Heheh, that's a cool idea. I use a post-it note, sliding a non-sticky side under the pins (from the rear of said pins) as I drag the iron across all the pins.
=] On Sun, Jun 25, 2017 at 11:27 AM Pete Turnbull via cctalk < cctalk@classiccmp.org> wrote: > On 25/06/2017 11:46, Rob Jarratt via cctalk wrote: > > > I have done a bit more tracing of components and have come across a > > possibly anomaly. The signal that won't go low enough goes to the > > input (pin 2) of a 74LS125 buffer. > > As soon as I saw "74LS125" I thought, "Oh, yes, another one". That's a > fairly early design tri-state buffer, and in my experience they're not > very robust. We used to replace lots of those, though admittedly I'm > referring to the DIL version. Worth checking it out. > > If you can't desolder all the SMD pins, try this trick: for each side, > thread a piece of enamelled copper wire under the chip near the pins. > Tie or wrap one one to some nearby component and hold the other end in > your hand. Starting at the end with the wire you're holding, heat each > pin with your soldering iron, and drag the wire under it, thereby > breaking its contact with the board. > > Failing that, apply a tiny amount of flux to the pins, and heat it up > with a hot air gun, preferably a temperature-controlled one, and lift it > off with forceps (or flip it over with a small screwdriver). > > -- > Pete > Pete Turnbull > -- -- Anders Nelson +1 (517) 775-6129 www.erogear.com
