x25	0.018	2470
I	CapXon	1000	10	8	20	GF105C(M)	0.050	1220		P14378-ND	EEU-FR1A102L		8x17	0.041	1240
J	CapXon	100	25	6.3	11	GF105C(M)	0.15	410		P14413-ND	EEU-FR1E101		6.3x11	0.130	455				
K	CapXon	1000	10	8	20	GF105C(M)	0.050	1220		P14378-ND	EEU-FR1A102L		8x17	0.041	1240
L	Ltec	1000	10	8	20	LYZ105C(M)	0.040	1300		P12353-ND	EEU-FM1A102		8x20	0.030	1560
M	Ltec	1000	10	8	20	LYZ105C(M)	0.040	1300		P12353-ND	EEU-FM1A102		8x20	0.030	1560
N	CapXon	10	50	5	11	KM105C(M)		48		565-1598-ND	EKY-500ELL100ME11D	5x11	1.5	100
Poly	Elite	1500	6.3	10	12	RP 130		12	5560		P16361-ND	6SEPC1500M		10x13	10	5560
Here's the datasheets for reference:
KM / GF / LYZ / Elite Poly
FM / FR / KY / SEPC Poly

Now on to the questions/problems:
1- I stuck with the Pany FR series alot. Not the cheapest cap (I know contrary to mockingbird's advice) but I liked that the caps had a very long rated life. I actually started with FC/FM's and then noticed the lifetime temp column and actually further eliminated possibilities from the list by selecting 4000 hours and up. This comp will be on all the time, so for a few more bucks now (and all the labor) I figure it's worth it. If it isn't, then I'm all ears on this.
2- The CapXon KM data sheet doesn't have ESR/Impedance listed. Ummmmm? If there's a way to calculate it from info on the data sheets, I sure wasn't understanding it Do you just go by Ripple there or do you have to calculate ESR/Impedance of those caps?
3- Lead spacing....doesn't really matter right? You can always do some interesting bends...? I noticed it half way through selecting caps and honestly didn't want to stop and muddle with it.
4- On the main cap (E), I can't find one in the recommended brands/series. Someone mind taking a look at what's available? I'd rather change it and get rid of the CrapXon unless this really is a leave it alone situation.
5- On the Poly, I couldn't find mockinbird's Samxon X-CON series at either Digikey or Newark14. I found here on BadCaps where the poly's recommended are the Panasonic SEPC's. So I chose the comparable one. This ok?
6- Another question on the poly's, datasheets I believe are listed in mega Ohm's, still want to go closer to zero correct?

I think that's it for this round I'm learning, thanks to y'all! Again, many thanks in advance!
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Old 12-30-2013, 01:27 PM   #11
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Quote:
Originally Posted by bigjess007 View Post
1- I stuck with the Pany FR series alot. Not the cheapest cap (I know contrary to mockingbird's advice) but I liked that the caps had a very long rated life. I actually started with FC/FM's and then noticed the lifetime temp column and actually further eliminated possibilities from the list by selecting 4000 hours and up. This comp will be on all the time, so for a few more bucks now (and all the labor) I figure it's worth it. If it isn't, then I'm all ears on this.
Two things about relying on specs from parametric searches... First is that while they've improved vastly over the years (Especially Digikey, which used to be full of errors), they may not reflect the actual rating in the datasheet. Second is that endurance ratings are often conditional in datasheets (e.g. 4000 hour for 8mm wide and up, only 2000 hours for 6.3mm and less). That's why I would recommend that you get acquainted with the characteristics of each series by memorizing their typical features and deficiencies from datasheets. You should aim to be informed at least of the three tiers of caps. First is General Purpose, which I always ignore in my searches, and then there is the middle tier and the upper tier.
Quote:
2- The CapXon KM data sheet doesn't have ESR/Impedance listed. Ummmmm? If there's a way to calculate it from info on the data sheets, I sure wasn't understanding it Do you just go by Ripple there or do you have to calculate ESR/Impedance of those caps?
That's because it's a general purpose cap... Never replace GP caps with new GP caps. You should isntead familiarize yourself with middle tier caps... These are almost always equally priced to and often even cost less than GP equivalents... To give you an example, Nichicon PW, Panasonic FC, Rubycon YXG, etc...
Quote:
3- Lead spacing....doesn't really matter right? You can always do some interesting bends...? I noticed it half way through selecting caps and honestly didn't want to stop and muddle with it.
Except in rare instances, where they may actually be two different caps with the same dimensions but different lead spacing, the overwhelming majority of lead spacing differences that you see in your parametric search is by a physical bend in the leads, either for narrowing or widening. Don't worry about it.
Quote:
4- On the main cap (E), I can't find one in the recommended brands/series. Someone mind taking a look at what's available? I'd rather change it and get rid of the CrapXon unless this really is a leave it alone situation.
Here you go, if you really wanna spend the extra $5.
Quote:
5- On the Poly, I couldn't find mockinbird's Samxon X-CON series at either Digikey or Newark14. I found here on BadCaps where the poly's recommended are the Panasonic SEPC's. So I chose the comparable one. This ok?
Yes. The one you chose matches just fine.
Quote:
6- Another question on the poly's, datasheets I believe are listed in mega Ohm's, still want to go closer to zero correct?
You mean Milliohms... So that would be 0.010. Less would be 0.009, 0.008 and so on. Not to be confused with 0.10 which is 100 milliohms and 0.90 or 0.80... Capacitors over 0.60 tend to fall into the GP category, or at least they do for our purposes... Capacitors under 0.020 fall into the Ultra Low-ESR category...
Quote:
I think that's it for this round I'm learning, thanks to y'all! Again, many thanks in advance!
"A person who is too shy to ask questions will never learn, and a teacher who is too strict cannot teach . . . and in a place where there are no men, strive to be a man."
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Old 12-30-2013, 01:55 PM   #12
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

