27 Oct
2007
27 Oct
'07
3:36 p.m.
On Sat, 2007-10-27 at 00:25 +0100, Tony Duell wrote:
Before you do this, make extensive notes of what goes where. I didn't,
Ooops, yes...
In particular record what the cables conneect to what, and which way up
connectors go.
Make a diagram of where the PCBs go. It may be worth putting numbers on
all the PCBs, indicating which slot they came out of if there are several
identical PCBs that have to e put back in the same slots (an example of
this is the monostable PCBs in an RK11C. They're all the same
electrically, but are set to different time delays. Unless you want to
have to set the whole thing up from scratch, get them back in the same
slots!).
In some cases I make a note of the order of nuts, washers, solder tags,
etc on things like earthing screws.
Needless to say a notebook and pen is always to hand when I take a
machine apart. It may be old-fshioned, but I've yet to find a computer
that's anywhere near as convenient!
I've never found taking photos to be much help. It takes considerable
time and trouble to get a picture which actually shows the machine in
sufficient detail to be useful in putting it together again.
Another thing I do is get a couple of those partitioned boxes sold for
storing screwsm etc. When I take a machine apart, I put related bits of
fixing hardware i nthe compartments. Maybe the first compartment has the
tope cover screws, the nect one has the PCB hold-down clamp screws, and
so on. Taht way washers, nuts, etc are kept with the appropraite screws,
saving a lot of confusion later.
What is
the general process in checking an old system?
My procedure (for which I've been flamed here, I might add) is as follows
:
1) Dismantle the machine as far as is sensible. Do a visual inspection
for when I first got my PDP11, and was fortunate in that
a) it's a fairly
simple machine with not a lot to get wrong, and b) I had enough sense
and tools to figure out how it was meant to be...
The worst thing I ever did was dismantle the keyboard of an HP9815
withoug doing a keycap diagram. I'd not realised the keys would fall out
when I took the PCB off. I then had to send a panicky e-mail message to
several known-owners of said machine asking for the layout.
-tony