Can you recommend a good vid for desoldering please? - Page 1
Forum section: electronics / beginners

author: HobGoblyn
author_rank: Unknown
timestamp: January 23, 2020, 04:33:52 pm
content: Have just tried to desolder a switch (from a towel rail timer) that seemed to have a ton of solder holding it in.It's not an important thing as in I've replaced the timer, it was more out of interest in seeing if I could see what was what.The way it was made is the spur switch on the front of the timer was soldered onto the PCB meaning I couldn't remove the PCB without desoldering the switch.I have a new Hakko FX888d, decent flux, MG solder wick and a desolder pump.First I tried with the Hakko on 350, didn't begin to melt the solder, then I tried at 450, it would melt, but took a good 5 - 10 seconds before it did so (this was straight onto the solder, not using the wick). I tried sucking it up, it got a lot, but left loads.I then tried the wick, both as it was, and with a bit of flux added. I still really really struggled, in the end I gave up.I've since watched a couple of vids that suggest putting leaded solder on first. I wondered if anyone could point me to a beginners desoldering guide vid? (I found good how to solder vids searching this forum)I also have a hot air station, I'm wondering whether I might have been better using that to get the board off of the switch?I've included 2 pics, first showing how bad my desoldering attempt is, second showing how much solder is on all the joints.many thanks

author: HobGoblyn
author_rank: Unknown
timestamp: January 23, 2020, 06:58:46 pm
content: Watching the Pace how to solder videos from the 80s, I suspect my main problem was too smaller tip. But any pointers much appreciated.

author: tautech
author_rank: Super Contributor
timestamp: January 23, 2020, 07:22:13 pm
content: Being proficient at soldering for repair work is prerequisite otherwise you can do more damage than you're trying to fix.Practice salvaging parts of old boards.Understand thermal mass and the tip sizes needed for good thermal transfer.Understand dwell times that are appropriate for a particular task. Often hotter and faster is best.Get a solder sucker for when joints have large quantities of solder to remove.Think of braid as a clean up tool only.Use leaded solder, none of that Pb free muck !Suckers will often pull the solder clean out of holes but occasionally you need new clean solder on the joint and suck it off again.

author: tester43
author_rank: Regular Contributor
timestamp: January 24, 2020, 03:36:50 pm
content: hours of fun with Louis Rossmann on youtube.He is resoldering parts of computers but you will get the point:1. no such thing as "too much flux" exists2. fresh solder applied also for cleaning3. solder removal pump is non-optional

author: tautech
author_rank: Super Contributor
timestamp: January 24, 2020, 08:43:31 pm
content: Quote from: tester43 on January 24, 2020, 03:36:50 pmThey are a valuable entry level tool for little outlay.Some are better than others.

author: mariush
author_rank: Super Contributor
timestamp: January 24, 2020, 09:03:23 pm
content: Liquid flux / paste flux helps. A LOT.It doesn't have to be 5-10$ flux pens with 5-10ml of flux. You can buy 50ml/100ml/500ml/1000ml bottles for 10-20$, here's just a couple examples100ml :https://www.tme.eu/ro/en/details/flux-tk_100/fluxes/ag-termopasty/art-agt-045/500ml :https://www.tme.eu/ro/en/details/flux-tk_500/fluxes/ag-termopasty/art-agt-075/100ml paste/gel :https://www.tme.eu/ro/en/details/topnik-zel_100/fluxes/ag-termopasty/art-agt-089/A lot of times it helps to ADD leaded solder to the joints that you want to desolder. Add leaded solder. It mixes with the lead free solder and lowers the melting temperature.Solder suckers can work very well.. a good trick is to get some silicone tubing and add it over the plastic nozzle and maybe cut the silicon tube at an angle. The silicon tube is flexible and heat resistant (or you can replace it often, unlike plastic which would burn/smoke/go bad and is hard) so you can hold the solder sucker over the solder you want to melt or you can have the silicone tube touching the iron tip and you may also create a better seal under the solder sucker.Every once in a while, you can just replace the silicon tube bit and you're back in business. You may want to oil the insides of a solder sucker like maybe once every 4-6 months. Also, buy good solder sucker, I have an aluminum one that's a bit longer than those cheap plastic ones.. has good suction.Careful with solder suckers on old boards and if your iron's temperature is too high... the suction can be strong enough to lift pads.I wasn't a fan of solder wick (braid) but found out it's because I had one with no flux and one with bad quality flux. Good flux on solder wick helps a lot but even if you find one, it helps to add extra flux on the board.Can be used on through hole parts... put the wick on sides of lead and press on the wick with the iron so that wick will absorb the solder while the lead moves away from the through hole wall ... repeat from multiple directions.Where the components may be heat sensitive, there's also those low melting point solder formulas with Bismuth and Indium and other metals which go liquid at something like 100-120 degrees Celsius.

author: HobGoblyn
author_rank: Unknown
timestamp: January 24, 2020, 11:20:14 pm
content: Quote from: mariush on January 24, 2020, 09:03:23 pmMany thanks, my flux is the the 100ml from tme that you’ve linked to, I got it a few weeks ago after you advised me in another thread (on building my lab). It’s the liquid one.What I can’t find is reasonably priced silicon tube.