Lead-free thru-hole repairs - techniques?

Discussion in 'Radio Circuits, Repair & Performance' started by KC8QVO, Dec 9, 2019.

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  1. VE3CGA

    VE3CGA XML Subscriber QRZ Page

    Like mentioned, you should try and get a vacuum desoldering tool.
    I have used a pace desoldering station for years, they are expensive but are the best.
    Perhaps someone locally to you has one to desolder that.
    The other suggestion would be a EDSYN SoldaPullet. I normally use one to desolder parts.
    You resolder the joint first with a bit extra solder, then reheat and when the solder reflows, press the trigger and it will usually suck the solder out.
    [​IMG]
    There used to be an antistatic version called the Silverstat that was more expensiveall .
    Amazon has these as does newark.
    https://www.edsyn.com/category/DHT.html
    https://canada.newark.com/edsyn/ds017/desoldering-gun-standard/dp/68C9589?MER=sy-me-pd-mi-alte
    https://www.amazon.ca/Edsyn-Deluxe-Soldapullt-Heavy-Vacuum

    Dont get the smaller pocket sized tools, they dont have near the vacuum this does.
    Just need to keep the white tip off hot soldering tips, it will melt after a while - handles molten solder but not a hot tip
     
  2. KC8QVO

    KC8QVO Ham Member QRZ Page

    I have had my eyes on one of these stations since I was in college. Just has never been "in the cards", but I am always reminded of how much nicer life would be when I get in to a project...
    https://www.paceworldwide.com/produ...t-350-multichannel-solder-desolder-and-rework

    As to the hand pieces and tips - not sure on the right combination just yet. But -they can always be upgraded. I'd say the iron, conventional desoldering iron (for axial/thru-hole components), and tweezers maybe with a couple tip sizes for SMT resistors, diodes, caps, and chokes would be a good starting point. Maybe when I can swing $1500-2000 on a set up it will come together...

    We used the big stations in college, something similar to the PRC-2000's, but probably a much older generation. Good stuff.

    A buddy of mine has a rework station and it looks like tomorrow will work for getting things knocked out. So that's what I am going to do.
     
  3. VE3CGA

    VE3CGA XML Subscriber QRZ Page

    yes they are quite the system
    I used them quite a bit when I was a Master Tech for 3M Canada, we used the soldapullet for less critical systems
     
  4. KD0CAC

    KD0CAC Ham Member QRZ Page

    I did the filters on an 897 maybe within the last yr.
    And used on of these JBC CS-E1 https://www.tequipment.net/JBC/CS-1...is3khM6Tt56fE1XrJTLFqi88KqsI5S1xoCt78QAvD_BwE

    Sure they can cost a lot $1,300 +
    But do some shopping , I found mine on eBay after shopping for multiple brands & models for at least 6 months .
    Found it and watched the bidding , people nickeled & dime'd literally , bidding was going up $3-$5 and was under a hundred dollars ,
    this was brand new in box & a service kits - cleaning & 3 sizes of tips in bags of 5 ea.
    I got pissed off on the cheap bidding and put a bid for $450 including shipping .
    Went back to see what it sold for , could not find the sale ?
    About 3-5 days later I got an email from eBay 2n chance - the seller said I could have at my bid .
    Didn't have the money , kinda , had to go through all my coin stash & rob a couple of other stashes scrapping together and now have a great desoldering station .

    You have to have enough heat , no mater what .
    Pre-heating to below any damaging , melting temp. , then apply other [ hot enough ] soldering tool , to blend other solders like either Chip-Quick or leaded etc.
    If you get good temp. controlled soldering iron , $75 - $150 Hakko , and then one of the manual solder-suckers , should work just fine , just more labor .
     
