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Practice before you start repairing a board : The most important thing to do before you start to work on a board which you want to fix properly is to learn the technique properly by practicing on a trash motherboard. It is all good and well to be reading up on the technique but when you start to put it into practice you will find that it is a little more difficult than it sounds. Don't worry because after practicing on a trash board you will learn the technique properly. So get some of the cheapest capacitors, remove the old ones from the trash board and install them. Read some of the links I have put at the bottom of this page. The most important thing is to learn what is a good solder joint and learn to do that well before you start. The capacitor removal is actually the easier part.
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Prepare your workplace : First of all prepare your workplace so that all tools and parts are handy and you have enough space to work. It breaks your concentration when you are searching for some part or tool during the recapping. Get your board holder positioned so that you can work comfortably. I am right handed so i have the board angled a bit so my right hand with the iron can heat up the pads on the back of the board and the capacitors on the front of the board are facing me. Have a desk light shining on the area, you will need lots of bright light to work properly. |
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Clean the board : give the board some blasts with canned air to blow away all the dust, it is better to solder a clean board. |
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Safety First : have your prescription glasses on when you are working or otherwise use some safety glasses/goggles, this is to prevent flux splatter or even the iron slipping and hitting you in the eye. Make sure that the cables to the soldering station are not in a position where you will step on them and pull it off the table. When you are not using the iron it goes back in the iron holder, do not leave it on the desk. The iron is extremely hot and will burn you or burn a nice line in the carpet if you drop it. |
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Make sure that all your workpieces are steady and you are paying attention to what you are doing. Make sure that everything is in a position comfortable to work. When things are unsteady or when you are tired that is when you will make mistakes and burn yourself or destroy the board. If you are tired, under a tight schedule or getting angry/frustrated then forget the work for the next day, it will just be sloppy work and not worth doing. You may also want to do part of the job one day and some more the next day. A whole board is a lot for a beginner to do in one sitting. |
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Do not eat or smoke when you are working, the solder and chemicals are toxic. Wash your hands when you are done. |
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Heat up the iron : Before you start to work, set the iron to 450oC and leave it for a while in the stand. Dont start work immediately, let the iron warm up good for 10mins or more until it is optimally hot.
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Remove all components from the board : It is pretty obvious that you will need to remove all ram, cpu, cards, cables from the board before you start working. You need as much access to the board as possible and you dont want to damage the components. |
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Make a diagram : of the positions and values of the capacitors that you will remove on the board. Make sure that you note where the negative lead of each capacitor is on the diagram. The negative lead is marked on the capacitor with a stripe down the side. This stripe matches the white hemisphere around the hole for the negative lead on the board stencil. This diagram is a useful tool for final checking before you power up the board. |
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Mark on the actual board : the positions where the board stencil says that capacitors should be installed but they were not. Due to design changes they might have changed the specification after the boards were made. Do not install capacitors in these positions and mark on the board with a marker pen an X on these positions so that you do not make a mistake and install a new capacitor there where it should not be. Make these marks because it is easy to get confused when you are doing the job. |
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Put your wristrap on : Get your antistatic wrist strap and have it on the wrist of the hand using the iron. Attach the other side of the strap to the rear of your computer case or another good grounding point. Always wear the wrist strap while you are working or holding the board. |
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Put the board in the board holder : In order to remove the capacitors you will place the board in the board holder so that the caps of the capacitors are facing you and you will be using the iron comfortably to heat from the rear of the board. Below you can see the board in the position for removing the capacitors. You will orientate the board the best way that the capacitors you are removing are closest to you. So in the photo I would be working on the capacitors at the top edge of the board and then flip it over to work on those near the PCI slots. |
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Removing the capacitors : heat up one of the capacitors leads from the rear of the board so your iron is contacting the pad around the hole and the lead. Then apply a touch of solder to the solder already there. This is important because it will assist you in heating all the solder quickly and removing the capacitor. Do the same to the other lead. Then you will heat again one of the pads and leads and wiggle and push the capacitor towards the other lead. Then do the same with the other lead. You will make your own technique here. Some people like to heat both leads and wiggle them out at the same time. Others like to alternately heat and wiggle each lead until the capacitor is free. Or even get one lead completely out and then work on the other. |
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Remove the capacitors gently : the most important thing is to ensure that the capacitor is coming free of the board reasonably easy, that all the solder in the hole is heated before you start pulling. If you are having difficulties then try the alternate lead heating method. Dont rush and dont force it because you may damage the board. If you are having big problems heating the solder then maybe your iron is not hot enough, does not have enough wattage or the tip you are using is a bad design. Some solders on boards are stubborn though. |
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Clearing the hole from solder : Once you have removed the capacitor you will need to clear the hole of solder. Some prefer to leave the solder in and then install the cap by heating the other side of the board as you push. I think this method is not the easiest. In order to clear the hole you will need a soldapult/solder sucker/solder pump, a cheap desoldering tool which is a suction device. You compress the lever and then it is locked and when you press the button it sucks the solder away. Get a standard sized one not a mini one. You can find these at any soldering shop. Recently i have purchased one from Piergiacomi of italy to replace my chinese one. The Italian one cost 8 euro, the Chinese 1.5 euro, go figure. anyway the job is so much easier with the Italian tool. |
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Heat up both pads on the front of the board : I usually do this for a few seconds before heating up the back, this seems to assist and pushes any excess solder from the capacitor removal into the hole. When you have the iron at the front of the board you have to be very careful that the iron is aligned perpendicular to the board and you will not come in contact with the hot iron against other components or slots. Think out the movement before and be careful.
