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General => Open Discussion => Topic started by: Beedoola on January 09, 2014, 01:54:27 AM

Title: Desoldering double sided PCBs
Post by: Beedoola on January 09, 2014, 01:54:27 AM
Anyone have any tips on how to desolder pots on a double sided PCB.

I'd taking apart a Wampler Faux Reverb to trace and it was a pain getting the Belton desoldered. I have a solder sucker and a desolder braid but both aren't totally effective - I can't completely remove the solder sometimes.

Any tips? Or am I using the brains wrong?
Title: Re: Desoldering double sided PCBs
Post by: pryde on January 09, 2014, 02:07:19 AM
I have the same trouble you do with a basic desoldering pump or braid. I just destroyed a pcb trying to desolder a belton brick from it.

I think the best option would be an electric type pump that will heat and suck solder at the same time. I don't have one but they should be more effective. Here is a cheap one that might work better:

http://www.amazon.com/ECG-J-045-DS-Watt-Desoldering-Iron/dp/B00068IJSG/ref=pd_sbs_indust_2
Title: Re: Desoldering double sided PCBs
Post by: gordo on January 09, 2014, 04:29:40 AM
Don't have an answer for you but one of the things that REALLY makes it a challenge with commercial boards is that with the advent of Lead-free solder your solder (and de-solder) temperatures are a good bit higher.  Bottom line is that double sided/plate thru boards were not designed to be redone...and for most manufacturers that's a good thing.
Title: Re: Desoldering double sided PCBs
Post by: Mich P on January 09, 2014, 08:15:04 AM
Hakko desoldering gun or some other professionnal tools is what you need for some proper job
but the price of them is quite high !!
Mich P.
Title: Re: Desoldering double sided PCBs
Post by: alanp on January 09, 2014, 08:29:55 AM
The more pins, the worse the job.

Rotary switches are completely not worth bothering with trying to de-solder. Don't ask how I know... blimmin' zero point...
Title: Re: Desoldering double sided PCBs
Post by: gtr2 on January 09, 2014, 11:41:34 AM
Hakko 808.  The only thing I don't like is how long I waited to get one  :D

It's paid for itself.

Josh
Title: Re: Desoldering double sided PCBs
Post by: LaceSensor on January 09, 2014, 11:46:10 AM
Quote from: alanp on January 09, 2014, 08:29:55 AM
The more pins, the worse the job.

Rotary switches are completely not worth bothering with trying to de-solder. Don't ask how I know... blimmin' zero point...
In the case of a rotary, assuming you can at least access the outer lugs, Id just use a small set of decent snips and cut them legs off.

Then, use some wiggle skills and gradually work the 3 or 4 centre pins free.
After that, solder suck the pins left in, and completely replace the switch.
It remains however a massive pain in the ass, and is the reason I used flying leads on my ZPSDX after I also managed to damage the rotary after it was soldered to the breakout board. For a $1.50 part and some extra wire, it just wasnt worth the effort.

Title: Re: Desoldering double sided PCBs
Post by: LaceSensor on January 09, 2014, 11:49:38 AM
Quote from: Beedoola on January 09, 2014, 01:54:27 AM
Anyone have any tips on how to desolder pots on a double sided PCB.

I'd taking apart a Wampler Faux Reverb to trace and it was a pain getting the Belton desoldered. I have a solder sucker and a desolder braid but both aren't totally effective - I can't completely remove the solder sometimes.

Any tips? Or am I using the brains wrong?

For most simple things like caps, resistors and diodes, I tend to just cut them and throw them away.
Its much easier to get the "leftover" legs out that try to desolder those peices intact.

Likewise for common 8/14/16 pin opamp style devices. Assuming you can replace it easily, I wouldnt bother saving it and just cut all the legs off.

As someone highlighted, ROHS solder is a pain, so even if you do what I recommend, when you come to try to solder such the leftoever legs or whatnot, add some 60/40 or whichever you use to the pad, it will make removing the solder much easier.


In the specific case of beltons, I think overheating the device would be a danger.
Therefore, if I really had to, I would cut the pins of that again, and do the same as above.
Upon reinstall, just tack solder some small extensions (from single core cable, or old resister legs etc)
Title: Re: Desoldering double sided PCBs
Post by: raulduke on January 09, 2014, 11:56:57 AM
I do the same for most components when desoldering; cut one of the legs, remove the component and legs and then desolder. Ruining one component is usually cheaper than destroying a pad on a board.

An blade solder tip, like below, is really helpful for removing PCB mount pots etc. I imagine it would be easy to remove a belton brick with the right width tip.

(http://uk.farnell.com/productimages/farnell/standard/42271373.jpg)
Title: Re: Desoldering double sided PCBs
Post by: pickdropper on January 09, 2014, 01:50:48 PM

Quote from: raulduke on January 09, 2014, 11:56:57 AM
I do the same for most components when desoldering; cut one of the legs, remove the component and legs and then desolder. Ruining one component is usually cheaper than destroying a pad on a board.

An blade solder tip, like below, is really helpful for removing PCB mount pots etc. I imagine it would be easy to remove a belton brick with the right width tip.

(http://uk.farnell.com/productimages/farnell/standard/42271373.jpg)

Yeah, I have dual blades on my OKI/Metcal tweezers and they work well for removing pots.
Title: Re: Desoldering double sided PCBs
Post by: Fastocker on January 09, 2014, 02:27:07 PM
Agreed -- the 808 is the best piece of pedal building equipment I've ever bought.  I giggled like a little school girl first time I used it.  I highly recommend this one to anyone doing a lot of building or tinkering.

Quote from: gtr2 on January 09, 2014, 11:41:34 AM
Hakko 808.  The only thing I don't like is how long I waited to get one  :D

It's paid for itself.

Josh
Title: Re: Desoldering double sided PCBs
Post by: culturejam on January 09, 2014, 02:53:56 PM
Quote from: Fastocker on January 09, 2014, 02:27:07 PM
Agreed -- the 808 is the best piece of pedal building equipment I've ever bought.  I giggled like a little school girl first time I used it.  I highly recommend this one to anyone doing a lot of building or tinkering.

Quote from: gtr2 on January 09, 2014, 11:41:34 AM
Hakko 808.  The only thing I don't like is how long I waited to get one  :D

It's paid for itself.

Josh

I'll third this. The 808 is magical.

But, you do have to maintain it. It needs to be cleaned regularly, and you have to change the filter, etc. The upside is that it was designed well, and replacement parts are readily available.
Title: Re: Desoldering double sided PCBs
Post by: playpunk on January 09, 2014, 08:03:52 PM
Have any of you guys used any of the clones available? The cheapies from Circuit Stations for instance?
Title: Re: Desoldering double sided PCBs
Post by: culturejam on January 09, 2014, 08:06:49 PM
You mean this one? http://www.circuitspecialists.com/csi474a.html

I almost bought that unit. I went with the Hakko 808 because it takes up less space on my cramped bench.

For the cash, it's very tempting.
Title: Re: Desoldering double sided PCBs
Post by: playpunk on January 10, 2014, 01:48:43 AM
Yeah. I wouldn't mind one of those to help clean up my mess ups.


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