Re: Replacing SMD component

Ashhar Farhan

Here is what I do. I am quite butterfingers at this, btw.
I use whatever soldering iron I have, and then (hear this, the transistor is dead anyway), i load up liberal bits of solder on all the pads. solder helps in retaining the heat for the next step. next, i start to heat the pads, one by one, waiting until one is melted then move to the other. at the same time use a toothpick to gently keep pushing the transistor away. at some point, all the three will be simulatenously melted enough for the transistor to fly away. Many a times, it comes stuck to the iron itself (i use the iron to push it away - bad boy, i am). 
- f 

On Tue, Sep 8, 2020 at 10:29 PM JE Jesson <jejesson4@...> wrote:
In a pinch, a toothpick with a bit of clay helps position the surface mounted part into position and soldering one leg to anchor the part.  Solder the other leg and make sure both sides are glossy. 


On Tue, Sep 8, 2020 at 10:27 AM R. Tyson via <> wrote:

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

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