Desoldering Advice

C

comradehoser

Well-known member
I have a very stubborn 6-pin transformer that won't GTFO of my Neurocyton board.

I already had a Neurocyton board that sounded like ass, so I went at it again with a new board, put in the MMBF JFETS in ascending order of IDSS, took special care to solder everything correctly. Aaaaand, being a dummy, I desoldered the old transformer, which was a PITA, and installed it in the new pedal, having forgotten that I ordered a new one. Dead board, measured the transformer, and it's not reading continuity or resistance across any of the terminals.

So I want to take out the nonfunctional transformer and install the one that works, natch. Looks like I have successfully vacated the solder from 4 of the 6 terminals with my trusty Engineer solder sucker, but the last two are being extremely stubborn. I have already added solder and desoldered the trouble terminals twice.

I am very leery of lifting/destroying pads and traces and again ending up with a nonfunctional board so I'm currently out of ideas. The pins are too far apart for me to bridge them with the soldering iron. Maybe pressing the pins with a clothes iron set on the hottest setting? I have a heat gun I used for paint removal, but how do I not bake/char everything in the vicinity?

Advices?
 
If I don't need to reuse the component I just cut the legs and remove them 1 at a time. Not sure it thats a possibility here tho. Otherwise you could try gently pulling on the transformer while heating the legs and see if you can inch it out that way.
 
Superwick 425 desoldering braid is the key here. After you wick out most of the solder, press the pins over inside the solder pad hole with the soldering iron, then wick out the remnant solder. Should come out nicely.
 
When an Engineer solder sucker alone will not work I've had good luck with stainless steel desoldering needles.

1762367548839.png

I've broke quite a few though, I've yet to find a good quality set.

Basically you heat up the needle and it melts the solder, you press the needle so it covers the whole leg inside and through the pad. Remove heat, let the solder become solid, the solder does not stick to the needle.
 
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Thanks, folks!

Will try your suggestions--I forgot I have desoldering braid, will give it a go.

Desoldering needles is a first for me!

Dovetails--I totally would have gone the snipping route, but the transformer body is sitting right over everything. I'd have to destroy it and knowing me, probably would eff up the board pretty well. The legs are quite rigid, so inching it out is a lot more difficult than with other more compliant components.
 
Hal Harvey said:
When an Engineer solder sucker alone will not work I've had good luck with stainless steel desoldering needles.

View attachment 105790

I've broke quite a few though, I've yet to find a good quality set.

Basically you heat up the needle and it melts the solder, you press the needle so it covers the whole leg inside and through the pad. Remove heat, let the solder become solid, the solder does not stick to the needle.
Click to expand...
These have saved me a few times (and they do break easily). They cost a buck at Tayda, well worth it.
 
I use braid for most things.

Also have a plug-in solder sucker (nothing fancy, just a $30 one from EBay). Being able to heat and suck with one device is definitely easier/more effective for me.
**insert “that’s what she said” and rimshots as needed…;)

Chip Quik might be overkill for what you’re trying to do, but it’s a good thing to know about, if you don’t already:
 
comradehoser said:
I have a very stubborn 6-pin transformer that won't GTFO of my Neurocyton board.

I already had a Neurocyton board that sounded like ass, so I went at it again with a new board, put in the MMBF JFETS in ascending order of IDSS, took special care to solder everything correctly. Aaaaand, being a dummy, I desoldered the old transformer, which was a PITA, and installed it in the new pedal, having forgotten that I ordered a new one. Dead board, measured the transformer, and it's not reading continuity or resistance across any of the terminals.

So I want to take out the nonfunctional transformer and install the one that works, natch. Looks like I have successfully vacated the solder from 4 of the 6 terminals with my trusty Engineer solder sucker, but the last two are being extremely stubborn. I have already added solder and desoldered the trouble terminals twice.

I am very leery of lifting/destroying pads and traces and again ending up with a nonfunctional board so I'm currently out of ideas. The pins are too far apart for me to bridge them with the soldering iron. Maybe pressing the pins with a clothes iron set on the hottest setting? I have a heat gun I used for paint removal, but how do I not bake/char everything in the vicinity?

Advices?
Click to expand...
On those two stubborn pins that don't seem to clear out with the solder sucker, try putting a dab of fresh solder on them and allow it enough heat to melt and mix into the pad then try the solder sucker again.
 
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