bit OT: tips wanted for changing mobo capacitors

[dai h.]

sry, this is a bit OT. Okay, so I tried adding a couple of alu electrolytics to my mobo and had a really hellish time just clearing out some of the holes of solder from the power/ground planes sinking away all the heat. After only mostly clearing the hole halfway, finally was able to achieve some success using the fattest part of a (huge) tip and making most of the tip have good contact with the board, plus for some holes with not so much mass, some tricky moves w/the solder-wick the iron (putting the corner of the wick in to soak some of the solder, then moving the screwdriver blade <of a different iron--a Hakko "Presto" 20W with momentary 130W button> flat against the wick), but it was all too hellish and nerve-wracking to try to do the same way again (and the board in some of the parts is not looking great even after cleaning). So I'm thinking I need something that has really high power (150 to 200W?) so I can get in and out quickly as with more normal-sized work. Is the gigantus iron a bad idea (I'm looking at a Hakko "Matchless" and "Junior")?

http://www.sourceresearch.com/hakko/...less-irons.cfm

http://www.hakko.com/japan/products/hakko_junior.html

Maybe some trick of the ninja I am missing? Any tips for mere mortals someone would like to share?

thanks,

Dai

[Enzo]

Yes Grasshopper, Ninja trick is throw that wick across the room and use a sucker. Wick take heat to get it hot enough and that is heat above and beyond what the board needs. The iron cools itself from the sink action while it is trying to heat things. If your iron alone will melt the solder, then a sucker will pull it out. A desoldering iron really rules, I'd feel lost without it. On really stubborn things, I can hold my iron on the work next to the desolder iron for a moment to start the melt.

But even without the desolder station, I prefer the tubular cock it and press the button suckers. They work, I have never had the rubber squeeze bulb kind wirk very well. I have had the plastic ones like SOldapullt, but I prefer the metal ones. I get them from various surplus outlets cheap.

Get the solder melted, put the sucket tip right on top of the joint, right on the iron tip, don't pull the iron away. Trigger the sucker and poof, hole is empty.

ANother trick is to ADD solder to a hole before trying to clean it. The fresh solder will melt easier and flow into the rest of the old solder. Not unlike getting a sponge wet before wiping up water on the floor.

I almost never use wick. if it works well for you most of the time, please use it most of the time, but it doesn't work well all the time. Suction works well.

[dai h.]

thx Enzo (that was quick). I think did manage to clear one hole with a bulb, but it's tricky since you can't see the other side (have to stay aligned) and I think for most of the other holes, there just wasn't enough wattage. I was just thinking the fundamental problem was that I needed more power but I'm not exactly sure how much and as a side note if I needed to worry about a non-grounded tip(this mobo--the one I worked on--I did use non-grounded irons, but it seems to have turned out okay*knock on wood*). Those desoldering irons, they look very handy on paper, but seem expensive which is okay if I can get something guaranteed to work I suppose. Have you ever used them on the same sort of boards (multi-layer, through hole plated, etc.)?

[dai h.]

just to add:

But even without the desolder station, I prefer the tubular cock it and press the button suckers. They work, I have never had the rubber squeeze bulb kind wirk very well. I have had the plastic ones like SOldapullt, but I prefer the metal ones. I get them from various surplus outlets cheap.

I hate those cock-action. Prefer the rubber bulb w/Teflon tip for big solder blobs/joints.

ANother trick is to ADD solder to a hole before trying to clean it. The fresh solder will melt easier and flow into the rest of the old solder. Not unlike getting a sponge wet before wiping up water on the floor.

right, more fresh rosin. I'm no expert by any means, but I think I know most of the basic tricks.

I almost never use wick. if it works well for you most of the time, please use it most of the time, but it doesn't work well all the time. Suction works well.

the wick is good for getting the bits of remaining solder to get the pad/joint all clean of the old solder. It just all depends I guess on how good someone is with the sucker or wick. Getting all the old solder off in one move with either would probably be the ideal master ninja move.

[Sock Puppet]

Another technique is to push a pencil lead through.

S.

[MBSetzer]

I like the metal solder suckers with the teflon tip myself, and I also sometimes place the point of the iron on the joint to be unsoldered, then immediately touch the sucker tip to the hot iron right above the hole, then when the solder melts let it overheat a fraction of a second before pulling the iron away and pushing the somewhat softened and preheated tip against the joint and sucking hard. Better than touching a cold tip against something you want to stay molten. Teflon can take a lot more heat than other plastics.

To clear a plated-through hole which doesn't have a component any more, you almost need to have the tip of the sucker completely vertical above the hole, without it being too soft and deformed since it helps if it makes a good seal.

