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Difficult recapping

S

Svein

pfm Member
I have tried to replace the small old 33uf capacitors on a spare DPA Enlightenment dac. I find it difficult to remove them, and just as difficult to get the new(Rubicon ZLH or Panasonic FC - both 47uf) in place. Any good tips?

vI9cBeo.jpg
 
You could try wobbling them until they fall off the board....then unsolder the leads that are left in the holes...then run a 1mm drill though the holes before popping in the new cap
 
That but be careful - old pcb tracks like these can lift easily, esp when heated a while / parts wiggled: , leaving with you with a botch to fix.

These are not glued in place; so should come out cleanly & easily.

Are you using enough heat - what power iron are you using, and do you have the bit cleaned & tinned for the desolder job / solderwick or a pump to remove excess solder from the joints...?
 
Mynamemynaim said:
You could try wobbling them until they fall off the board....then unsolder the leads that are left in the holes...then run a 1mm drill though the holes before popping in the new cap
Click to expand...

NOOOOOO!!!!! Don't put a drill through the plated through holes, severing the connection between top and bottom tracks on the board and vastly lessening the chances of the solder "wicking through" and repairing the connection.

Use a good hot iron and melt the solder on one lead whilst bending the cap back in the other direction, levering the lead with the now molten solder about halfway out. You won't have the space to take the first lead out fully before the caps body is levering against the PCB. Repeat for other lead but now take it right out then go back to first lead and fully remove this. This should remove the most awkward of caps from a double sided PTH board without damaging the PCB. now use a solder sucker to clear the holes. Adding more fresh solder can sometimes help at this stage as the overheated old solder can in effect form a "dry joint" in the hole and be more difficult to remove than a larger quantity of new solder and/or can leave a "partial hole" there that spoils the vacuum effect of the solder sucker.
 
I'd 'walk them out' as Jez suggests above. Don't be afraid of adding fresh solder, it'll help. Don't use lead free solder.
 
Gervais Cote said:
And use this vacuum pump if you want to make sure you remove all the soldering :

http://rover.ebay.com/rover/1/711-5...0001&campid=5338728743&icep_item=252020539494

The silicone tip of this sucker can touch the tip of the soldering iron so this seals the portion to be removed and greatly increases the efficiency.
Click to expand...

That looks like a really bad design, if you let it go whilst the end is near your eye it might cost you more than tears. Try this one, it’s cheap, it works.

https://se.rs-online.com/web/p/desoldering-reworking-tools/4794197/
 
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Arkless Electronics said:
NOOOOOO!!!!! Don't put a drill through the plated through holes, severing the connection between top and bottom tracks on the board and vastly lessening the chances of the solder "wicking through" and repairing the connection.

Use a good hot iron and melt the solder on one lead whilst bending the cap back in the other direction, levering the lead with the now molten solder about halfway out. You won't have the space to take the first lead out fully before the caps body is levering against the PCB. Repeat for other lead but now take it right out then go back to first lead and fully remove this. This should remove the most awkward of caps from a double sided PTH board without damaging the PCB. now use a solder sucker to clear the holes. Adding more fresh solder can sometimes help at this stage as the overheated old solder can in effect form a "dry joint" in the hole and be more difficult to remove than a larger quantity of new solder and/or can leave a "partial hole" there that spoils the vacuum effect of the solder sucker.
Click to expand...
For once, we are in complete agreement.

Regarding solder suckers, the best way I've found for cleaning holes is adding some fresh solder, then heat with the iron on one side of the board while sucking from the other.

Of course, cleaning holes wouldn't be necessary if everybody had the decency to use SMD parts whenever reasonable.
 
I never use a sucker, I walk parts out, add liquid flux then blow them through with a straw.
 
mansr said:
For once, we are in complete agreement.

Regarding solder suckers, the best way I've found for cleaning holes is adding some fresh solder, then heat with the iron on one side of the board while sucking from the other.

Of course, cleaning holes wouldn't be necessary if everybody had the decency to use SMD parts whenever reasonable.
Click to expand...

Oh we often are in agreement... for the other times keep reading my posts and learn grasshopper:D You may eventually understand the folly of SMD:) Great for laptops. Not so good for hi fi.

On a more serious note it's good to have another EE join me in the fight against fake news with the types that if they aren't shilling foo fuses are probably on a QAnon site!:)
 
Mynamemynaim said:
You could try wobbling them until they fall off the board....then unsolder the leads that are left in the holes...then run a 1mm drill though the holes before popping in the new cap
Click to expand...
Oh no, don’t do that. I aways use unsoldering braid.
 
mansr said:
What sort of machine are you referring to?
Click to expand...

Electric suction pump, temp regulated "gun" with hollow tip that sucks up solder, trigger on gun that operates pump... Mines a cheap Chinese one but works great. I toyed with the idea of a hot air gun to go with it but I don't do enough SMD really...
 
Arkless Electronics said:
Electric suction pump, temp regulated "gun" with hollow tip that sucks up solder, trigger on gun that operates pump... Mines a cheap Chinese one but works great. I toyed with the idea of a hot air gun to go with it but I don't do enough SMD really...
Click to expand...
I had a suction iron, pedal-operated, as a kid. Very useful for salvaging parts.

Nowadays I work mostly with SMD, and the hot air station is very useful indeed.
 
I’ve got a Hakko 301 (Amazon). An amazing thing that just takes do much of the risk away. I can’t remember where I got it from, somewhere in the EU rather than UK, but certainly shopping around can get the price down a good bit. I figured it will hopefully last me for the rest of my life and I can now pull old vintage 8 bit computer memory chips, DIL CPUs etc with it (just a nightmare with braid or an old-style sucker) with next to no risk of lifting tracks. Obviously great for audio too, especially the fragile boards in old Quad gear etc. I’m actually not bad at desoldering conventionally, e.g. I rebuilt my ZX Spectrum with just a sucker and braid and they have pretty naff quality boards, but this thing makes it so much easier!
 
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