I need to replace at least 2 of my ACT244 chips on the Rev L TIU. I am competent at soldering, however, I am curious if there are any tutorials or videos or other help available showing best procedure for replacement???
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Honestly I don't know or have not decided the best procedure. I have multiple tools- hot air rework, temp controlled soldering iron, and so forth. The fundamental problem is the nearby surface mount components. If you use hot air, you need a mask- either Kapton tape or some other form of blocker to prevent the hot air from desoldering components nearby.
As such, I used the drag solder method I add solder to the existing chip legs to bridge them and help conduct the heat to all of them at the same time. The thermal mass gives you time to keep heating both sides or rows of pins. Then use tweezers to move the chip once everything is liquid. This is most definitely a skill, not intuitive- you are adding massive amount of solder to remove something, and as such- again that Kapton tape solder mask can prevent a disaster.
I live to watch Dave's videos from time to time https://www.youtube.com/watch?v=588iV07nEdM
Also Louis Rossmann has excellent hot air rework skills https://www.youtube.com/watch?v=gl9NuCiDR7s
I also splurged and got myself recently a microscope with LCD "10'’ LCD Digital Microscope - 1300X Soldering Microscope with 32 GB Card - Opqpq USB Coin Microscope with Metal Stand, Ultra-Precise Focusing 12MP Camera, 10 LED Fill Lights, Remote, UV Filter"
And my soldering station is an 852D++ but there are so many newer equivalents these days.
But the other near daily used tool is the Hakko FR301 desolderng tool. I use it to clear the pads and fix bridged pins after drag soldering the new chip in.
Also, I only use Kester 24-6337-0010 44 Rosin Core Solder 63/37 .020 1 lb. Spool solder and no additional flux.
You also want good tweezers
Also, to make life easier, you can use chipquick which is a low melting point alloy solder.
I've used it once or twice when I first was getting into surface mount, but being honest, it can get costly all the time. But for a sngle 2 chip repair job, yes it could make it easier and less stress being a lower temp and stay melted way longer.
Example video https://www.youtube.com/watch?v=gaoSU8Cb9yY
Much appreciated. Thank you for taking the time to explain and link relevant videos. I will watch and learn. I'm a little weary of hot air given the tight quarters nearby these chips. I have not done a lot of surface mount soldering.
For the 74ACT244 chips, I just use the soldering iron, the lead spacing is sufficient to allow that method. I have the 852D+ rework station, but I only use the hot air tool, the soldering is done with my Hakko FX-888D soldering station.