Where I always deviate from most professionals is I never use a temperature-controlled soldering station for anything, I just use a cheap 25W regular soldering iron from Radio Shack the same way I have been doing for over 4 decades. While expecting equal or better soldering results the whole time. Due to oxidation I rinse the tip with fresh solder before each joint, so approximately 90percent of my purchased solder is wasted (but recyclable) I start out with the 25W tip but it gets eaten away as the solder dissolves the core faster after the outer plating has worn away. So I replace it with the 30W tip after it gets too short and runs too hot. In regular use I'll wear it down shorter than a new 25W tip before I discard it anyway. Only a brand new tip can truly be tinned in the most desirable way, and it only retains its point for a few dozen hours before the plating wears through, then the core starts dissolving much faster with each tip rinsing. So most of the time even on some surprisingly delicate work I am using a soldering crayon rather than a soldering pencil.

For a delicate plated-throuh hole this would be one of the few areas where I would break out a new reserve tip to put on the iron, since the ground plane is an issue I would use the 25W tip on the 25W iron rather than a new 30W tip. I never use 30W irons since the full contact made by the usual crayon-shaped tip from a 25W iron is enough to solder to the back of pots. The only difference in the 25W & 30W tips is the length of the shaft before it comes to a point, the 25W heating element after it is fully warmed up runs at constant temperature internally, then the tip temperature is dependent upon its length and subsequant distance from the heating element.

Then I tin a new tip by heating the iron and babysitting it by touching solder to it repeatedly until it just melts and flows on before the tip gets a chance to oxidize itself. Then unplug the iron and hang it tip-down with a drop of solder remaining and allow it to cool until the solder hardens. I store new tips pre-tinned in this way, you can not see the point until you reheat the tip since it is surrounded by a drop of hardened solder.

So I would put on the new 25W tip to the 25W iron, plug it in, wait for the tinning to melt, sling it into the recycle pile then rinse with fresh solder, only Kester No.44 will do, then poke the sharp point of the new tip as far into the plated hole as you can from the complete vertical position, slightly overheat the solder (watch it just as carefully as you would with a 120W soldering station) to give yourself enough time to quickly replace the iron with the precocked solder sucker, then vacuum abruptly. I would not worry about the sucker having a cold tip in this case since it will not be touching any molten solder, just forming a seal around the PCB hole. Quickness counts, especially with that ground plane.
Alternatively, place the sucker well-sealed in position at the PCB hole, then attack the other side of the board with the soldering iron, lifting briefly to let air pass when you actuate the solder sucker. Both the sucker and the iron would be vertically opposed this way so it would be best with an assistant.

Mike
As always, if the workpiece is critical, practice on scrap PCBs beforehand.

[dai h.]

thx Mike and Sock Puppet.

I like the metal solder suckers with the teflon tip myself, and I also sometimes place the point of the iron on the joint to be unsoldered, then immediately touch the sucker tip to the hot iron right above the hole, then when the solder melts let it overheat a fraction of a second before pulling the iron away and pushing the somewhat softened and preheated tip against the joint and sucking hard.

yeah, that'll work for more normal boards, but I don't think the big power and ground planes give enough time to keep the solder molten.

Where I always deviate from most professionals is I never use a temperature-controlled soldering station for anything, I just use a cheap 25W regular soldering iron from Radio Shack the same way I have been doing for over 4 decades. While expecting equal or better soldering results the whole time.

I use cheapies too. Wonder if they had temp. controlled irons back in WWII days. The joints on octal tubes from back then look real good, for one.

then poke the sharp point of the new tip as far into the plated hole as you can

that's an idea. I cleared some holes on a Mesa/boogie from the bottom, but I'd rather not do those contortionist exercises if I can avoid it. I was also thinking (for through-hole plated holes), to cut a piece of part lead, stick it in the hole to use as a sort of guide pin to put the sucker tip on to. Took me forever just to clear a couple of holes, so I basically just want something that'll help move things along much faster. I found a bunch of swollen electros in a PC my brother was given by his friend. Looked like it was worked hard for PTP file sharing, left on 24/7 prob'ly. Some 3300uF around the CPU and seems like just recent a 4700uF looks about to go, so I wanted to practice and figure things out better so I can do a clean job.

[Enzo]

Desoldering stations work very well. They start at a couple hyndred collars and go up from there. My very basic Pace unit costs abut $600.

I don't like the squeeze bulbs because they don't suck as hard as the cocked kind, and I find it clumsier to both maintain a squeeze motion and an aiming motion at the same time with one hand.

I don't think the big power and ground planes give enough time to keep the solder molten.

SOunds like you are pulling the iron away. I place the iron on the hole and melt the solder, I then press the teflon sucker tip down over the iron top and joint. I trigger the sucker. I don't pull the iron away, the solder flows around the tip into the sucker. I don't care how fast you are, if you pul the iron away just before you suck, it doesn't clear solder nearly as well. The solder stays molten because the iron stays on the joint.

