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Thread: OT - How to Solder Circuit Boards

  1. #1
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    Default OT - How to Solder Circuit Boards

    I marked this OT because it is in regard to the wife's minivan. Her vehicle has a defect in the circuit board that controls the heat and A/C systems. Believe it or not there are actually 2 webpages out there devoted to troubleshooting the Nissan Quest / Mercury Villager minvans! It seems that the current draw of the rear blower motor overwhelms the board and the following occurs:

    "A little more info on this topic from a circuit board design point of view. Based upon the great photos, it is apparent that the cause of the failure of the circuit is the inadequate size of the circuit board trace from the landing pads of the 8 GA wires to the relay terminals. The + terminal is broken and happens to be the smaller of the two traces. The large current draw is overheating the copper trace and it loosens from the circuit board substrate - well you know the rest."



    So, they recommend the following:

    "A better remedy to this situation is to increase the effective conductor size to the relay by placing a short jumper between the landing pads of the 8 GA. wire and the relay terminal on the underside of the board. This will give the current an alternate parallel path and reduce heating because of an overall larger equivalent conductor size. Simply resoldering the board will remedy the problem only if a lot of solder is used and bridges the conductive path to the relay and landing pads. A better solution would be to install these jumpers to increase conductor size."



    My question is how do I make this repair? Does the copper wire have to touch the board or can I lay down a puddle of solder and then stick the wire in it and throw down some more solder to secure it? Any recommendations on wire or solder type? I have a soldering gun and 2 types of solder (high and low melting temps) but only have experience with soldering wires together.
    1978 CJ-7 AMC 360, TH400, Quadratrac with low range and manual shift, 4.10 gears, Superior Axles, Lunchboxes F&R

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  2. #2
    Registered ChiliPepperTJ's Avatar
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    I've soldered circuit boards before. You can either get your soldering iron and take the solder out of the hole that is in the board already, place the 8ga wire through both holes and then solder around where they go through the board, the solder will flow through (that is if the wire and whetever comes through from the other side of the board will fit in the hole together). The other option is to clean the surface of the board that you are going to solder onto with an exacto knife. Take the coating over the copper down until the copper comes through,(you may want to rough the copper up lightly with a fine piece of sandpaper or emerycloth to give the solder something to adhere too) then lay your 8ga jumper over it and solder it on. Be careful of the board though, they are delicate. Use resin core solder too it works well. Make sure you get a good hot joint so it won't come off when it cools. Hope this helps.
    Good luck,
    Kevin
    '84 CJ-7 Renegade- 258 GM TBI with spark control and HEI, t-5, d300, d30 w/aussie locker, amc20 w/ trac loc, 33" Swamper SSR's, 2.5" BDS, 1" BL, MORE shackles, Superwinch hubs, Superior shafts, tie-rod flip, Taurus Fan, YJ brake booster, Full cage, A to Z rocker guards, A to Z rear cage, lots of other stuff...
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  3. #3
    JKer with CJ/FSJ blood Ken Gaines's Avatar
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    My opinion...don't touch the board with the iron. The heat from the tip could damage the board. Some of the components are very heat sensitive, so don't directly heat a component if you don't have to do so. Take great care NOT to pull on the components. I ruined a perfectly good board once by pulling on somenthing I shouldn't have pulled on and I pulled the circuit trace right off the board. To keep it Jeep-related here, I had to do some very precise soldering when I put the 28-pin flash ROM adapter in the ECM that powers my CJ's EFI engine. BEFH did some of the soldering too. That was the SECOND ECM I had because the first one was the one that I pulled the trace off the board due to stupidity and inattention to detail. For what you are doing, it seems that you could lay some solder at each point then re-melt it and lay the wire into it.
    Too bad you aren't a little closer. You could bring that board to me or BEFH and we could have it fixed in a jiffy.
    Originally stated by Mr.George Carlin -=-
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    You will need to take great care working on a heat damaged board. Clean the contact points with alcohol and a tooth brush first. You are going to need some Sn 60 solder 60/40 tin/lead. Dont use garage type solder ( big fat heavily cored stuff) Use no more than a 25 watt iron with a .125 tip. Reflow the solder at the contact points first but don't add any more new solder than necessary to get good heat transfer. Cut and shape your jumper wires. Tin the ends of the jumpers. Lay the jumper in place and touch the iron to it and the leg at the contact point. Add just enough solder to get a good shinney fill.( another case where the bigger the blob the better the job does not apply). The jumpers will only need to be soldered at the contact points. Clean the new solder joints with alcohol and the tooth brush again. You can used clear nail polish as a sealer if you want.
    Steve Keaveney 82 CJ5 258 T177 Howell TBI TFI/HEI ignition YJ 3.5" EZ ride lift M.O.R.E 1 1/4" BL 3/8" shackles JKS Discos Auburn Pro, TruTrac, 4.10's, 33's, FR shaft, Warn hubs, Warn 8274 and a bunch of other junk

