- How to replace bad CPU on circuit board? - 1 Update
| Jeff Liebermann <jeffl@cruzio.com>: Mar 06 10:57PM -0800 On Wed, 4 Mar 2020 17:31:34 -0800, Robbie Hatley >(These CPUs are not like the CPUs in PCs; they're 15mm-square >$5 8-bit 8MHz 100-pin CPUs with 25 pins on each side, surface-mount >soldered directly to circuit boards.) I can't tell what type of package that might be. My best guess(tm) is one of these: <https://en.wikipedia.org/wiki/Quad_Flat_Package#TQFP> A maker and part number for the CPU would be helpful. > Solder bath? (Might unsolder surrounding components.) > Cut pins? (Might damage traces.) > OTHER??? Hot air SMD desoldering station. Something like this: <https://www.google.com/search?tbm=isch&q=hot+air+smd+desoldering+station> You'll need a nozzle to match your chip: <http://new.ldbenterprises.com/smd-rework-station-nozzles/> You'll need to know the IC package type to order the proper nozzle. There are videos on YouTube on how to use these: <https://www.youtube.com/results?search_query=smd+qfp+desoldering> You'll also need flux and flux remover. A good binocular microscope, fan to blow away the smog, and an aluminum foil heat shield, are quite helpful. > external programming module which connects to a PC via USB; but I > don't know if such programmers can work in reverse, READING software > from a CPU instead of WRITING to it.) Most uP firmware is copy protected. That may not be possible. You'll need to get the instructions from the manufacturer of the product. If the device has a JTAG port, you might be able to do something with that. -- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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