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Position the solder pump : flush against the hole on the front of the board and then heat up the correct hole by contacting the iron in the middle of the hole on the back of the board for some seconds . You will then check that the solder pumpis over the middle of the hole and then press the button while the iron is still on the hole at the back of the board. This is where your board holder is most useful because the board must be very steady otherwise you will not stay in the middle of the hole with the solder sucker. |
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Clean the solder pump : when you have done one hole press the solder pump so that the inside at the front is exposed and then clean the solder from the solder pump with your finger. It is essential to have it clean to do good work. |
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Check how you did : using the desk lamp at the back of the board check to see how clean the hole is. Did you do a good job, if you did not dont worry, if you fail to clear the hole completely you may try again but only once more. If you still fail to clear the hole, dont worry you may use TCs needle technique. |
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The needle technique : TC recommends using a stainless steel dental pick. I have had good success using a stainless steel sewing needle. What you do is heat up the hole on the back of the board and insert the needle into the hole from the front of the board and wiggle it around while still heating until you clear the hole. When you come to install the new capacitor you will realise whether you have cleared the hole enough. Dont force the capacitor lead into the hole, you must try again with the needle to clear the hole better. |
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Clean around the hole : When you have finished look at the front of the board and clear excess solder from the holes using a finger nail, piece of wire or razor knife. Dont scratch the board while you are doing this, you may damage a wire trace. Better to clean only where it is going to make a short and then leave the rest than damage the board. |
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Trim the new capacitor lead : when you are ready to install the new capacitor. You will decide whether you like to trim the leads to about 1cm small or leave them long before you install. If the hole is small then it will be easier to pass 1cm of leads through rather than the whole lead. |
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Remove the board from the board holder : in order to install the capacitor you will have the board flat on the table. |
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Check for the negative lead carefully before you begin : Look at the front of the board, you will see a white semi-circle or mark at one side of the circle. You must match up the white/silver/gold line that goes down one side of the capacitor with this white mark. This shows the negative lead. Pay attention to this it is important, the capacitor will blow if installed incorrectly when you apply power to the board. |
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Do not force the capacitor leads down the hole : you must bend the leads together slightly so they are going to go down both holes nice, do not force the capacitor, if you have problems bend the leads some more or maybe you will have to clean the hole better using the needle again. If you force you may damage the foil around the inside of the hole. |
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Do not bend the capacitor leads outwards to hold it to the board : You may think that it would be good to bend the leads of the capacitor outwards once it is in the board in order to help it stay on the board while you are soldering. This is incorrect. You must have the leads standing up in the centre of the holes in order to solder well. You will take the board from the board holder and have it upside down on your table. This is where some little boxes or other things of various heights will help you. You will need to make the board stable and also to support the capacitor that you will be soldering using a little box or something between it's top and the desk so it is flush to the board and standing straight. |
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Solder the capacitor in : when the capacitor is supported flat against the board with the little boxes on the underside and the rear of the board is up on the table you can begin. You will heat up both the pad around the hole and also the lead with the iron. You will choose to position the solder at a point where there is an obvious space between the lead and the pad around the hole. Have your iron at the other side. Then you will feed solder into the hole. If you have difficulties heating the lead and pad enough you may touch the solder quickly on the iron and then feed down the hole. |
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Learn what is a good solder joint : You will probably realise that you needed less solder and time than you imagined. Check with the links below and understand what is a good solder joint and then try to make the next one better. This is where technique is difficult to teach. You must understand a good solder joint and then modify your technique until you achieve it. I think that the 450oC may be too hot to achieve a perfect joint though but it is easier to have the iron the same heat as to remove caps. The perfect solder joint is just enough solder to make a good connection. The solder does not make a ball around the solder pad, it curves from the lead in the middle down to the sides of the pad. Dont worry that you did not make a nice joint, as long as the joint is nice and shiny and the solder went down the hole you will learn to make nice solder joints with practice. Do the other lead now. |
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Clip the leads : When you have finished you will use a small pair of wire clippers to clip the excess leads. I recommend the 8PK-30D from Pro's Kit which is a great taiwanese company and not very expensive. Big standard wire clippers will not do a good job, you need proper micro clippers, these are also useful if you want to trim the leads of the capacitor before installing. Clip the leads similarly short as other components on the board. |
