How to exchange caps - tutorial

A little photo guide about how I do it 🙂 Dedicated to Datsun 1600 - thank you, dear friend.

You will need a classic transformer soldering iron, no less that 75W. I use this oldie one for 26 years:

The prolonging of the soldering iron tip is necessary - additional resistance stop overheating the soldering tip too much.

Some resin is need too:

And a little bit of tin:

And tin suction tool:

…and of course replacement caps and something with bad caps. In this case I choose very simple recap of Jaton GF2MX400 card. Of course this card is phased out and you will probably not made and 3DMark world record with it, recapped or not, but for testing or normal office use it is perfect. Thanks to it's passive heatsink and small size it is preferred graphic card, where you need just one to be. I use these cards in folding and testing machines 😉
I do, on the top of that, use a little osciloscope 440 Scope Plus http://www.atcweb.com/tpi440.htm - http://postimg.org/image/qc1qqciol/ 😉

So, let's first take a look at the card itself:

As you can see, we gonna need:
1x 1000uF 6.3V d8 Samxon GC
4x 470uF 6.3V d6.3 Samxon GD
3x 10uF 25V d4 Samxon ZS

Let's take a look at the original caps…

…well, it is obvious they gotta go. Asiacon is the same as Evercon and this is the same cr*p as G-Luxon... :mad:

Step first - desolder with the soldering iron the caps:

Every time before use the soldering iron, dip it to the resin to protect against oxidation not only the contacts, but the actual soldering iron how wire tip. Result did not look ver pretty, but caps are gone now 😄 The white or shaded (or other way highlighted) holes are typically for the negative cap polarity wires. Of course you gotta stay alert for exceptions and crazy designs, witch can swap the polarity! Sometimes it is better first take a picture of the card to have proof on how it looked before… 😉

Now come the hardest step - suck off tin from at least one of the holes. Choose the one that is isolated from the rest of the PCB. This way you heat up most only small piece of tin and PCB and hence you should be able to suck the tin off easily.

Result - one hole is free.

Now take the replacement cap - take care about the polarization (on some cards, such as Gigabyte FX5200/FX5600XT, it is contrariwise!). Caps has one longer leg, that is the positive wire. If you have free the positive hole, you are good to go. Insert the longer positive wire inside and the negative adjust to be pressing exactly against the tin in the not free yet hole. Apply only light pressure. If you need more pressure, shorten the wires, but leave the positive wire longer.

From the bottom side heat up the tin in the negative hole and after a while (depends how big area of PCB you heating up) the cap nicely slide in place. Looks this way:

If you got free the negative hole instead, then cut the positive wire of the cap in middle, so it get shorter that the negative wire and then work it out same way.
Caps wires should be put thru to the end. Exception from this is only when you solder smaller or bigger spaced cap into holes that did not match. In that case - depends on how much the wires are getting dilate or closer - leave at least 3mm for the bend. Pressing too much in this case is very likely to damage almost any cap!

When you have the cap in place as it should be, then cut off the remaining wires. Leave just about 1mm from them. And then with plenty of resin again solder them.

Now it does not look pretty at all, right? 😮 Well, let's continue till we have every caps soldered first.

Now will come the technical spirit in action. Using brush add the spirit in place where the resin is:

And leave couple of seconds to take effect. You can see that the resin is breaking up and melting already. You can help big chunks get off by sharpened piece of hard wood - notably increasing the rate how the resin leave the PCB.

Then first with rubber, also wetted in spirit, rub off the remains of it. Last small remaining of the resin is best to get off by brush, wetted in spirit again. The brush has to have reasonably tough strings.

(image also show desoldered CE filters and coils replaced by pieces of wires)

With careful clean up you can get professional looking soldering joints.

And now you can only be delighted looking at how the new nice caps beautifully looking at the card.

Whole look on the card with now exchanged caps.

With such simple graphic card with minimum caps you can be done in like 10 minutes top. And with a little work you got the assurance it will not fail you for years and years. And now back with it to the computer 😉

PS. sometimes happens - especially with small caps, where one can heat up with big soldering wire tip both holes - that it is possible solder the cap w/o actually sucking off the tin. Sometimes this is also the only one possibility,  when the tin did not want get off and you did not want to damage the PCB… In this case simply cut the legs to be same and much shorter (so you can apply more pressure), align them right to booth holes, hold and from the bottom start heating and push... 😉

Trick with dental pick 😉

The hardest part on recapping is cleaning the holes for new caps. So, there come a little trick…

Yep, with this is the very same dental pick your dentist use to push on your teeths. You can buy it in medical supply shops, the only slight disadvantage is that the quality ones cost premium. But the vacuum tin sucking toy is not even recommended on BadCaps, because from heated PCB it easily can suck-off small traces, or by the back impact it tear them on the mobo. Sometimes it happen for me and certain low-quality mainboards (like JetWay V266B, Abit BX133 and so on) are very prone to this.

