28 Sep
2002
28 Sep
'02
2:35 p.m.
Perhaps this thread needs to be changed to "What not to do first...".
Tony Duell wrote::
<snip>
Please review the thread.
So far the original poster has been told to reform the caps with zero
testing, and now also to begin to unsolder
the damn chips from the PCB's. And Altairs do not use sockets.
Perhaps this is your restoration technique, but its not mine.
I guess you're relatively new here.
<snip>
Perhaps I've not been on the list for many years, but I've got a few
decades in the industry Tony.
<snip>
What's the problem with taking things apart????
Simply put, in your own words...
>Fine. However, the first rule of restoration of
_anything_ is not to make
>matters worse.
>
Pulling soldered-in IC's will cause far more long-term reliability
problems than you seem to be aware of.
This is especially true for older devices that were not as well treated
prior to packaging, and gas permiable
packages used on older TTL chips.
But as I'll get to later, this process WILL dammage even new chips.
Secondly, PCB etches are normally quite easy to repair. Solder a bit of
wire-wrap wire across the break. ICs are not easy to repair. Why are you
so concerned about the PCBs?
Because it greatly effects the original condition of the machine.
Look, I don't know who you are, I don't know what experience you've had
repairing classic computers. I do know what I've done. I do know what
I've seen happen when a PSU goes crazy. I also know I could desolder
every chip in an Altair without damaging either IC or PCB if I had to. As
for pulling ICs from sockets, well, I wouldn't even think about damaging
anything before doing that.
FYI...
I've done engineering work for companies like Lisp Machine Inc, Thinking
Machines Inc, Apollo Computer,
and NEC. I also had the great pleasure to work at the MIT AI lab, but
my formal training comes from the USAF
where I maintained combat air traffic control and electronic warfare
systems. I've got well over two decades in the industry, and I've been
restoring vintage computer hardware for over15 years.
So basically I've done engineering on computers with more CPU's than
your talking about having chips in your CPU.
I have been around the block more than a few times Tony.
<snip>
Then why was
the original poster reccomended to 'reform' the caps?
I don't recall ever suggesting this....
ROFL again. Based on your comments here I suspect I've worked on machines
where, based on the (lack of) available documentation, you wouldn't have a
clue how to start....
Is that so?
Maybe you should check to see if I was one of the ones who originally
designed them before you
make any more foolish assumptions.
Your getting a little bit more than arrogant here Tony.
Perhaps the reason it takes me so long before powering up a machine is
that I like to make sure I'm not going to damage anything. I don't like
making problems worse.
By unsoldering the chips?
If you think this does the least dammage, your grossly in error. As a
test engineer, I can direct you to any number
of volumes that will show you the dramatic increase in MTBF for
resoldered parts. This is known, for-sure dammage, not some risk of
dammage from a theoretical regulator failure.
Care to defend this position?