  5. #5

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    Third reply above gives correct instructions.
    You can not just heat solder and drop the jumper into it.. This will result in a cold solder joint (which will give poor electrical contact, and won't hold mechanically.) The work itself (jumper and pin on circuit board) must be heated, and the solder melted by contact with the heated work.
    Note the above instructions about using a soldering IRON... Follow them! Your soldering gun is the equivalent of a BFH in regards to electronic circuits... It's too large a tool for a circuit board.

  6. #6
    JKer with CJ/FSJ blood Ken Gaines's Avatar
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    Once again, you come in here and blast people for trying to help. This is the second time you have done this to someone in what...a week? I guess the other two posts in the thread, in your infinite wisdom and glory, are completely wrong and have absolutely NO bearing on the subject matter at hand.
    Merry fawkin Christmas, Rocky. It sure is good to see that you are consistent in your ability to do one thing...insult others.
    Originally stated by Mr.George Carlin -=-
    You know what's the best thing about living on the edge of the water? You only have * * * * * * *s living on three sides of you. If they come from the other side, you can hear them splashing!!!
    "Life is a journey that's measured not in miles or years, but in experiences."
    -Jimmy Buffett 1998
    "If you don't fish, you should."
    -D.A. McKee Ph.D., 2002 TAMUCC Ichthyology Class Intro Lecture (How much more wisdom could one need than this?)
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    Ken

  7. #7

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    Don't take things so personally.
    You gave some mis-information. Someone else appears to have more knowledge and experience on the subject... Their advice was correct. The person asking the question deserves to have good advice, wouldn't you agree?

    Edit: BTW, I blasted nobody... Only pointed out correct and incorrect information.

  8. #8
    JKer with CJ/FSJ blood Ken Gaines's Avatar
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    Okay, tell me what was so wrong. Please. Let's see...
    ...don't touch the board with the iron. The heat from the tip could damage the board. Some of the components are very heat sensitive, so don't directly heat a component if you don't have to do so.
    I don't see anything wrong with THIS part. Hmmm...no mention of a soldering GUN here...just an IRON and the TIP. Please refresh my memory. Aren't electronic components sensitive to excessive HEAT??? Wait...didn't YOU just say to use an IRON and not a GUN? Yes...here it is..
    -= Originally posted by LilRocky =- Note the above instructions about using a soldering IRON... Follow them! Your soldering gun is the equivalent of a BFH in regards to electronic circuits... It's too large a tool for a circuit board.
    Take great care NOT to pull on the components. I ruined a perfectly good board once by pulling on somenthing I shouldn't have pulled on and I pulled the circuit trace right off the board.
    This part is relating a personal experience and what can happen if you DON'T pay attention to detail when soldering electronic components to a PC board. I don't see too much mis-information here. You live and you learn.

