Desoldering on a PCB

[greengriff]

Hi All,

I've never worked on a PCB amp before and I've been asked by a friend to replace a knackered Cliff jack. It has 6 legs. My problem is I can't desolder it! I can never quite suck enough of the solder away to free all 6 joints and I'm afraid that if I hold the iron on any longer I will damage the board, which is cheap and thin.

Does anyone have any useful tips? I was thinking of using a dremel to cut the jack off since it is scrap anyway. That way I could then remove the legs individually. Any thoughts gratefully received.

[CraigW]

Are you using solder wick or vacuum to remove solder ??

[greengriff]

Vacuum (a solder sucker)

[CraigW]

I like to use vacuum on the larger items when possible, and finish up with wick. Sadly a low quality wick is not good. But you might try some if you have never used it.

[guitarmike2107]

I just replaced a similar cheap jack on a bugera. the solder sucker I had sucked badly, So I ended up breaking the plastic body and then removed the pins separately. Not a very professional approach, and there must be a better method but it got the job done .. just be gentle.

[greengriff]

Thanks!

[R.G.]

I just replaced a similar cheap jack on a bugera. the solder sucker I had sucked badly, So I ended up breaking the plastic body and then removed the pins separately. Not a very professional approach, and there must be a better method but it got the job done .. just be gentle.

Actually I consider it to be a very professional approach. In removing part from a board, there is always a chance of damage to the board or the part to be removed. If you have to salvage both the board and the part, it requires very careful work to remove the solder. It's much easier if you can decide that either the part you're removing or the board itself is expendable. If one of them can be trashed, do the trashing first and make it easier on the thing you're trying to save.

In this case, if you know the jack is bad, cut the legs off next to the body of the jack and then take the pins out one at a time. It's much gentler on the PCB you have to save. If you had to save the jack and could throw away the remains of the PCB, chuck the PCB in a vise, get out the propane torch and gently waft the heat from the flame onto the solder side while pulling gently on the part. When the hot air melts the solder, it will melt a circle an inch or two in diameter, and you can simply pull the part out when the solder lets go. It is possible to do this without destroying the PCB, but it takes a very, very gentle touch on the torch. This is the way that hot air rework tools work.

[greengriff]

A most helpful answer. Thank you.

[woodyc]

I find a Dremel tool with one of those thin discs really handy. It takes a sure hand and you need to wear glasses, but... here's a really easy way to get shorted bridges out of an old Marshall bass amp...

[jpfamps]

Lead-free solder on PCBs is much harder to remove than leaded solder.

I often resolder the joint adding leaded solder. This makes solder removal much easier.

Unless there is a very good reason to try to save the part being removed I always snip the old parts off the board before desoldering.

[TransLucid]

I've found that if, after removing as much solder as possible, you heat one pin and the wiggle the jack so it stays loose, then do the same with each other pin the jack will come out.

[R.G.]

I've found that if, after removing as much solder as possible, you heat one pin and the wiggle the jack so it stays loose, then do the same with each other pin the jack will come out.

That works if you have a good touch with a soldering iron. The danger is that the joint is stressed while it's hot. This can loosen copper from the PCB base material pretty fast too. I still do it, but I know the possible consequences. It's back at the decision about whether you can more afford to lose the part or the PCB. This is not a binary situation, in that it may work fine, but there is some chance the PCB traces will be damaged. It's a move in the direction of "save the part, not the PCB.

[jrfrond]

I get the sneaky suspicion that you are working on a double-sided PCB, in which case the only safe way to remove the jack without messing up the foil and plated-through holes would be to cut the leads and remove them individually.

Desoldering the many different types of available components properly is an art unto itself, and if you plan on doing mods and repairs, you need to arm yourself properly. At the very least, you need a good solder-sucker pump and good desolder braid. Look for the brands Edsyn and Chem-Wik respectively. Also, another valuable item is Chip-Quik. This is tin/bismuth alloy solder that you add (with flux) to the original solder joint, and it lowers the melting point of the solder to around 200 degrees F. As long as you keep all of the pins at this temperature, the component will lift right out of the board.

We have special desoldering units here in the shop that cost thousands of dollars, but the aforementioned items are what get the most use, and they aren't pricey.

[guitarmike2107]

I get the sneaky suspicion that you are working on a double-sided PCB, in which case the only safe way to remove the jack without messing up the foil and plated-through holes would be to cut the leads and remove them individually.

Desoldering the many different types of available components properly is an art unto itself, and if you plan on doing mods and repairs, you need to arm yourself properly

Yes I think it was double sided, it's gone now though, job well done, I felt like an amateur doing it, which I was, but since posting here I feel better about my “make do” methods.

I plan to stay an amateur at repairs, I don’t have enough time to build my own amp ideas as it is.

[km6xz]

ChipQuik or a real de-soldering/re-work station is the only professional ways of de-soldering. The part is not damaged which is needed since in pro work, the parts must be returned to the client. Vacuum pump type solder stations or hot air systems with proper flux can remove the part without damaging the pc board.
Pots, connectors and high thermal mass items soldered on 2-multi-layered ground planes of pc boards are very difficult to remove with only a soldering iron and a solder sucker or solder braid, but removals are fast and effortless with the right gear, or with Chip-Quik. If you take gear to shops, notice if they have at least a pro level de-soldering station and if not, find a more capable shop that is more respectful to your investment in your gear.