Replacing SMD component

R. Tyson


Due to a senior moment ( I am old enough to be entitled to have them) I need to replace Q90 which is a dreaded SMD device. Ten SMD 2N3904 transistors arrived with the mail today. Wow, they are so small. I had previously found the location of Q90 on the board and verified it was no longer functioning and noted it's position, which is not too bad to get at. I am now waiting for a 1mm tip for my soldering iron and more importantly some liquid flux.

Meanwhile I had a look at YouTube and found some ideas for replacing SMD components without special tools. I opted for the following idea, photos below.

I cut down an old, knackered soldering bit and cleaned it up as shown in the photo. I then applied some heat conducting paste (probably not essential but I already had some). I then wound 1mm copper wire onto the remains of the soldering iron tip. The two prongs that are formed should enable me to heat all 3 connections on the transistor at the same time and it (should) come off the board easily. Well.... it looks easy when the guys do it on YouTube !

Reg                   G4NFR

Join to automatically receive all group messages.