    For what you are doing, it seems that you could lay some solder at each point then re-melt it and lay the wire into it.
    So this is what you are saying is wrong. If you reheat the solder with the wire ON the joint while you are heating it, you WON'T get a cold solder joint.
    I guess nobody else here has ever soldered a circuit board before. I don't see very much mis-information here, Rocky. What I DO see is someone that needs to find a different approach to how he decides to point out what he believes to be erroneous information. Abrasive is a good word for it, man. Maybe you should remember that you aren't the only experienced person here...or maybe you could just take your holier-than-thou attitude over to Pirate where it would be welcomed...for a while before you piss them off too.
    Originally stated by Mr.George Carlin -=-
    You know what's the best thing about living on the edge of the water? You only have * * * * * * *s living on three sides of you. If they come from the other side, you can hear them splashing!!!
    "Life is a journey that's measured not in miles or years, but in experiences."
    -Jimmy Buffett 1998
    "If you don't fish, you should."
    -D.A. McKee Ph.D., 2002 TAMUCC Ichthyology Class Intro Lecture (How much more wisdom could one need than this?)
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    Ken

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    Thanks for the replies - I am going to take a shot at this later in the week.

    Merry Christmas!
    1978 CJ-7 AMC 360, TH400, Quadratrac with low range and manual shift, 4.10 gears, Superior Axles, Lunchboxes F&R

    1981 CJ-8 4.0L HO MFI TF999 Dana 300 Completely Restored 3.5" lift Full Hard Top

  10. #10
    Forum Leader John Strenk's Avatar
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    I like riskeacj5 idea but differ in the size of the iron. Like Ken says, don't try to heat the board. We want to by pass the board now. Like Chilli says, use a small dia. rosin core solder available at Radio Shack.

    I would get some solder wick or a solder sucker and remove all the solder around the contact. Clean the area with alcohol like riskeacj5 says

    Like LilRocky says, I would then form my jumper wire around the contacts clamping it securly to to contat points before adding any solder. If you have solder in between the jumper and the contact it may melt again from the current it has to pass and develope a bad, cold contact again.

    In my opinion the 25 watt iron would be to small. THe 8 gauge wire will act as a heat sink and you could end up reflowing the solder on both ends of the jumper. If you had soldered one end already you may create a cold solder connection on that end. I would use a big iron or gun and do it quickly.

    I would make sure the gun or iron is already fully heated. Dont but the gun on the jumper and pull the trigger or you'll end up heating the whole jumper before the solder will flow. Place the solder on the point were the jumper and contact touch on the inside of the bend. Place the gun/iron on the jumper wire on the outside of the bend. Only keep th heat on long enough for the solder to melt and wick up around the contact and jumper and remove the gun/iron. This sould only take a few seconds. Allow everything to cool and go onto the next connection.

    THe only problem with my way is if you apply heat to long you will be buying a new board. So you have two differnt ways to think of trying. Just be aware of the problems of both ways.

  11. #11
    Registered 80sCJ7's Avatar
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    If you're worried then use a junk remote control or radio etc. to practice on first. As has been said, the 8 ga. wire will act as a heat sink so use a hot iron/gun. Remove the relay from the socket first (if you can). Then you're only applying heat to an 8ga. wire and an empty socket so not much worry about destroying anything with heat.
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    You know, if you haven't already fixed this, and assuming your pics are of "your" circuit board, you might try just resoldering the connection you have a problem with. If it fails again, then go for the permanent patch. This would also depend on how long it took to fail the first time. My $.02...

    To me it looks like your solder joint broke possibly due to heat and combination of vibration or physical flexing, and not because your trace was undersized. As you can see in the pic, the relay connections are not folded over like the other mounted components before they are soldered. If any tension was on the relay legs when mounted (in/out), that would be the more of the cause, as it seems most of the original solder was intact.

    BUT,... if you find that your connections will not clean up well and won't hold solder or "tin" due to heat damage, then immediately go for the permanent patch. Your pic doesn't appear so. The patch wire used in your second pic seemed more of a heat sink than anything as the "repaired" board didn't even seem to have any heat damage.

    Again, just resoldering the original connection would be easiest/cheapest/fastest and hopefully will work out fine for you. BTW, try a search on "how to solder" for some detailed info. My $.02 and good luck on a cheap (and permanent) fix. -HTH
    -Geno '83 CJ-7; 'glassed, HEI'd, TBI'd, 2.5'd, MTR'd,.. and other repairs disguised as upgrades!

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