mockingbird, thanks! And as you guessed it, I got more questions There is alot to learn!

Quote:
Two things about relying on specs from parametric searches... First is that while they've improved vastly over the years (Especially Digikey, which used to be full of errors), they may not reflect the actual rating in the datasheet. Second is that endurance ratings are often conditional in datasheets (e.g. 4000 hour for 8mm wide and up, only 2000 hours for 6.3mm and less). That's why I would recommend that you get acquainted with the characteristics of each series by memorizing their typical features and deficiencies from datasheets. You should aim to be informed at least of the three tiers of caps. First is General Purpose, which I always ignore in my searches, and then there is the middle tier and the upper tier.
I found that part now on page 1 in the datasheets under endurance. But I'm not sure what you mean about "get acquainted with the characteristics of each series by memorizing their typical features and deficiencies from datasheets. You should aim to be informed at least of the three tiers of caps." Do you mean the endurance? Or other specifics of the cap. And aren't all the caps I'm looking at (BadCaps recommended series) middle/upper tier cap's? If not how do you distinguish which cap a tier is in?

Quote:
That's because it's a general purpose cap... Never replace GP caps with new GP caps. You should isntead familiarize yourself with middle tier caps... These are almost always equally priced to and often even cost less than GP equivalents... To give you an example, Nichicon PW, Panasonic FC, Rubycon YXG, etc..
The FR and FM's I choose aren't GP's right? I'm guessing that both FR/FM is upper tier and FC is middle (based on both endurance ratings and where they are in the list of highest to lowest ESR). But that's based on my assumption about endurance & ESR = tier rating.

Are my choices in general ok? I think I just choose best instead of better.

Quote:
Except in rare instances, where they may actually be two different caps with the same dimensions but different lead spacing, the overwhelming majority of lead spacing differences that you see in your parametric search is by a physical bend in the leads, either for narrowing or widening. Don't worry about it.
Less things to worry about is good news to me!

Quote:
Here you go, if you really wanna spend the extra $5.
I'll change it. TY for that, it wasn't in the recommended list at all. Might as well vs the time it would take to pull the PSU out and get a new cap in the mail and that ofcourse doesn't include the downtime. Expensive little bugger

Quote:
You mean Milliohms... So that would be 0.010. Less would be 0.009, 0.008 and so on. Not to be confused with 0.10 which is 100 milliohms and 0.90 or 0.80... Capacitors over 0.60 tend to fall into the GP category, or at least they do for our purposes... Capacitors under 0.020 fall into the Ultra Low-ESR category...
All it says on the Panasonic sheet is (m Ohm) and on the Elite sheet (m Ω max) so I guessed it was mega. And then it only gave the values as 10 for the Pany and 12 for the elite. So I figured closest to zero was still the goal. Am I correct in that those caps are indeed 0.010 and 0.012?


