VOGONS


First post, by Almoststew1990

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Hi everyone

I have this board which seems to be quite nice other than a few caps. I am looking to have a go at replacing some and this will be the first time I try it. I will have a practice on a busted graphics card first though.

Anyway, can anyone identify what the specifications of the three dark blue caps that are bulging, and where I could get replacements from hopefully in the UK?

CFJkenhh.jpg
VIMVecph.jpg
If you can't see that they're dark blue and are branded with "GSC" [LE] 105c T29D" one of them is T29E.

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Reply 1 of 49, by PCBONEZ

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CONGRATS!
You scored a set of what may be the worst caps ever made!
GSC were so bad (and so well known for it) the company changed their name TWICE before they folded.
ALL of those need to go. Not just the ones that are bloated. With this particular brand only about 1/3 of the bad ones will bloat.

The first step is to make a cap map. This is not trivial for a couple of reasons.
1- If you have some caps removed and get interrupted by life when you come back to it you probably aren't going to remember which cap goes where.
2- Sometimes there are uncorrected errors in the board markings (silk screen) that show the wrong polarity.
What I usually do is either use a photo or a pic from the mobo manual and resize it to fit well on an 8.5x11 sheet of paper. (And of course print it.)
Next is to draw a little circle for each cap.
Next is to mark the polarity in the circles. I usually draw a line from the center to the negative side - but that's a style thing.
Next start documenting what all the caps are by Series, Diameter (in mm), uF, Volts, and if it's an odd size Lead-Space.
-- It's usually easier (especially if you have have a bunch that are the same - and you will) to put a number on each on the drawing and use that number for a line item in a list off to the side.

You stated one Series is LE. I'm guessing the other is RE?
.

Last edited by PCBONEZ on 2018-04-12, 22:45. Edited 1 time in total.

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Reply 2 of 49, by CkRtech

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Almoststew1990 wrote:

I am looking to have a go at replacing some

I'd replace all of them.

and this will be the first time I try it. I will have a practice on a busted graphics card first though.

Be aware that desoldering caps from a mobo means you have to deal with a multilayer PCB - several layers, really. The ground plane might cause you a bit of trouble when it comes to desoldering them. You may find that some of them are stubborn on the minus side (connected to ground) but easy on the plus side.

I could elaborate a bit more, but it sounds like this might be your first desoldering experience... ever? It isn't really a beginner-friendly operation.

I am not discouraging you from recapping it - I am just saying that it can require some solid techniques and heat on/heat off/heat on/heat off + patience if you don't have a way to preheat the board and/or don't have the best tools for desoldering.

PCBONEZ has a step up on guiding you toward replacements. Generally the caps near the CPU are low ESR, and the ones further away (near expansion slots, etc) are general purpose filter caps. Once you make a cap map, you can start to get a beat on how many replacements you need of each type.

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Reply 3 of 49, by Almoststew1990

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Thanks for the tips - a cap map sounds like a sensible idea. I'll have a look at the guide as it sounds like it isn't going to be a case of warming up the existing solder and pulling them out and then threading the new ones in and setting them with new solder. it is my second time using a soldering iron in my life 😒 I'm borrowing my dad's. Maybe I'll give it a few goes on my broken MX GPU first...

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AMD DX2-80 | 16MB RAM | STB LIghtspeed 128 | AWE32 CT3910
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Reply 4 of 49, by PCBONEZ

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CkRtech wrote:

Generally the caps near the CPU are low ESR, and the ones further away (near expansion slots, etc) are general purpose filter caps.

I'm sorry that is just not true.
I never tried to figure exactly when the transitions were but at least by the mid/late P-III era all the caps (over 6 mm) on motherboards were low ESR.
That said, you could certainly find a cheaped-down model or brand where that wasn't true but it was not common by then.
Going way back to the 486 era it would be unlikely to see anything except GP caps anywhere on the board.

There are tiers of Low ESR.
Some companies use terms like "Low ESR", "Very Low ESR", "Ultra Low ESR" (I've even seen "Super" mixed in) to distinguish the tiers in their own product lines, but there is no Industry Standard defining or requiring those terms.
So one companies "Ultra Low ESR" might be equivalent to another's "Low ESR".

Your general idea that the caps near the CPU usually have lower ESR than what I call the "field caps" is absolutely true...
... but the field caps are still classified as Low ESR.
Gotta watch that though because caps for/near the RAM (and that bugger near the AGP slot) often had ESR on a par with the CPU (VRM) caps rather than the field caps. At first glance they appear to be field caps but they aren't.
.

Last edited by PCBONEZ on 2018-04-12, 22:31. Edited 4 times in total.