The desolderer clears holes pretty well. But if I want to clear an empty plate through, I just fill it with fresh solder, then hit the hole with a sucker. Even the cockits will work OK. The hole fill of solder all comes out at once. A half full hole won't clear itself as well.

In the WW2 days they were not soldering to printed circuit boards, so controlled heat was less of an issue. They had no traces to lift off the boards.

it's tricky since you can't see the other side (have to stay aligned)

You are heating on one side and sucking on the other? I almost never do that. My iron and sucker are right there together on top.

On a two sided board like Mesa uses, I rarely have to demount the board. I get under the component lead with a small hook, heat the solder and pull the part from the hole. Once the part is out, I then refill the holes and then suck them clean. All from the top. Trim the lead length on the new part before stuffing it on the board, then solder in place. The plate through flows the solder through to the far side. New part is installed and the board stayed home.

[MBSetzer]

Another thing I have done since I have been using only the most basic of desoldering tools is to push a length of fresh stripped copper wire into the hole, then pull it through while the solder is cooling.

Also IIRC if the wire hardens in the hole before you get it out, then you can heat the wire a fraction of an inch away from the hole and get the wire loose without having to add more solder.

I also assume you know about the electrolyte scandal where large numbers of MB electrolytics were defectively manufactured over a period of more than a year due to incorrect electrolyte resulting from a stolen formulation which was supposed to be high-performance but turned out to be substandard instead. This was late '90's or early '00's IIRC and what I read seemed to indicate huge exposure by the major Taiwanese component vendors and massive incentive for laundering the *NOS* merchandise (perhaps later on in the future) rather than suffereing losses.
You can check the web for identifiying details of known mainboards and capacitor descriptions to help see if this factor is a potential source of problems.

Mike

[dai h.]

Desoldering stations work very well. They start at a couple hyndred collars and go up from there. My very basic Pace unit costs abut $600.

$600. Ouch. That's too steep for me, esp. for my hobbyist use. Probably have to pay something like that to get a good one though, I'd guess.

You are heating on one side and sucking on the other? I almost never do that. My iron and sucker are right there together on top.

yes, but maybe I was missing keeping the tip contacted to the hole. I'm really out of practice, haven't soldered 'til this week for maybe 8? months. Doing things upside down was from me thinking gravity would help if I heated and wicked from the bottom (the hot solder would fall downwards due to gravity).

Another thing I have done since I have been using only the most basic of desoldering tools is to push a length of fresh stripped copper wire into the hole, then pull it through while the solder is cooling.

Also IIRC if the wire hardens in the hole before you get it out, then you can heat the wire a fraction of an inch away from the hole and get the wire loose without having to add more solder.

I was trying to do something like that, putting a cut cap lead so I could work the solder in the hole more to one side (top or bottom) but I couldn't get it to work.

I also assume you know about the electrolyte scandal where large numbers of MB electrolytics were defectively manufactured over a period of more than a year due to incorrect electrolyte resulting from a stolen formulation which was supposed to be high-performance but turned out to be substandard instead. This was late '90's or early '00's IIRC and what I read seemed to indicate huge exposure by the major Taiwanese component vendors and massive incentive for laundering the *NOS* merchandise (perhaps later on in the future) rather than suffereing losses.
You can check the web for identifiying details of known mainboards and capacitor descriptions to help see if this factor is a potential source of problems.

right, someone here put up a link to an article discussing the defective cap electrolyte some time ago. With my situation (two power supplies and my bros. mobo) I'm guessing it was just due to use that they went bad, since the ones in his mobo were Japanese manf.'ed (Nichicon?). The ones in two power supplies did look like Taiwan (G-Luxon, and some other brand), maybe China manf.'ed, but I'm thinking those were just due to constant use and maybe the higher power consumption of the CPU (Pen4--some of the newer ones are supposed to be more efficient, the new dual core thing and some of the CPUs meant for notebook PCs). On mine, I just wanted to add some to hopefully get more headroom during peak operation (high CPU usage) like for virus scans or whatever.
This is the page I saw that inspired me to try that:

http://www.finetune.jp/~lyuka/interests/pc/p4c800e.html

Mine is an older p4pe, but looks pretty similar. The pic where the "Vcore regulator output capacitor" is shown looks the same. Not much space on top and on the bottom esp. for an iron with a large tip, you also have to avoid other non-related solder joints. Basically just trying to add four caps (where there wasn't anything). I bought the same type except from a different manf., instead of Sanyo, and unfortunately the leads were too fat for the holes so I bought a couple of the same type (low impedance alu elects.) instead. It was interesting looking at some of the manf. sites for alu. electrolytics, some were very long life types maybe rated 20,000 hours or something like that, but typically physically bigger which means they won't fit (bigger = less heating = longer life?).

anyway, back to my original question about trying the 150W-200W iron with not tiny but reasonably small tip--do you guys think there is a good chance of a very high watt iron giving the same sort of usage (quick on, quick off) as a 30-40W on a regular PCB with not so much mass (big planes, multilayer, etc.)?