As usual, thanks again!!!!!!!
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Old 12-30-2013, 04:15 PM   #13
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

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mockingbird, thanks! And as you guessed it, I got more questions There is alot to learn!
No problem! Glad to help.
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I found that part now on page 1 in the datasheets under endurance. But I'm not sure what you mean about "get acquainted with the characteristics of each series by memorizing their typical features and deficiencies from datasheets. You should aim to be informed at least of the three tiers of caps." Do you mean the endurance? Or other specifics of the cap. And aren't all the caps I'm looking at (BadCaps recommended series) middle/upper tier cap's? If not how do you distinguish which cap a tier is in?
No. What I meant was get acquainted with average ESR and ripple ratings for common series... For instance, off hand I can tell you that 12.5mm Panasonic FR caps tend to have a 20 milliohn impedance or less... Endurance ratings are arbitrary and don't always have bearings in the real-world...
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The FR and FM's I choose aren't GP's right? I'm guessing that both FR/FM is upper tier and FC is middle (based on both endurance ratings and where they are in the list of highest to lowest ESR). But that's based on my assumption about endurance & ESR = tier rating.
You got it... I would say FM and FR are middle to high-end tier, depending on the specific cap... That means to say, there can even be caps within the so-called middle-tier which are equal to equivalent caps from higher tier series... The only time I see the need for GP caps are when there's no stock of a higher-tier cap, and when that happens I try to get a 105C rated cap. This is only sometimes the case with the small-value 5mm or less caps. Digikey might stock a certain series that neither Mouser nor Newark carry, and that is when I stock up.

A recent example for me was a 5mm 6.3V 220uF cap for a Foxconn motherboard... I had to get it from Digikey because only they had that oddball cap in a high quality series (I think it was Rubycon ZLJ IIRC).
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Are my choices in general ok? I think I just choose best instead of better.
A preliminary check says yes...
Quote:
I'll change it. TY for that, it wasn't in the recommended list at all. Might as well vs the time it would take to pull the PSU out and get a new cap in the mail and that ofcourse doesn't include the downtime. Expensive little bugger
Yea... no one wrote any doctorates about big caps so far because generally speaking, there have only been two kinds in the past. 85C rated and 105C rated... Now they're starting to manufacture 5-10,000 hour big caps because the higher endurance is actually required for HO fluorescent ballasts or LED ballasts where things get really toasty inside.
Quote:
All it says on the Panasonic sheet is (m Ohm) and on the Elite sheet (m Ω max) so I guessed it was mega. And then it only gave the values as 10 for the Pany and 12 for the elite. So I figured closest to zero was still the goal. Am I correct in that those caps are indeed 0.010 and 0.012?
Yup. Good luck, please post the results.
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Old 12-30-2013, 04:19 PM   #14
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

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I actually started with FC/FM's and then noticed the lifetime temp column and actually further eliminated possibilities from the list by selecting 4000 hours and up. This comp will be on all the time, so for a few more bucks now (and all the labor) I figure it's worth it.
It's worth it if the caps will be ran near their maximum specs/tolerances. Otherwise, you have a little bit more freedome to choose other caps.

Just to clear things up...
Lifetime is NOT equal to the number of hours the cap will work and then simply quite working.
Rather, lifetime is usually the minimum guaranteed time that the cap will work under full stress and still meet all of its parameters on the data sheet. For most caps, this is at their rated temperature, voltage, and ripple current ratings. Lowering this stress means the cap will live longer.

The lifetime of a capacitor is normally directly related to its temperature. For every 10C that the temperature on the capacitor drops, the lifetime more or less doubles. So say you have a capacitor rated for 2000 hours at 105C (a typical ultra-low ESR cap). If the cap runs at 95C in the device that it is installed, and the voltage and ripple current are at maximum allowed, then the lifetime of this capacitor will be 4000 hours. If the temperature was to drop another 10C (so 85C), the lifetime doubles again to 8000 hours, and so on.

So for every 10C drop in temperature, the lifetime of the capacitor doubles.
With that said, you don't really need to get capacitors rated for the highest lifeitme. Sure, it's a good thing. But in most cases, a high quality Japanese capacitor will outlast the useful life of the device that it is installed in as long as it's not ran near its maximum.

Example: 1 year has 365 x 24 hours.... or 8769 hours.
Most cheap Chinese and Taiwanesse capacitors are rated for 2000 hours, yet sometimes even they last for years in equipment. This is simply because they aren't stressed near their maximum. And keep in mind the majority of Chinese and Taiwanesse capacitors are quite more inferior when compared to Japanese capacitors.

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Originally Posted by bigjess007 View Post
3- Lead spacing....doesn't really matter right? You can always do some interesting bends...?
Yes.
But it's easier to just "drop-in" the cap and not have to do any bending.
Generally speaking, though, whenever you match the capacitor diameter to the diameter of the spot on the circuit board, the lead spacing will match. In other words, if the circuit board is marked for a 10 mm dia. cap and you buy a 10 mm dia. replacement cap, it will almost always fit in just fine (save for some crappy Chinese circuit boards).