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Reply 5 of 49, by PCBONEZ

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Almoststew1990 wrote:

Thanks for the tips - a cap map sounds like a sensible idea. I'll have a look at the guide as it sounds like it isn't going to be a case of warming up the existing solder and pulling them out and then threading the new ones in and setting them with new solder. it is my second time using a soldering iron in my life 😒 I'm borrowing my dad's. Maybe I'll give it a few goes on my broken MX GPU first...

You can use a plain traditional type soldering iron but you need one that is between 60 and 80 watts.
Anything less will (or can) give you two problems.
1- You will have trouble getting enough heat to the middle of the board for the cap lead to release all the way through the hole.
2- In replacing them too small an iron will cause you to have to heat the leads for a longer time - which is not good for the new cap.

Someone with MUCHO soldering experience can get by with a 40 watt but few prefer it.

I'm at the end of a long day so I'll get to the shopping list later.

I should have mentioned earlier that the side with the stripe is the negative side.

Practicing on something you don't care about is a grand idea.
.

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Reply 6 of 49, by dionb

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PCBONEZ wrote:
CONGRATS! [...] […]
Show full quote

CONGRATS!
[...]

The first step is to make a cap map. This is not trivial for a couple of reasons.
[...]
.

Alternative, which I'd recommend anyway first time: replace them them one by one, starting with the most accessible.

That way you never have more than one cap off the board and you won't forget polarity (at least, if you're aware of it, which is recommended 😉 )

Also, by the time you get to the tricky ones crammed in between slots and MOSFETs you've been through the whole operation several times.

Reply 7 of 49, by CkRtech

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PCBONEZ wrote:
CkRtech wrote:

Generally the caps near the CPU are low ESR, and the ones further away (near expansion slots, etc) are general purpose filter caps.

I'm sorry that is just not true.
I never tried to figure exactly when the transitions were but at least by the mid/late P-III era all the caps (over 6 mm) on motherboards were low ESR.

Ha. Well... never recapped any late P3 or higher era boards. Heck - now they all use polymers or whatever else they like to use. I just know that the recaps I have done (440 BX or earlier) didn't need much, and you are more likely to have issues if you don't nail low ESR for the caps near the CPU

How low of an ESR do you really need for some secondary power filtering near an expansion slot?

Ideally you find the datasheet for the previous caps (if available) and go from there. Even for what I call "general purpose" - I still get a pretty good line from a good brand, and they tend to have tighter values overall.

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Reply 8 of 49, by PCBONEZ

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dionb wrote:
PCBONEZ wrote:
CONGRATS! [...] […]
Show full quote

CONGRATS!
[...]

The first step is to make a cap map. This is not trivial for a couple of reasons.
[...]
.

Alternative, which I'd recommend anyway first time: replace them them one by one, starting with the most accessible.

That way you never have more than one cap off the board and you won't forget polarity (at least, if you're aware of it, which is recommended 😉 )

That's not a bad idea especially when you're learning and don't have a mountain of boards needing caps in your in-box (so to speak.)
You still need to do the cap-map to guard against errors in the silk screen leading to installing a cap backwards.

Also it's very common to find boards that were marked and drilled for caps that never got installed in the final design.
In other words you can take out one cap and have multiple empty positions on the board.
.

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Reply 9 of 49, by PCBONEZ

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@CkRtech
I'm going to answer your questions in detail such that the newest of cap newbies will get it. (will help folks later on)
I'm also going to try and preemptively answer the follow on questions that usually come up.
To do that I might need to bust it up into multiple posts.
.
Insofar and datasheets, I was a 'professional recapper' for a little over a decade and I have datasheets on file for hundreds of brands and/or series that no longer exist online. For the brand in question (which I'll call GSC-Evercon-Sacon) I have most of their series on file.
.

GRUMPY OLD FART - On Hiatus, sort'a
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Reply 10 of 49, by eisapc

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Considering the time you spend in recapping I allways go for low ESR 105°C caps, usually ones from Panasonic. The difference in price is not worth the risk having to recap a second time. 80W is a good recommendation for solderworks on multi layer PCBs, but a temperature controlled soldering station is recommended as well. Otherwise you may damage the board using too much heat. A desoldering pump is recomended as well, to free the tiny holes from excessive solder before inserting the new caps. I prefer adding some leaded solder during desoldering due to the lower melting point against lead free solder.

Reply 11 of 49, by PCBONEZ

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Some terms and a bit of history..

First there are more that two types of low ESR caps used in PCs.
Aluminum Electrolytic, Solid Polymer, Hybrid Polymer and Tantalum.

Hybrid and Solid Poly caps performance longevity and all that are so similar they are considered the same thing even though structurally they aren't.
Few people outside the cap manufacturers themselves even realize there is a difference.
So when you see "Poly" or "Solid" or "Solid Polymer" it usually means both or either polymer type.

