Board DPDT desoldering

[potul]

Hi Folks

I recently bought a nice used TC Electronic Alter Ego for a low price due to the fact that the switch is not working properly. After looking at it, it seems like the old owner had the switch replaced at a local reapair shop (he confirmed this), but they used the wrong type of switch. They used a latching DPDT instead of a momentary, so now you need to double-tap each time... Not a pain for home use, but for live use I want this to be fixed.

So, I've already ordered a replacement switch (ALPHA momentary DPDT) that will fit. My only concern is that being the switch soldered to the double sided digital PCB, it might be a pain to remove it without damaging anything else. I had to remove once a 3PDT from my own PCB and it was really a PITA.
The switch looks like this one (not my picture, in fact it's another TC pedal, but it's quite the same layout):


So, any advice on how to remove it minimizing que risk? I have a solder pump and a couple of soldering irons, one of them with a power knob.
-Is it better to use more power so that the solder heat up quickly? Or low power not to damage other components?
-Should I go one pin by one, and let the pcb to cool down in between?
-Should I "destroy" the old switch instead?

BTW, the pedal is a nice delay, lots of features and good sounding. You can even load in your customized tones.

[JustinFun]

I wouldn't try it with a solder pump, I'd get some desoldering braid instead - it seems to work much better for me in completely clearing solder from joints.

Maybe my technique with the solder pump just isn't that good, but i only seem to be able to use it to remove huge gobs of solder, not to clear it off completely

[potul]

I agree that with the pump it's not easy to get all the solder out. It's great for big quantities though.
I have some desoldering braid as well, but I've never been successful with it. It might be a technique issue from my side....

This is the type of pump I own:

[lars-musik]

I recently bougtht this:

http://www.ebay.com/itm/ZD-915-Desoldering-Station-Iron-Gun-230V-130W-/291935511733?hash=item43f8b664b5:g:beIAAOSwImRYH4iI

for 80 Euros in Ebay Germany and couldn't be happier. Life is much easier.

[MrStab]

something i find helps from time to time is actually applying fresh solder to a joint then using the pump. helps if you get to a point where the solder's filling the hole itself but not sticking out from it, making it difficult to get the iron on.

for some reason, the desoldering pump is my fiancée's favourite tool of mine. well, second.

[armillary]

The desoldering station that lars-musik recommends is professional quality and likely the best solution.

But this will also do the job if you're on a budget:
http://www.ebay.com/itm/110V-115V-120V-40W-Electric-Desoldering-Iron-Pump-Vacuum-Solder-Sucker-40-watt-/191451729121?hash=item2c93698ce1:g:cOsAAOSwEeFVKiYK

It is a low quality 40W soldering iron with a hollow tip, combined with a low quality plastic solder sucker. It takes about 5 minutes to heat up to working temperature. You tin the tip for good conduction, push the plunger in to blow out any melted solder from inside the tip, an press it against what you want to desolder. After 15 or 20 seconds, press the button and see how much it sucked up. It will take several repeats per joint to get all, but it will get it all because the heat is still being applied when the suction is activated. The tip wears out quick, but I see the seller says he has more tips.     

I used this to remove four of six 11-pin SIP voice chips from a Juno synth without having to bend or cut any of the pins in the process.         
     

[potul]

Thanks for all the tips

The professional desoldering stations are out of question in my case. Not worth the investment.

I might get one of the cheap ebay desoldering irons. Are they really an improvement compared to an iron+pump? I suppose you eliminate the timing hassle of removing tip and pumping as quick as possible.

Is it better to use high or low temperature? In this case it's a through hole component in a double sided pcb.

Is chipquik an option as well?

[JerS]

On these types of switches, if you can get in and cut the pins at the switch - then remove them one by one with tweezers and a hot iron (pull from the switch side so you dont lift the traces). Go back with desolder pump to clear the holes out after pins are removed. It is slower - but minimizes risk to the pcb.

Cheers - Jeremy

[davent]

I had solder sucker like Potul posted but bought one of these with a silicone hose tip. Works far better, very powerful suction and tiny in size. Bought mine from Adafruit. I use it in conjunction with solder braid to do a thorough clean up. Solder sucker removes large quantities of solder quickly, important, less heating, less risk of lifting a solder pad.

https://www.adafruit.com/products/1597



dave

[Tony Forestiere]

Never had much luck with desoldering braid. I file a small, round notch in the sucker's tip about two-thirds of the iron's tip circumference. Heat the joint, apply the sucker with a good seal around the tip of the iron with the notch, push the button, lift both, and "Hey Presto".

[potul]

Well, good news is that finally I got my pedal repaired.

Bad news is that I definitively failed to desolder the DPDT nicely. After several atemps using the "heat and pull" method, I decided to give up as I was scared to damage the pcb with the heat. I did create a blob of solder to heat all pins at the same time, but I did not succeed to melt all solder at the same time to be able to pull the switch nicely.
At last I decided to "destroy" the switch (it was not good anyway), and desolder each pin separately. It took some time and I damaged one pad, but I was lucky and the pad was redundant (in fact, the pedal needs only a momentary spst, but it uses a dpdt, so only 2 pins are really doing something)
After this, I added more solder and used the pump to clear the holes.

It took me like one hour to remove the old switch, and 2 minutes to add the new one. 

Now I have a fully functional Alter Ego! I don't like the switch strong "click", but I will get used to it.

Thanks for the help everyone!

Mat

[armillary]

All's well that ends well!

[Rob Strand]

FWIW, I posted this link the other day on soldering:
http://www.diystompboxes.com/smfforum/index.php?topic=116543.0

The repair part has got a heap of info about desoldering and the pros and cons of each of the methods.
Some jobs require equipment no one will ever have at home but at least you can get the idea or what to look for.

[MonarchMD]

I will say that I've found not all desoldering braids/wicks to be equal. TENMA brand works best for me. I've used some off brand stuff off the shelf at the local micro center and just can't seem to pick up any solder with it no matter what temp I set my station to. Switches are the worst though if they're the big lugs with globs and globs of solder on the PCB.


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