Because of this, you don't really have to do anything with the lead spacing filters on digikey or mouser. Just match the cap diamter to the spot on the PCB and you're good to go. Some of the more standard sizes are 12.5 mm, 10 mm, 8 mm, 6.3 mm, and 5 mm.
*Note: 12.5 mm and 10 mm caps usually have the same lead spacing.

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Originally Posted by bigjess007 View Post
If not how do you distinguish which cap a tier is in?
Usually, you pick it up when you start comparing a lot of data sheets.

In general, though, this is the tier list of Japanese capacitors I can tell you from top of my head...

Entry level low ESR: Panasonic FC, Nichicon PW PS PM PV, United Chemicon LXY LXV LXZ, Rubycon YXA(?)

low ESR: Panasonic HFQ (now obsolete, I believe) and possibly FK, Nichicon HE, United Chemicon KY, Rubycon YXG

between above and below entries: Panasonic FK

very low ESR: Nichicon HC and HD, United Chemicon KZE, Rubycon ZL

lower very low ESR: Panasonic FR and FM, Rubycon ZLG ZLJ and ZLK,

ultra-low ESR (usually motherboard CPU-grade): Panasonic FL, Nichicon HM HN and HZ, United Chemicon KZG and KZJ (these are known to go bad, though, so replace on sight), Rubycon MBZ and MCZ (and MFZ if you ever pull some from an Xbox 360)

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Originally Posted by bigjess007 View Post
But that's based on my assumption about endurance & ESR = tier rating.
The "tier rating" is usually based on the ESR and ripple current. (I put it in quotes, because there is no such thing in data sheets as a tier rating. It's more of a tool for us recappers to keep in mind when sourcing caps.)

Quote:
Originally Posted by bigjess007
And then it only gave the values as 10 for the Pany and 12 for the elite. So I figured closest to zero was still the goal. Am I correct in that those caps are indeed 0.010 and 0.012?
Yes.
0.010 Ohms and 0.012 Ohms (or 10 and 12 milliOhms). Take your pick .

Last edited by momaka; 12-30-2013 at 04:34 PM..
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Old 01-07-2014, 01:43 AM   #15
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

So much good info, where to start! First ofcourse, many thanks mockingbird and momaka. I think i'm getting this. Sorry I'm just now getting back here, been a hectic week.

I understand what your saying now on the cap "tier's". You want to stay in the same "tier levels" as what your replacing. You can go to the high end, but your going to pay more and it may not be necessary. I'll confess though, I don't know that I'll ever get ESR ratings to memory But I did download and am slowly going to start printing all the middle and high end series datasheets. I seem to be a Panny lover, those are already printed I am making a "cheat sheet" though, got to keep organized what I've already learned (love that tier ranking of the popular caps btw, a helpful place on where to start when comparing!!!).

The info on the ratings is good to know too. I knew the colder electronics ran the better and lasted longer, but the way you broke it down makes sense especially in regards to those hour ratings. Really interesting insight. I did that yearly hours calc myself when I was picking the caps and thought man, they really aren't rated to last long. Well that's before I understood that rating is based on if they are at max use and temp, keep em cool and you can get a decade, probably more. And if I'm doing my math right, in your example of a 2000 hour cap, running at a average temp of 25C gets a lifetime of 256000 hours or ~29 years. Now that's more like it! (My math was: 105-95-85-75-65-55-45-35-25 is 8 10 drops, so 2000-4000-8000-16000-32000-64000-128000-256000) Very interesting stuff.

Great info on the lead spacing too. I ordered same size (diameter) caps and they all fit. One less thing to have to filter through. The little ones had to be bent, that I expected.

On those polymer's, ya, that flew over my head when I looked at it (makes sense now that you explained it). The data sheets just all need to be in 0.XXXX format lol I can compare that haha!
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Old 01-07-2014, 01:50 AM   #16
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

So with the holidays, digikey having an "unexpected internal delay", and the weather; my order that I placed last Monday morning arrived Saturday. BAH! I understand the need to building a stash. The recap went smooth, well sort of lol. I got all the old ones out without many issue (I despise that damn glue stuff they use to hold em on). I'm loving this power supply in that the fan just unplugs from the board, instead of having to either solder it off or carefully keep it attached. The board has more room too, everything isn't crammed together. Much better than those gx620 psu's (boy do I have a story on that, it'll be in the other thread soon).

