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Yet another soldering question, desoldering.

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Yet another soldering question, desoldering.

Postby Dr R » Sun Feb 10, 2019 6:13 pm

Evening all,
I need to remove and reattach an Aux socket from our Yamaha mixer after a cheap jack plug broke while in there, leaving the tip loose between socket and the circuit board. It's proved impossible to get it out through the socket, so I have had to disassemble the mixer and remove the relevant board.
The offending tip is rattling between the board and the barrel of the connector, trapped by the pins. If I take off the socket then the tip can be removed in about 2s, and the socket soldered back. Plus an hour to then reassemble the desk of course.
Photographs of the socket with the tip inside, and the back side of the pcb are here:
https://m.imgur.com/a/OU0D1Cz

The question is, is there anything untoward I should be wary of before I desolder and resolder the connector? Other than being vary careful around those little surface-mount components?

As ever, many thanks for all the fantastic advice on this forum,

Rich
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Re: Yet another soldering question, desoldering.

Postby Wonks » Sun Feb 10, 2019 6:26 pm

Just remember that it will be lead-free solder that's used on the board, so you really need to use that to solder a new socket on. It's almost impossible to get all traces of the previous solder off, and lead and lead-free solder don't work together. And lead-free solder melts at a higher temperature than leaded solder, so the joint needs to get warmer for the solder to work.
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Re: Yet another soldering question, desoldering.

Postby fruitcake » Sun Feb 10, 2019 6:39 pm

I'm by no means an expert solderer,... but I'll clip on a heat sink if I'm anywhere near sensitive components. And I've found the desoldering tape to work fairly well.
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Re: Yet another soldering question, desoldering.

Postby scw » Sun Feb 10, 2019 7:15 pm

I use kapton tape to mask components that are close to the work area. Cheap and effective if there's a risk of damaging those nearby SMDs!
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Re: Yet another soldering question, desoldering.

Postby ef37a » Sun Feb 10, 2019 9:27 pm

I would strongly suggest you first get a replacement jack, they look pretty stock items.

Then, with some big pliers crunch the existing one until you are left with the pins in the PCB then heat those up individually and remove gently with tweezers.
I say this because I am pretty sure that is double sided print and it is very hard to desolder completely from one side in one go and you then run the risk of lifted print. Can all be fixed but messy.

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Re: Yet another soldering question, desoldering.

Postby Dr R » Sun Feb 10, 2019 9:51 pm

Thanks everyone, that's exactly the sort of advice that makes SoS so helpful. :thumbup:

Dave, I have the service manual and parts list for the mixer, so I can get a replacement socket it needs to be the right height as the board is held in place both by screws on the board at the back and the nut on the front. I might be able to cut the socket rather than mangling it, will have a look.
Wonks - how do you know it's lead-free without knowing the model? I'm not doubting you, just amazed.
I've never used desoldering tape, only solder suckers, but I've usually done OK with them.
Scw- Never even heard of Kapton tape, but a quick google says it's a sort of insulating tape. Do you just make over the things you want to protect? And how do you use a clip-on heat sink?

So the plan is to source lead-free solder, kapton tape, the replacement socket, and if it all arrives by the weekend then I'll so the job then.
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Re: Yet another soldering question, desoldering.

Postby Wonks » Sun Feb 10, 2019 10:29 pm

Anything sold in the UK /EU since Aug 2004 has to use lead-free solder, and there was obviously kit before that date with it. So unless it's vintage kit, it's almost certainly going to use lead-free solder.

If it's got an RoHS logo on it, it's definitely lead-free.
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Re: Yet another soldering question, desoldering.

Postby Dr R » Sun Feb 10, 2019 10:52 pm

Wonks wrote:Anything sold in the UK /EU since Aug 2004 has to use lead-free solder, and there was obviously kit before that date with it. So unless it's vintage kit, it's almost certainly going to use lead-free solder.

If it's got an RoHS logo on it, it's definitely lead-free.
It's a Yamaha EMX 5016cf, which I think started in about 2007 and still seems to be made. So definitely lead free. :)
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Re: Yet another soldering question, desoldering.

Postby scw » Sun Feb 10, 2019 11:57 pm

Yes, just use the kapton tape like masking tape and mask over everything you want to protect. It's study on one side but doesn't leave a residue. It comes in various widths so buy one wide enough for your job.
A heat sink specifically clips onto any component that you don't want to overheat. It draws the best from the iron away and dissipates it.
One other thing I'd recommend getting is rosin flux. It's inexpensive and makes soldering much cleaner and easier IMO.
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Re: Yet another soldering question, desoldering.

