foft wrote: Sat Apr 08, 2023 10:07 am So I just ordered some copper tape to try to fix these in a few weeks. A little bit of scraping of the adjacent vias and a bit of high temp Chemtronics CR2500 epoxy and it'll be golden. Or at the very least frustrating enough to drive me
)I desoldered such things using Wood's alloy (melting point 70C), you need to dilute the tin on the soldering pads with this alloy and then lightly heat it with hotair ...foft wrote: Fri Apr 07, 2023 9:39 pm Arg, built another one and it would have worked except... I got a little blob of solder under the surface mount socket. These are really tricky to remove, I think because they hold a lot of heat and ... melt!
So I tried to remove it with hot air, then gave up. Then decided to cut it off and desolder bit by bit. Now 14 pads are gone.Oh well, live an learn. I think my mistake was to use paste for the SMD header, I'll hand solder it on the next try, like on the first one.
Oh well, off for Easter hols and forget about it then I'll try again! Its all good practice and there are still enough PCBs for the 3 in line.
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Thanks this sounds super-useful. Which one do you buy? I see Wood's itself has toxic vapours, are the various similar low temp alloys the same - i.e. need extra ventilation vs simple soldering?markus0321 wrote: Tue Apr 11, 2023 10:28 am I desoldered such things using Wood's alloy (melting point 70C), you need to dilute the tin on the soldering pads with this alloy and then lightly heat it with hotair ...
Of course. If I sell the repaired one I'll be very clear with whoever is getting it... More likely I'll sell mine and keep this one for me.
Many thanks !foft wrote: Wed Apr 19, 2023 9:48 pm Of course. If I sell the repaired one I'll be very clear with whoever is getting it... More likely I'll sell mine and keep this one for me.
I'm back from Easter holidays and just started to build the remaining three ones. So far the PLX chips are on all three and looking good. I did these (+CPLDs) after the birdseed the first time and it made some pins hard to access.
I'm going to take my time with these so it'll be a few weeks before I finish and test them I think.
So it's better to have good ventilation. I still used low-temperature tin, but it is twice as high a temperature needed to desolder the elements. I use Wood's alloy only in such "difficult" cases and not very often. I recently bought it from our Allegro auction site, but I also see it on ebay.foft wrote: Wed Apr 19, 2023 9:48 pmThanks this sounds super-useful. Which one do you buy? I see Wood's itself has toxic vapours, are the various similar low temp alloys the same - i.e. need extra ventilation vs simple soldering?markus0321 wrote: Tue Apr 11, 2023 10:28 am I desoldered such things using Wood's alloy (melting point 70C), you need to dilute the tin on the soldering pads with this alloy and then lightly heat it with hotair ...
markus0321 wrote: Fri Apr 21, 2023 1:13 pm So it's better to have good ventilation. I still used low-temperature tin, but it is twice as high a temperature needed to desolder the elements. I use Wood's alloy only in such "difficult" cases and not very often. I recently bought it from our Allegro auction site, but I also see it on ebay.
foft wrote: Sun Apr 30, 2023 9:42 pm My gluing of the damaged one didn't go so well. I cut copper pads and stuck them on. Many seem solidly glued and others ... move around rather too much! I probably need to re-glue the problematic ones, before trying to wire up the new pads to the broken traces.