Trying to solder capacitors in an IBM M2

digital_matthew · 10 Apr 2018, 20:20

Hey everyone, I'm trying to solder new capacitors into an IBM Model M2. I removed the old ones with heat and pliers, and that was easy enough, but when I try to apply new solder it doesn't want to stick. I'm using electronics grade lead based solder with a lead rosin core, so I didn't think that flux would be necessary. Do I need it, or am I doing something else wrong? Thanks!

Blaise170 · 10 Apr 2018, 20:30

You shouldn't need any additional flux since it is rosin core. What size iron are you using?

j0d1 · 10 Apr 2018, 20:34

Things you can try:

1. Add solder on the leads of your capacitors before trying to solder them to the pads.
2. Add solder on the pads before trying to solder the capacitors on them.

In both cases, apply a little bit of solder paste on the capacitor leads and the PCB pads before applying the solder.

Also, if you can solder at a higher temperature, try that.

digital_matthew · 10 Apr 2018, 20:49

Thanks, guys. I've attached a photo of the cheesy soldering iron I got from Amazon as well as the replacement tips. I should also try using a higher temperature.

Blaise170 · 10 Apr 2018, 20:50

In general I recommend a chisel tip for keyboard related soldering. It's the perfect combination of heat transfer and size in my opinion.

Sangdrax · 11 Apr 2018, 00:56

Sounds like the pads aren't getting hot enough to me. The other guys are right. Swap out to a tip with a flat surface for heat transfer and make sure you can get a little solder to stick on the pads before you try to attach the capacitors.

andrewjoy · 11 Apr 2018, 11:30

Blaise170 wrote: ↑You shouldn't need any additional flux since it is rosin core. What size iron are you using?

You can never have too much flux! If your doing SMD its almost a requirement , somtimes you have to add the solder to the iorn ( you should never normaly do this) and just touch the pad with it, or if your doing a big chip you would do the same with a well tip so flux is needed.

I would use the chisel tip.

Make sure both pads are clean and free of solder
Put some ( not loads ) of solder on one pad
flux it up
hold the cap in place with tweesers
touch the pad with the soldering iorn to melt the solder and let the cap press into it.
with the flux on the unsolderd pad add some solder to your iorn and just touch the pad for a second or two , the solder will flow onto the pad