    Last edited: Dec 10, 2019
    KC8QVO likes this.
  5. AA3EE

    AA3EE Ham Member QRZ Page

    I've replaced those filters in a handful of radios. It's almost impossible without a vacuum desoldering tool. The problem isn't the lead free solder, it's the (relatively) enormous heat sink created by the PTH. That is typical for any PTH removal, but this problem is compounded by the large internal pieces of the filter that suck the heat away from the joint. Braid only works when you can maintain capillary action, it's very difficult to heat the whole solder slug and the wick with a standard iron. If you really want to do it yourself, cut the filter open, cut the plates apart and remove it in pieces.
     
  6. KC8QVO

    KC8QVO Ham Member QRZ Page

    The filters will come out tonight...
     
  7. KC8QVO

    KC8QVO Ham Member QRZ Page

    I forgot to post an update to this...

    The rig is back on the air and the receiver is like new again.

    The bad news -

    The filters are a REAL PITA to get out. It took 2 people working on the board - myself and a buddy. We were not able to get the solder to flow well. We used a vacuum desoldering iron that goes up to about 800deg at the tip. Most of the solder came out of the thru-holes, but not enough to get the legs of the filters loose.

    We ended up using the tip of the desoldering iron as an iron (stand alone iron wouldn't get hot enough) to loosen the solder on each pin. The filters were very early in the dissection completely destroyed. What was left was the bottom bakelite (or what ever the base material is) with the pins sticking through the board.

    Using a pick kit of multiple picks and pry tools we pulled each leg individually breaking the bakelite filter base and heating the pin on the other side of the board.

    It was a lot of work and time consuming. It also does not sound like a very delicate process, but we were as delicate as we could be given the circumstances.

    I did dislodge a smt cap when I was working the solder wick. It was microscopic so I taped it to a piece of paper so I wouldn't loose it.

    Once the filters were removed opening up the holes was another chore... I used an old resistor lead and the desolering iron and kept working at it.

    I ordered several replacement parts from Yaesu. They did not have .01uF caps in stock, however, so I don't have any for the DC block mod. I was going to use some axial lead .01uF's I have in my parts bins. Even though the ones I have are actually pretty small, after doing the board work I second-guessed the idea of using them as I don't want to hang the parts off the tiny traces. It just doesn't sound like a good idea. So I will try to get some proper SMT caps from another vendor.

    The order from Yaesu took about 2 weeks to get here. The shipment got lost in IL for a week or more of that.

    On the install side - I used 60/40 solder. It does not mix well with the stuff on the board. The reinstall of the smt cap was tedious but it went. I have various tweezers in my rework kit and made do. All my irons are standard irons, though, no heated tweezers.

    In the end, the repair has still been a success and the radio works great!

    I did the math on it and this radio was out of commission for 7 years. I set it aside as a repair project and never got around to it. I can't believe its been that long... but its fixed and on the air again now. This and getting my K2 finished up (loose phrase - not sure if this radio will ever be "finished") from a build I started in 2010 was my "Christmas present" to myself. Next up on the K2 is a built-in single port USB interface for digital modes (true PTT keying and sound card interface all "under the hood").
     
    Last edited: Dec 31, 2019
    N1OOQ likes this.
  8. AA3EE

    AA3EE Ham Member QRZ Page

    Good luck with the DC block mod. The 0402 caps must be perfectly centered on the traces. I used silver plated 30 AWG Kapton wire for the jumper. Solders easily and it's hard to melt the insulation.
    upload_2019-12-31_19-28-45.png
     
    KD2ACO likes this.
  9. KL7AJ

    KL7AJ XML Subscriber QRZ Page

    Whoever invented lead free solder is a moldy loincloth.
     
    KE8IWM, KC8QVO and NE4EB like this.
  10. KE8IWM

    KE8IWM Ham Member QRZ Page

    "The piston type of 'solder suckers' are sort of clumsy and have a habit of spraying solder 'dust' back onto the workpiece so you have to be careful."

    At my job, I won't allow those things in my department. Too often I've seen operators use excessive heat with an iron and the rebound when the spring is released drives the tool into the pad, pulling the pad and trace.
     
    KD2ACO likes this.

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