[Rob Mercure]

Dai,

I'm not sure what materials you have available - as opposed to the USA - but you might want to just "custom" make soldering iron tips. Many of the inexpensive irons use a tip that is essentially piece of "thick wire" (solid metal cylinder) that slides into the barrell of the soldering iron and held in place with a set screw. As luck would have it the hole diameter is often around 0.2 inches which is also the same diameter as the 4 gauge copper wire used to connect electrical panels, etc., to earth ground (60 Amp transmission wire).
Copper being quite maleable it's easy to cut a couple of inches of 4 ga. and using an "anvil" and hammer/grinding wheel craft whatever shape you need to create a tip that will transfer heat to the work as efficiently as possible while maneuvering around surrounding parts (I use an old piece of rail as an anvil). I can often pick up these soldering irons at flea markets for a dollar or so each and I've got several tips that I interchange among the best of these irons while having a couple of irons with a "dedicated" shape that I use frequently.
While probably not applicable to your specific need soldering guns have some of the same flexibility. The common "Weller" style's tip is a piece of wire around 10 ga. (0.1") and I've made all sorts of tips including, literally, one to reach around a corner so that I could loosen a terminal that lay underneath an easily melted plastic part.
If you are quick you can even drill a hole in a piece of broom handle and jam a piece of 4 gauge wire in and heat it on the burner of your stove (camp stoves work well for this and I keep such an "iron" in my glove box).
As to temperature controlled stations I've not been convinced that the benefits justify the costs for the casual user. I've had good experiences using them when I worked in high volume repair shops primarily repairing PCB units but at home I use a variety of irons/guns and a variac - and when I was using the controlled stations I still had to often custom crafedt tips that would let me apply heat specifically.

Rob

[dai h.]

thx Rob for the additional advice and tips. Took Mike's advice to get some practice, and last night tried soldering/de-soldering on a PCB I had damaged when I started out DIYing. It was the board from a Yamaha REX50 multi-efx. unit, double-sided, thru-hole plated, close to a motherboard in construction. Used the Hakko Presto with the screwdriver tip, and found that it seemed to go a lot easier than the mobo and I don't think I used the boost function much (button on the iron to temporarily increase wattage to 130W--30 seconds max). I was able to evacuate some holes from the top (same side as the iron) with the bulb, the holes connected to big plane areas were as you would expect harder. I used either the bulb or wick or both. I'm going to try it again with my brother's mobo. Keep you posted.

oh, sry forgot to mention one more thing, sock puppet's advice to try pencil lead was interesting. You can poke the pencil lead (what do you call these in the states? mechanical pencils?) into a heated hole and the solder won't stick to the lead (graphite, correct?). Maybe if you get some lead the exact dia. of the hole, it might be possible to push the solder out. I had read of people using toothpicks and such to stick into lugs when they wanted to leave a hole to use later, but this probably works better since it seems to conduct heat better than wood(?).

[Brad1]

The site for bad motherboard caps:

http://www.badcaps.net/

I've changed out thousands of these in the past few years.
I start by simply heating the back side of the board cap-hole, then pulling the cap out. A lot of time, most of the solder will come out with it. Then I add a bit of new solder, and use a plastic Pull-it (sp) solder sucker. Occasionally, I'll have to turn the board over and do it on the other side, but most times it clears it all out. A trick I found on the plastic tip of those is to cut a small notch in the tip with snips just large enough to slip the tip of the iron in. I'll put the tip of the iron on the hole, put the sucker over it, and then let'er rip. By cutting that small notch, I found I could put the sucker on in a more upright position so it's circumference of the tip is more flush with the board. The tip solder is kind of filling up the notch, so it seems to provide a bit more sucking power, instead of the tip sucking a lot of air at an angle.

Brad1

[Mark Black]

Desoldering

I got one of these a while back:
http://www.mcminone.com/product.asp?...%5Fid=94%2D410

Because I couldn't afford $600 either. So far I'm pretty happy with it.

[Satamax]

Dai, i don't know what you like or anything else, but when working on double sided pcb, if i have to desolder, i put the board vertical ina vice or something (holds of some kind or another, like a 2X4 with a saw cut in it) desolder the part, put the nose of the desoldering pump (metal tube with a cylinder and a spring) on one side, and the soldering iron on the other, solder melted? I press on the knob to suck it out. That's what worked best for me so far. I use a weller 40 watter.