So, at first we have holes after desoldered cap (or never soldered cap there) full of tin:

So just attach the pick and reasonably push on it with one hand to stay in place (beware, it is very sharp, be carefull!):

From the other side heat up the PCB with iron and soon the pick do thru the hole like hot knife thru butter and try to push it as far, as you manage with reasonably small force:

Immidetelly after you reach the end, start wriggling with it to sides/up and down a bit, so it will not stuck to the tin or resin in the hole:

Now the big metal chunk of this dental pick come to play - it disperse the heat perfectly, so in just a few seconds we have a free hole:

Now let's repear that with the second hole, when we want to solder the cap inside easily (or he is on wrong place with bad access):

Push a little and we are on the second side easily again:

…and now we have both holes free and perfect for soldering new cap in:

As you can clearly see, this methos is easy, comfortable and fast. And the dental pick clean really well. Tin does not get attached on it at all and resin only very lightly. Cleaning with piece of old clothing and technical spirit is done in few seconds. The steel is very high quality, elastic a little and very hard to break. Almost impossible, I never managed it yet and I tried 🙂 Comparing that to the nevereding cleaning of the vacuum tin suction tool… well, this is not comparable at all. Productivity in recapping go very much up using dental pick. Caps almost like jumping in the board 😉 😄

Sometimes it happens that in the holes remain too much tin, that create knob around the holes, where capacitor will be soldered. Such knobs that are on the top of the PCB are easy to tear off by nail or cut off by scalpel.

Soldering was made by my 75W transformator solder, using lot's of resin. Pictures are not retouched at all and I did not even clean the board before taking the pictures. Board in question is Compaq Evo D310 one (MSI 6541 v1.0), exchange 10pcs of 1000uF 6.3V G-Luxon crap caps for 13pcs 1000uF 6.3V Samxon GC caps.
Board works well 🙂

Some people prefer solder wick and soldering station:
http://www.youtube.com/watch?v=htrcZuK_ZsY
Also a way to go.

I use the dental pick method…. except I use a safety pin in it's place.  I clean up extra solder with braid.

Whatever you can fit in the hole does the trick. Best is quality steel, because solder did not stick on it, so…

I was under the impression that safety pin is relatively serious in diameter. Most of the holes I need to punch thru are very, very small and even very thin dental spikes are almost no-go in there... But I quess that either you do recap only PSUs with huge holes, or the safety pin is much smaller that I think it is... But like I say - anything could work.

Measuring caps using ESR60 Enhanced tool, that have this specs:
Capacitance: 1 - 22 000uF (0,47uF capacity it does not measure, 1uF do)
ESR: 10 - 20 000mOhms (all bellow 10mOhms is shown as 0,00Ohms)
Measure at frequency 100kHz
It can determine, when cap is leaky and therefore bad (In-Circuit/Leaky message)
It does calibrate it's electrodes, so it can measure ESR of the cap in as low values, as 0,01 Ohms

So I looked at my pile of caps:

…and tried it to see, what can I expect from the caps:

Vent 3300uF 10V from Enermax 620W Liberty PSU, desoldered after 5 years of usage:

3494uF 10mOhms - surprising!

Hitachi HP3 390uF 400V from Enermax 620W Liberty PSU, desoldered after 5 years of usage:

357.4uF 180mOhms - pretty solid

New Panasonic TS-ED 470uF 400V

405.4uF 140mOhmů (uhm… 400V caps is probably not really measurable well at 100kHz and low voltage...)

New Samxon URL 1000uF 6.3V polymer

1134uF and under 10mOhms ESR 🙂

New Samxon URL 470uF 16V polymer

477uF 10mOhms ESR

New Samxon RS 47uF 35V

49.89uF 250mOhms (classic RS cap)

New Samxon GK 220uF 25V

210.8uF 60mOhms (for first time used after like 4+ years in the bag it reported that the cap is leaky… on second try it started working again well)

New Nichicon LE 820uF 2.5V polymer

777.8uF and under 10mOhms ESR (capacity is little disappointing to me)

New Sanyo SVP 180uF 16V polymer

189.7uF 20mOhms (a little bigger ESR for polymer…)

New Panasonic FM 3300uF 16V

3473uF 20mOhms

New Samxon GC 3300uF 6.3V

3439uF and under 10mOhms ESR 🙂

New Samxon GA 3300uF 6.3V

4435uF and under 10mOhms ESR 🙂

Vent 3300uF 16V  from Enermax 620W Liberty PSU, desoldered after 5 years of usage:

3296uF 10mOhms - very surprising!

New Samxon GK 220uF 16V

209.9uF 40mOhms (and this one worked on the first try)

New Samxon RL 4.7uF 50V

4.5uF 1150mOhms (how lower can I go?)

New Samxon GK 47uF 25V

45.86uF 220mOhms

New Samxon RL 1uF 50V

0.99uF 1850mOhms (so well, 1uF is possible to measure, 0.47uF caps are not measurable 🙂 )

Surprise is the very good parameters of the Vent caps, desoldered from old Enermax PSU and the high overcapacity in the GA cap.

What all this will could interest others? Well, I can measure any cap for you 🙂
Of course it need to be shipped to me, but I can measure not only the capacity, but the ESR too, so we can see and compare, how bad the cap are. No returns are realisticaly expectable, tough. Surely no-one want to store or even return bad caps, huh?
Address will be sendt in PM for these who would like to know - postage cost of evenlope from Australia to Czech republic was $3.5 AUD, so it is not that bad 😉

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