Postby ef37a » Mon Feb 11, 2019 9:18 am

Dr R, I do not like suckers! they can lift print. The de soldering braid is slower (don't be mean with it!) but you stand far less chance of damaging anything. Some cocktail sticks are handy for cleaning holes. Do NOT be tempted to use copper wire.

Cannot see where you will need a heat shunt. I use one yonks ago for Germanium transistors, never since. Yes, tape down those SMT components! You will scream if they drop off but not as much as you will trying to put them back!

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Re: Yet another soldering question, desoldering.

Postby wireman » Mon Feb 11, 2019 9:06 pm

Wonks wrote:Anything sold in the UK /EU since Aug 2004 has to use lead-free solder, and there was obviously kit before that date with it. So unless it's vintage kit, it's almost certainly going to use lead-free solder.

If it's got an RoHS logo on it, it's definitely lead-free.

Feel free to read the regulation which has some exceptions.
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Re: Yet another soldering question, desoldering.

Postby Watchmaker » Mon Feb 11, 2019 10:10 pm

try a bit of sticky tape on the end of a forceps or something first :D

Desperate perhaps, but I'd try pushing out the side or extracting it through the barrel for awhile before heating up the gun
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Re: Yet another soldering question, desoldering.

Postby Folderol » Mon Feb 11, 2019 10:17 pm

The answer is to learn (and become adept with) as many different methods of solder/component removal as possible. There is no 'one size fits all'
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Re: Yet another soldering question, desoldering.

Postby Dr R » Mon Feb 11, 2019 11:05 pm

Watchmaker wrote:try a bit of sticky tape on the end of a forceps or something first :D

Desperate perhaps, but I'd try pushing out the side or extracting it through the barrel for awhile before heating up the gun

Yep, tried all that :-( I even bought some super-long-nosed tweezers which almost worked to get it out vertically, but not quite. I can't get the blighter past the spring connector. I thought I could get it out sideways between the pins once I had the board out, but it's just a bit too big, and I can't get the purchase to force it. It's been stuck since June, with various attempts over time, but I'd quite like fully working by Easter

I think I'll order the bits, inc desoldering braid, then have another concerted go at removing the thing mechanically this weekend. Hopefully the law of sod will work in my favour and I will have bought a bunch of stuff I didn't need, but won't have damaged anything. This week is a bit mad with paid employment, but I'll post any updates.

Many thanks all, as ever!

Rich
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Re: Yet another soldering question, desoldering.

Postby blinddrew » Mon Feb 11, 2019 11:14 pm

I like the idea of trying to turn sod's law to your advantage, good luck!

Two quick questions, are you able to move the tip around at all within the socket? Is it a tip with a hole where it was initially mounted or a stud?
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Re: Yet another soldering question, desoldering.

Postby Sam Spoons » Tue Feb 12, 2019 1:17 am

This happened to me once, the bugger is that I can't remember if or how I solved it, I can however remember that getting it out through the plug was impossible as, unless the tip was exactly aligned, nothing would induce it to pass through. It was a tip with a hole though, one with a stud would almost certainly have been possible to remove with the right size forceps.
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Re: Yet another soldering question, desoldering.

Postby scw » Tue Feb 12, 2019 2:36 am

Could you solder a piece of wire to the bottom of the broken tip and pull it out?
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Re: Yet another soldering question, desoldering.

Postby Watchmaker » Tue Feb 12, 2019 2:49 am

it's a dilly alright. a real skill builder. let us know the outcome :?:
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Re: Yet another soldering question, desoldering.

Postby MarkPAman » Tue Feb 12, 2019 2:48 pm

I've fixed this problem quite a few times, more often than not without any soldering or damage to the equipment involved.

I usually manage to grip the broken off end bit with a drill bit twisted into the centre of it
- by hand - get the correct sized bit and it will grip surprisingly well. Occasionally, I've had to use a drop of superglue too, though the drill bit is then junk.

Yours appears to have turned sidewise too, which may prevent this, but if you can get it the correct way up again, this is worth a try.
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Re: Yet another soldering question, desoldering.

Postby Martin Walker » Tue Feb 12, 2019 3:17 pm

Folderol wrote:The answer is to learn (and become adept with) as many different methods of solder/component removal as possible. There is no 'one size fits all'

Yep, that hits the spot Folderol - I've used a solder sucker, cutting component leads first before desoldering (easier to pull the remaining piece of wire out of its circuit board hole when there's nothing else attached to it).

I even have a supply of (bluntish) syringe needles for poking a hole in a circuit board where a component used to be, but which the solder sucker refuses to evacuate - place soldering iron on appropriate position, push the needle through when solder has melted, and then (because it's stainless steel) the needle can be easily pulled out again, leaving a neat hole ready to accept the replacement component's 'leg' ;)


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