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Replacing an array of capacitors : When you have a row of capacitors to replace or two capacitors near each other you will need to remove them all. Then you will have to try to replace them in a nice looking way. You may have problems because the replacement caps are 1.0cm width rather than the 0.8cm width installed on the board already. You will need to bend the capacitors leads before installing to have some of the row bending to the left and the others bending to the right. Otherwise as TC says you can install a capacitor lying down. Be careful that the capacitors you are installing will not affect installation of a CPU/Heatsink, AGP card, ram etc. Most of all dont get pissed off and start pushing the caps around. Do it all gently and if it will still look like shit at least your board will still work because you were gentle. if you are getting pissed off then forget it, think it out better and try again tomorrow because calm work looks more pro. |
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Beginner's tip : If you are a beginner you may like to do a few caps and then check that your board still posts, then continue. If your technique is no good then you will know before wasting a lot of caps and at least you will know which area to look for the problem. It will also give you confidence when you know the first caps you did were nice. |
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Do not reheat the solder : It is not recommended to reheat the solder you have applied to new caps and then apply more if there is a problem. This may result in a worse joint. Better to do the entire process to remove the cap, clean the hole and start again. |
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Pay attention : when you remove capacitors, check the values of the capacitors before you remove them. It is easy to mistake a lower value for a 1000uf and remove it by mistake. If you did that you can clean the hole then resolder it carefully and it should be ok. |
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When you are finished clean the board : When you have finshed you will need to clean the flux from around the solder joints and also the flux splatters which may be around the board. You will need to use a FLUX-OFF spray. I am using one from Cramolin which is called FLUX-OFF and is dimethoxymethane. This will damage plastics and PVC so you will spray a little around the solder joints and manipulate the excess using a cotton bud or Q-tip (normally used for cleaning your ears) so it does not flow down a hole to the other side of the board. Then you can rub the excess flux around the joints using the bud. After doing all the joints and checking for ones i have missed i leave the board with a halogen desk lamp (or other hot desk lamp) about a foot from it for 10mins to ensure that all the FLUX-OFF has evaporated. It is highly inflammable so no smoking. |
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Visually check the board : for little pieces of solder or other leads that have stuck to the board and may make a short. I also blast the board on both sides with some canned air for the same reasons. |
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Check the board against the diagram : see that the capacitors you have installed are the correct values and are installed in the right direction before you apply power to it. |
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Apply power to the board : with processor/ram/keyboard and floppy disk installed and while connected to a monitor. Don't jump to the conclusion that you screwed the board on the basis of the boards leds which show a post error. Check your monitor connections, ram seating, cpu seating before you decide you made a soldering mistake. I guarantee that if you were reasonably careful you will get a boot. The boards can take some soldering abuse. If you burnt or scratched some board traces while you were working or have a short that is another thing though. |
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Run test utilities : first I would start off booting a ram test utility disk and checking for ram errors, then you can run some burn in utilities and you would want to see the board totally stable after running them for some days. |
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Good luck with your new board. : DIY will make you very happy and you may go on to some other soldering task such as making a stereo amp kit or something. A worthwhile way to pass the weekend and very rewarding. If you progress to doing nice looking cap replacements then you can start doing your friends' boards as well and make some money. If you can do this work then you have nothing to worry about, many component failures are due to bad caps. You could even progress to buying stuff with bad caps for cheap and repairing it yourself. |
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Some of my efforts are below and I would not call myself an expert. You can have the same success also as long as you follow the instructions carefully. |
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3com Officeconnect 8port hub - I did 3 of these replacing each time 4 caps with Panasonic FC at a cost of 3 euro. Now they will last for a very long time. 3com was very cheap in specifying crap caps on these units to save so little money in the end. I would not recommend these units to friends. |
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MSI MS-6337 815e board, replaced all the caps with Panasonic FC, works fine now. That is a good board for recapping, very easy to work on. |
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MSI MS-6163 Pro - replaced all the caps above 1000uf with Panasonic FC. You can see that I had great difficulty installing 10mm caps at the positions where there were 8mm. I had to put some caps at an angle. It looks pretty bad but the board works fine. |
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Here are the links for you to check : |
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Elecraft Builder Resources (Click on Soldering Tutorial)
http://www.elecraft.com/Apps/K2info.html |
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Apogee Kits Downloads (Click on ApogeeKits Free Illustrated Guide to Electronics Soldering)
http://www.apogeekits.com/downloads.htm |
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The Basic Electronics Soldering & Desoldering Guide
http://www.epemag.wimborne.co.uk/solderfaq.htm |
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