Tantalum were experimented with by multiple manufacturers and ultimately rejected for most PC applications because they don't tolerate ripple very well and tend to die young. They did (and might still) see some use in laptops because they are small and the nature of laptop power bricks is such that they aren't exposed to more ripple than they can handle. There are 'wet-tantalium' and 'dry-tantalium'. Wet-tantalium fell out of favor in IT equipment quickly because their electrolyte is highly acidic and will eat just about anything it leaks on to. If you have a leaker gloves are a good idea.

Aluminum Electrolytic ["Lytics"] (the most commonly used type before 2010-ish) have wet electrolyte on both plates.
Unfortunately many of the best choices for replacements are no longer manufactured.
Early on these were the only practical choice. Poly had limited uF capability and were very expensive.
Lytics could simultaneously get the ESR low and pack enough uF into a small enough package to avoid needlessly wasting space.
They are also resistant to damage from ripple.

Solid Polymer. Have polymer electrolyte on both plates. (Basically a kind of soft non-hardening plastic.)
They were invented by Sanyo who by way of patent rights was the exclusive producer until some time in the early 2000's.
Sanyo's trade name for their solid polymer caps is OSCON.
Initially, due to tech limitations, OSCON were only available in small sizes (like 330uF or less) and were physically large for their uF value.
In the 1990's a single 330uF OSCON could cost you $30 so they were not common.
Eventually the tech limitations were overcome and and patent rights ran out.
Now Solid Poly caps are made to much larger uF values but the larger ones are still more expensive than other options and actual OSCON are more expensive than other brands.

Hybrid Polymer. [aka Functional Polymer] Have polymer electrolyte on one plate and wet electrolyte on the other.
Invented by Fujitsu to compete against OSCON. - Functional Polymer were cheaper to produce.
Fujitu's trade names for the product were "Functional Polymer" and/or "FP-Cap" or "FPCAP".
Fujitsu only retained exclusive rights for a short time before licensing the right to produce to other companies.
This busted Sanyo's monopoly and is the main reason polymers started getting cheaper in the early 2000's.
Just few years ago Fujitsu sold the subsidiary responsible for FP-Caps to Nichicon.

At this point Poly's are only slightly more expensive than Lytics in most sizes and in some cases (high production sizes) can even be cheaper.
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Reply 12 of 49, by PCBONEZ

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eisapc wrote:

Considering the time you spend in recapping I allways go for low ESR 105°C caps, usually ones from Panasonic. The difference in price is not worth the risk having to recap a second time. 80W is a good recommendation for solderworks on multi layer PCBs, but a temperature controlled soldering station is recommended as well. Otherwise you may damage the board using too much heat. A desoldering pump is recomended as well, to free the tiny holes from excessive solder before inserting the new caps. I prefer adding some leaded solder during desoldering due to the lower melting point against lead free solder.

Clearly you know what you're doing.
Absolutely want to use 105°C caps and it makes no sense to buy GP when the cost difference to low ESR is usually nill.
Panasonic FJ (ESR suitable for VRM use) are one of my favorite series because they come in some physical sizes that are tough to find.
FC and FM have been around for eons and have uses in PSU, for field caps, or even VRM on some pre P-III boards. (But they tend to be big.)
FR is a relatively new series and seems to be intended as a downsized (physically smaller) replacement for FM.

While the fancier equipment is nice and does make things easier someone on a low budget or that only replaces caps occasionally can get the job done just fine without it.
Doesn't make sense to invest in that stuff if you are only going to do one recap or one once in a while.
I generally tailor my guidance toward folks that have minimal basic equipment and can't afford or don't want the fancy gear.
.

GRUMPY OLD FART - On Hiatus, sort'a
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Reply 13 of 49, by SpectriaForce

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Honestly, if you’re not experienced with soldering on this recent hardware and you only have a run of the mill soldering iron, then it’s better to hire a professional. You’re going to run into a LOT of frustration otherwise and the time you spend on it will not be worth it. I know because I’ve tried 😐

Reply 14 of 49, by PCBONEZ

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@SpectriaForce
Some people have the knack. Others don't. (That's not meant to be derogatory. There are things I suck at.)

That's another reason not to buy the fancy equipment for the first project.
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Reply 15 of 49, by gdjacobs

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eisapc wrote:

Considering the time you spend in recapping I allways go for low ESR 105°C caps, usually ones from Panasonic. The difference in price is not worth the risk having to recap a second time. 80W is a good recommendation for solderworks on multi layer PCBs, but a temperature controlled soldering station is recommended as well. Otherwise you may damage the board using too much heat. A desoldering pump is recomended as well, to free the tiny holes from excessive solder before inserting the new caps. I prefer adding some leaded solder during desoldering due to the lower melting point against lead free solder.

A desoldering iron is nice, certainly, but braid, a manual sucker, and a small selection of stainless picks and needles for cleaning through-holes should be sufficient.

