Hi Rob, I've seen lots of PLCC packages soldered directly to the board. Many BIOS chips were socketed, presumably because they were the last to get inserted unto a motherboard as BIOS firmware updates were issued during manufacturing.
Removal won't be easy but you could either: - Slip a Post-It note under the pins as you heat each one individually with a soldering iron to decouple it from the board. You can do this to two opposite sides first, then heat all pins at once on each remaining side while you slip the paper underneath to save time. - Carefully sever the top connection of each pin with a steel knife. Just don't let the pin get bent outward too much - it'll have lots of leverage to rip the pad off the board. - Use an SMD hot-air tool with a PLCC or TQFP nozzle. I'm always wary of overheating/delaminating old PCBs though. =] -- Anders Nelson +1 (517) 775-6129 www.erogear.com On Wed, Aug 16, 2017 at 2:10 PM, Rob Jarratt via cctalk < cctalk@classiccmp.org> wrote: > > I was out most of this evening, but I just had a quick look again and > think I have > > found something significant. Comparing the gate array pins on the two > boards I > > have, I see that on the board where the video is corrupted, there are two > pins > > that appear connected to 0V that are not connected to 0V on the spare > > motherboard. > > > > I have yet to attempt to trace the connections to these pins, I will do > that > > tomorrow as it is late here now, but I suspect it does not bode well for > the gate > > array :-( > > > > Regards > > > I have made an interesting, but sad, discovery. I traced both the two > apparently shorted pins on the gate array to two pins on the Chips & > Technologies 82C206 Integrated Peripherals Controller. Checking the 82C206, > I found lots of pins on that chip appear shorted to ground. I fear the > 82C206 has failed badly. > > I suppose that, happily, it looks possible to procure replacements for this > chip. I am slightly puzzled by the packaging of this chip though. It is > surface mounted on my CPU board, but the packages available for this chip > are PLCC which I assumed required a PLCC socket. Can PLCC chips be surface > mounted, or is it a subtly different packaging that I would need? > > There is no obvious damage from battery leakage near this chip, it was > close-ish to the damage area but the leak didn't reach it, so I think the > failure is either due to other damaged bits causing it to fail, or just > plain old age. Is there anything I could have missed that might make me > think it is faulty when it isn't? > > Regards > > Rob > >