So I get them all removed and didn't mess up any trace's. My technique must be improving some (found myself adding solder and then taking it all off to desolder, way good tip). Got that big boy soldered in too.

Go to put it back together and test and well, it won't fit. Hmmm, whats the problem? Anyone want to take a guess?

Ya, the big boy is too tall! dulp! I thought it would sit down past the fan. It catches the edge of it. UGH! So luckily I didn't destroy the old one when I removed it. So I fluxed the hell out of it's leads and jammed it back in. Closed it back up and tested. So far so good. One thing I've noticed that's weird is that the comp is intermittently freezing when you try to do something. It's late and I'm tired, so it might just be me, will have to investigate in the morning.

Somewhere on that big boy I screwed up. When I posted my data table, I had corrected some of my measurements based on the datasheets as I was usually 1MM +/-. Well I don't know what happened with the big one as the data sheet says it's 41MM high, but my caliper's say it's 35MM. Guess I figured I was way off and just took the datasheet's specs. Here's the really weird thing, I can't find where CrapXon made that 120uf 420v cap in a 18 x 35 configuration. But if you google search it, there are results saying be sure to change the big 18x35 120uf 420v CapXon cap as it will fail. And I double checked it with my caliper's, definately only 35MM high. Barely fits under the fan.

So anyone got a recommendation now on a replacment for that d**n cap? I've checked mouser, newark 14, and digikey, only digikey has one cap that meets the uf/v specs and is 18x35 and is a radial with leads (they've got others but they are snap in's). For giggles I searched ebay, quite a few on there that say they meet my needs, but all are from china. So I'm guessing they're counterfeit.

Other than the big boy issues, all went well. Sorry I didn't get any after pictures, the big cap problem threw me off. I'm tired and needed to get the comp back up and runnning. I quickly desoldered the new big cap, soldered the old big cap back in, closed it up, and put the PSU back in and got the comp running again to test and then realized I didn't take any after pics.

And thanks again!!
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Old 01-07-2014, 10:30 PM   #17
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

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So anyone got a recommendation now on a replacment for that d**n cap? I've checked mouser, newark 14, and digikey, only digikey has one cap that meets the uf/v specs and is 18x35 and is a radial with leads (they've got others but they are snap in's).
Try this guy, higher voltage and ripple:

http://www.digikey.com/product-detai...377-ND/3134333


Quote:
For giggles I searched ebay, quite a few on there that say they meet my needs, but all are from china. So I'm guessing they're counterfeit.
Not necessarily, but very probably. There are lots of real caps on Ebay, but for every real one there's probably a dozen counterfeits, and the counterfeits are getting better and better.
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Old 01-08-2014, 12:38 AM   #18
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

Nice! Glad you got your computer working.
Yeah, good thing you didn't get one of those crammed form-factor PSUs. I've had to do an HP DC5000/D530 PSU once, and it wasn't much fun. I guess similar experience to what you had with the GX620 .

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But if you google search it, there are results saying be sure to change the big 18x35 120uf 420v CapXon cap as it will fail.
Yes. While high-voltage capacitors like that don't usually fail, CapXon is one of the few select brands that does have their high voltage caps fail - they are that crappy! I think there are even a few documented cases here on Badcaps of CapXon primary caps failing.

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Originally Posted by bigjess007 View Post
So anyone got a recommendation now on a replacment for that d**n cap? I've checked mouser, newark 14, and digikey, only digikey has one cap that meets the uf/v specs and is 18x35 and is a radial with leads (they've got others but they are snap in's).
This is the only thing I could find on Mouser. It's pretty much equivalent to what you found, though. So it's just whatever place you prefer to get the caps from.
http://www.mouser.com/ProductDetail/...aK2OmBt7TgQ%3d

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Originally Posted by bigjess007 View Post
For giggles I searched ebay, quite a few on there that say they meet my needs, but all are from china. So I'm guessing they're counterfeit.
If it's from China, really high chance that it is. I don't waste my time with that. Fleabay is good for other cheap stuff where quality doesn't matter too much... like my type-K temperature thermometer. For $5 shipped from China, it's a great buy.

Last edited by momaka; 01-08-2014 at 12:42 AM..
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Old 10-15-2019, 04:12 PM   #19
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Default Re: Dell Optiplex 780 SFF and AC235AS-00 PSU

The C4 (120uF/420V CapXon KM) cap in Acbel AC235AS-00 PSU is known to fail, causing Q3 (SPP11N60C3) to short and F301 (F6.3AH/250V) to burn.
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