On 7/27/19 8:11 PM, Fred Whitaker wrote:
I have been having trouble with my REX chip becoming loose and losing
data as a result. The computer also locks up. I was wondering if
anyone had any ideas about better support for the chip corners,
instead of a loose piece of wood under it.
I was thinking of trying to find some small diameter thin stick on
feet, about 1/8 inch thick. Has anyone had a similar problem?
The problem will be the same with any of the ROM's on similar boards.
The Super ROM that I have is on a similar board but it also has a full
length spacer glued to the bottom of the board.
Until I can resolve this issue I am putting my REX chips in storage.
This is only true for the Model 100 and Model 102.
I have been fine-tuning a slightly modified version of REX and
3d-printed plastic carrier that might help with that. This design is
still in the works, not quite finalized yet, but good enough to use if
you wanted.
http://tandy.wiki/REX#REX_Hacking
Not the "build your own rex" link at the top, the stuff about "version
c8" at the bottom.
But that only helps you if you're up to building a new rex for yourself
from those plans, or getting someone else to. I'm not making or selling
those, just working on the design.
What you should be able to do with your existing unit is, before I made
the version using the 3d-printed carrier, I used layers of cereal box
paperboard, hot-glued or double-sided taped to the bottom along with a
ribbon, so the spacer is not loose.
The spacer you have might be slightly too thick for your socket (the
sockets aren't all exactly identical), and with the paperboard you can
fine-tune the thickness by adding or removing a layer. For one of my
machines, a single layer of paperboard plus the ribbon makes the perfect
thickness. For another of my machines, that's too thin and you need
another layer of paperboard (and double-sided tape).
Maybe you can play with that. Look for 1/2"permanent double-sided scotch
tape at Target or somewhere. Not foam, tape. Thin and not compressible.
Be careful about going too thin. If the pcb goes beyond the critical
depth and the socket pins snap out over top of the pcb, you will have
fun getting it back out without wrecking your socket pins. You'll have
to use a cut up credit card or junk loyalty card etc to push an entire
row of pins back at once.
Another thing I did for one unit was lay the ribbon down flat on a work
surface, dab a couple globs of hot-glue on the bottom of the rex near
the ends to either side of the flash chip, then lay the rex down on the
ribbon and hold until the glue hardens. the glue then forms a spacer of
the exact perfect height next to the flash chip, and, secures the
ribbon. The flatness of the table makes the glue flat and the right
exact height.
Then you just add a layer or two or three of cereal box to that. Three
is usually too much. It will be one or two. You have to hold the ribbon
flat too. One hand, thumb and forefinger to hold the ribbon flat to the
table and pull it tight slightly, the other hand to place the rex on top
and just press one finger down in the middle for a few seconds till the
glue cools a little.
--
bkw
