16 May
2010
16 May
'10
11:39 a.m.
On Wednesday (05/12/2010 at 06:47PM +0100), Tony Duell wrote:
yes... and to make matters worse, some of the devices were soldered
in without sockets too! I first suspected the 8279 display+keypad
Pity...
That's on the ToDo list. Unfortunately the
ROM extension location at A15
has no socket installed and all the holes are flowed over with solder. So
The PCB was probably wave-soldered with no socket in place. Seems
strange, on an experimental machine like this not to fit the expansion
socckets, but anyway... controller and so I had to sacrifice it by cutting the
pins off the
package and then desoldering each pin one at a time. Sadly, that did
not fix the problem and I wasted a nice ceramic packaged 8279 circa 1976.
Normally I find I can desolder the device and sae both the chip and the
PCB. I think I've mentioned before that the trick is, after sucking off
the solder, to use a small flat-blade screwdriver on the component side
to puse each pin towards the IC body and break the remaing solder bond.
A couple of times I have had to cut off the pins. I've found that with a
good pair of close-cutting end nippers you can leave enough of a stub on
the package to then be able to solder the device to the top of a normal
DIL socket which yo ucan then plug into another DIL socket to use it. I
wouldn't trust it in somebody else's machine unless I _had_ to, but I've
savaged a dew hard-to-get ICs that way.
The best way I've found to do this is to hold or clamp the board
vertically, melt th solder with an iron on one side and suck with a
solder sucker from the other. It's not too bad doing it for a 40 pin
socket, it gets boring fast when you have to clear out 16 or 32 16 pin
locations for a memory upgrade (been there, done that, don't wear
t-shirts ;-))
yes... or shorts. Do you call them shorts over there?
aka, short pants.
Yes 'shorts' has the same meaning over here. But 'pants' tends to refer
to underwear.
I still have the scars on my leg from dropping solder
blobs onto them
while wearing shorts at the bench as a kid. Not cool.
Ouch. I can still just see the burn on the back of my hand where I
dropped solder on it <mumble> years ago...
-tony