Advice on Desoldering C64 Components

[toneburst]

What's the best method for desoldering components from the C64 circuitboard? I'm trying to remove the main power switch and 7-pin DIN power socket, but my desoldering pump doesn't seem to be doing the job, particularly on the larger blobs of solder nearest the edge of the board. Any advice gratefully accepted.

Alex

http://www.toneburst.net

[MRE]

multipin components are generally hard to take off. I usually work slowly back and forth with the pump or solder wick.

While heating one pin, push firmly with your thumb with the part. The idea is to 'wiggle' the part of, back and forth, by melting alternate ends of the part.

The other tip would be to remove as much solder as you can, then hit it with a hot air gun or torch. Obviously with the torch, you burn the board.

[Therezin]

The way I managed it was with a serious amount of desoldering braid and a 30W iron. The trick I found was to try to soak up all the solder around each pin, as best as possible - then try and lift it with a screwdriver.

[Wilba]

yeah, I had a similar experience - used a desoldering pump to suck up as much as possible... once you've got no solder blobs on the pads (i.e. you can see the hole) then wiggle the part while heating up the pins. Often you have to heat up two or more pins simultaneously to get it to move at all.

[Mr modnaR]

.....which is where a soldering fork comes in handy!  ;D

[stryd_one]

Hey Wilba what about the clothes iron or skillet things we looked at a while back... actually I think the skillet was for reflow soldering but I'm sure I saw an iron used as a desoldering platform of sorts? Can't find the link now of course  ::)

[c0nsumer]

I find that using braid to soak up most of the solder works great, then I center each pin in the hole using the tip of the iron. Usually after this everything is no longer physically secured and I can lift the IC straight out with very minimal effort. I've done DIP40 this way before without problem.

[Jidis]

As weird as it sounds, it also helps sometimes to actually resolder a particularly troublesome pin. I found that tip on the web or usenet a while back, and it's worked well on many occasions. On joints where you've managed to get most of the solder out, but there's a bunch around the inside edges of the hole, it merges into the old stuff and then the pump or bulb can make one big clean suck to get it all out.

BTW- I like that spring loaded pump tool with the latching button much better than the bulbs I've got, but they all get clogged too quickly. >:(

Take Care

PS- I "torched" a board with propane once, after reading about it. Nothing dropped out. The board just turned crispy and black with all the components still seated. :o

[MRE]

yeah for fun I tried torching a board after this post... what a waste!  hehe

another idea:  you need quick hands to do it, but I have had success with melting the solder one pin at a time and then while keeping the tip on the pin, hitting it with a quick strong burst of air. I usually blow on the hole from the component side of the board with the iron tip on the solder side.

You could also attempt to blow on it with a quick shot of compressed air.

Obviously, you need to pay attention to the blow out area.. IE where is that bubble of hot solder going to fly out too?

[toneburst]

All this is good advice. Thanks guys. I managed to unsolder that stubborn switch in the end by using the desoldering pump to get rid of as much solder as possible, the using a pair of pliers to gently waggle prise the pins away from the pcb from the component side, while heating them from the solder side. I broke the first one trying to do the same thing the 1st time, but this time I was a bit more careful and managed to get the thing off intact on the 2nd attempt.

Cheers again guys,

Alex

http://www.toneburst.net

[Steven_C]

I find that using braid to soak up most of the solder works great, then I center each pin in the hole using the tip of the iron. Usually after this everything is no longer physically secured and I can lift the IC straight out with very minimal effort. I've done DIP40 this way before without problem.

As weird as it sounds, it also helps sometimes to actually resolder a particularly troublesome pin. I found that tip on the web or usenet a while back, and it's worked well on many occasions. On joints where you've managed to get most of the solder out, but there's a bunch around the inside edges of the hole, it merges into the old stuff and then the pump or bulb can make one big clean suck to get it all out.

As a full time technician,  I recommend both these approaches, just remember to be patient, come back to it a few minutes later if you are risking overheating the component that you want to re-use. I think that the compressed air is a bad idea, for safety and the thermal shock can't do the internal wiring to the silicon any good on IC's.

sometimes you may have to wiggle a bit, this is usually only double sided boards with really tight pins.

On poor quality boards the tracks can lift easily  :o

A little secret I discovered... to remove a chip that is already dead, snip the pins off with a pair of side cutters, then just use the vacuum sucker to remove the solder and individual pins in one suck! But don't do this to your working SID's!

Steve

[c0nsumer]

A little secret I discovered... to remove a chip that is already dead, snip the pins off with a pair of side cutters, then just use the vacuum sucker to remove the solder and individual pins in one suck! But don't do this to your working SID's!

This is definitely the best way. Almost any part is easier to remove if you somehow cut it down to individually removable parts. Resistors, caps, whatever. Desoldering a single pin from anything is trivial.

-Steve

[MRE]

Well... yeah.. if you want to get rid of a bad part just snip it off! I do that all the time to repair boards.. but the topic was recovering parts from one device to use in another.  When you dont care about the part, its easy ;)

As to the air trick... I havnt used a can of air yet.. I have only done this method with a brisk puff from my own lungs. It sort of my last ditch effort, when the wick and the pump didn't do the job. Or putting a fat glob on the pin and then sucking it all back out didnt let it loose. It does work quite well.

The repeated heating from the iron is far more dangerous to the part than a brisk blow of air, even if it were cold air.

[DrBunsen]

Anyone had success with the hot air gun?  The toaster oven?

[MRE]

heh.. havn't tried either one. It was the hot air gun idea that got me thinking about the torch.. which we all know what happens with that one!

The hot air gun method was demonstrated on Hackaday.com a while back though.

Would think the toaster method would be a bad idea as it somewhat evenly heats the entire board, and chips. You want to heat the pins yet keep the chip itself as cool as possible. To get the all the pins hot enough to melt the solder enough to pull it up via a toaster, would mean the whole chip (delicate silicone transistors included) up to the same temp.  sounds like a bad idea to me..