All hail the Great Capacitor Brand Finder

Reply 16 of 49, by PCBONEZ

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CkRtech wrote:

How low of an ESR do you really need for some secondary power filtering near an expansion slot?

The short and ultimate answer is enough to keep the ripple below the max allowed by the ATX spec. (After you install add-in cards.)
But I don't think that's going to help people much.........

The long answer is that it is vintage and design dependent. Also slot use dependent.

[Design and slot factors]
If the expansion slot is for a video card (AGP, 1st PCI-E) there is usually 1 (sometimes 2) cap is are VRM grade.
[Video cards usually have some on-board step-down regulators. This cap filters the input to those regulators.]
It's a similar situation near the RAM slots but there are usually more than 1 or 2.
I've also seen consumer boards that don't have any VRM grade caps near the RAM.
--- Why?/How?
ESR in parallel works just like resistance in parallel. (Same equations.)
Thus designs can use many lesser grade caps or just a few high grade caps to achieve the same total circuit ESR.
One board might have 5 field caps on a rail and another 12 on the same rail - but their total ESR can be the same.

[Vintage factor]
I have trouble explaining this well without writing a book (or creating more questions than I answer) but I'll give it a shot.
This has to do with signaling voltages which have been getting smaller and smaller.
Old stuff used 5v signaling for just about everything. Now we have signaling voltages that are less than 1v.
There are signaling voltages all over a board that no one thinks about. Chipsets usually have several.
(Numbers off the top of my head here.)
For 5v signaling the point the logic trips to a '1' would be something like 4.5v-5.0v [ 4.75 +/- 0.25 V ]
For 0.8v signaling (as used in AGP 8x) it would be something like 0.6v-0.8v [ 0.7 +/- 0.1 V.]
If you had 120 mV (0.12 V) ripple (max IAW the ATX spec) it would be unlikely to cause a logic error on the 5v signal but easily could on the 0.8v.

===
There is a reason they scatter the field caps around instead of lumping them all off to the side somewhere.
One of the design concerns is that parasitic elements in the board will create an antenna like effect where ripple (which is usually around 100kHz) will travel to the end of a trace and then bounce back. (Parasitic elements = inductance and resistance in traces, capacitance between traces.)
They get around that problem by 'draining' the ripple off at multiple distant points.
The spaces between slots is a convenient place to put some of these drains.

===
Regardless of vintage ripple causes heat in traces and components that serves no useful purpose.
.

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Reply 17 of 49, by PCBONEZ

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Almoststew1990 wrote:

where I could get replacements from hopefully in the UK?

These folks are popular. I dunno how their stock is for caps these days.
https://uk.rs-online.com/web/
http://uk.farnell.com/
Badcaps.net will ship there but IMHO he's a bit pricey so a last resort.

Almoststew1990 wrote:

"GSC" [LE] 105c T29D" one of them is T29E.

Just FYI. The T29D and T29E are only the date codes.
Not useful for IDing replacements.

The info that is needed is
Make
Series
uF
Volts
Diameter
Length
.. and maybe ..
The standard lead-spaces are 5mm for 10 & 12.5mm caps and 3.5mm for 8mm caps.
If they are not standard it should be noted.
.

GRUMPY OLD FART - On Hiatus, sort'a
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Reply 18 of 49, by CkRtech

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PCBONEZ wrote:
CkRtech wrote:

How low of an ESR do you really need for some secondary power filtering near an expansion slot?

The short and ultimate answer is enough to keep the ripple below the max allowed by the ATX spec. (After you install add-in cards.)

Hmm. My question was actually rhetorical. Haha. But it is good to have a detailed answer about it.

The most recent cap job I did on P3 had "general usage" caps for everything but the CPU. Of course from one line of caps to another, that term is rather relative...

The replacements I used were much higher quality and low impedance, but not from a series intended to be low ESR. (Panasonic KA and Nichicon UPW/UHE)

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Reply 19 of 49, by SpectriaForce

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PCBONEZ wrote:
@SpectriaForce Some people have the knack. Others don't. (That's not meant to be derogatory. There are things I suck at.) […]
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@SpectriaForce
Some people have the knack. Others don't. (That's not meant to be derogatory. There are things I suck at.)

That's another reason not to buy the fancy equipment for the first project.
.

I have soldered on old tube radio's, tv's and really old home computers in the past. I have just enough experience and the right equipment to do that. I have some idea of what I do and own a pretty good Weller soldering station. That having said, these more recent motherboards were soldered in a factory with a computer and temperature controlled precision soldering machine using lead free solder (various methods exist). Maybe some of you can solder on a motherboard like this, but it probably takes years of experience and advanced tools. There's a good chance you get cold solder joints if you just try something.

Also take a look over here: https://www.eevblog.com/forum/beginners/mothe … er-not-melting/

And here: https://www.google.nl/search?q=preheat+mother … 0&bih=882&dpr=1