HrastProgrammer
12-10-2014, 09:53 AM
Prenosim u originalu s drugih foruma, možda će nekome biti korisno ...
***
Some time ago I bought a cheap spare A6 ASIC board with faulty filter 2 on voice 14. As I already bought some spare chips it was my intention to find a technician who could eventually replace the faulty chip.
But, in the meantime I bought a proper soldering/desoldering stations and I decided to do it by myself.
There are two important steps here: desoldering the old chip and soldering the new one. I planned to use hot air station for desoldering but even after practicing the procedure on lots of old PC motherboards and cards, I still wasn't confident enough to repeat it with the ASIC board. The problem is - there are a lot of small SMD components around the chip and I was afraid I could blew some of them away using hot air. OK, the solution was to fix them using a kapton tape but still - I didn't have enough confidence to do this.
As I didn't have to save the old chip, I decided to use a sharp jewelry pliers (like those (http://www.ebay.de/itm/Jewelry-Electrical-Wire-Cable-Cutters-Cutting-Side-Snips-Flush-Pliers-Hand-Tools-/161382278640?pt=DE_Baby_Kind_Baby_T%C3%BCr_Treppen schutz&hash=item25932225f0)) to cut all pins one by one and desolder them using a regular soldering iron. This is rather slow process and patience is the key (cut a pin - desolder a pin) but I wasn't in a hurry. Another good side of this approach is that you don't really apply any excessive thermal stress on the board.
After cutting/desoldering all pins and removing the chip I carefully removed (using a solder wick) the remaining solder from the pins on the board. Again, patience is the key because you don't want to damage or lift off the pins. You really have to remove all remaining solder - to have a nice clean surface which makes aligning of the new chip much easier.
Now goes the soldering. The correct chip orientation and precise alignment is the key here. After you align the chip just solder one corner (one pin), then correct the alignment a little if necessary and solder the opposite corner. The rest is, more or less, straightforward. I don't spare flux because it makes all steps much easier and you can simply clean the excessive flux after you are done with soldering. And I usually use higher temperature which (in combination with proper amount of flux) makes soldering easier as well - just one short touch per pin. Don't worry if you accidently bridge two pins together - just use solder wick to remove excessive solder.
That's it ...
A skilled professional can do all this much faster using hot air but I am perfectly satisfied with the result produced by the above method - the board tuned perfectly and continued to do so for the last few weeks :)
Disclaimer #1: If you try to do this by yourself then I am not responsible if you damage the board/chip, burn your fingers or house, kill yourself or your dog, etc.
Disclaimer #2: I have enough A6 spare boards and chips to keep me and my two Andromedas (Andromedae?) safe for years to come. But I don't sell those chips and boards, no way.
***
Some time ago I bought a cheap spare A6 ASIC board with faulty filter 2 on voice 14. As I already bought some spare chips it was my intention to find a technician who could eventually replace the faulty chip.
But, in the meantime I bought a proper soldering/desoldering stations and I decided to do it by myself.
There are two important steps here: desoldering the old chip and soldering the new one. I planned to use hot air station for desoldering but even after practicing the procedure on lots of old PC motherboards and cards, I still wasn't confident enough to repeat it with the ASIC board. The problem is - there are a lot of small SMD components around the chip and I was afraid I could blew some of them away using hot air. OK, the solution was to fix them using a kapton tape but still - I didn't have enough confidence to do this.
As I didn't have to save the old chip, I decided to use a sharp jewelry pliers (like those (http://www.ebay.de/itm/Jewelry-Electrical-Wire-Cable-Cutters-Cutting-Side-Snips-Flush-Pliers-Hand-Tools-/161382278640?pt=DE_Baby_Kind_Baby_T%C3%BCr_Treppen schutz&hash=item25932225f0)) to cut all pins one by one and desolder them using a regular soldering iron. This is rather slow process and patience is the key (cut a pin - desolder a pin) but I wasn't in a hurry. Another good side of this approach is that you don't really apply any excessive thermal stress on the board.
After cutting/desoldering all pins and removing the chip I carefully removed (using a solder wick) the remaining solder from the pins on the board. Again, patience is the key because you don't want to damage or lift off the pins. You really have to remove all remaining solder - to have a nice clean surface which makes aligning of the new chip much easier.
Now goes the soldering. The correct chip orientation and precise alignment is the key here. After you align the chip just solder one corner (one pin), then correct the alignment a little if necessary and solder the opposite corner. The rest is, more or less, straightforward. I don't spare flux because it makes all steps much easier and you can simply clean the excessive flux after you are done with soldering. And I usually use higher temperature which (in combination with proper amount of flux) makes soldering easier as well - just one short touch per pin. Don't worry if you accidently bridge two pins together - just use solder wick to remove excessive solder.
That's it ...
A skilled professional can do all this much faster using hot air but I am perfectly satisfied with the result produced by the above method - the board tuned perfectly and continued to do so for the last few weeks :)
Disclaimer #1: If you try to do this by yourself then I am not responsible if you damage the board/chip, burn your fingers or house, kill yourself or your dog, etc.
Disclaimer #2: I have enough A6 spare boards and chips to keep me and my two Andromedas (Andromedae?) safe for years to come. But I don't sell those chips and boards, no way.