
Upgrading by yourself
the RAM of your HP48G to 256K
This document is based on the file 48GS256K.ZIP. The original
document describe how to upgrade your HP48G(S) to 256K with standard DIL
ram packages. I would like to thanks Thomas Otten and Thijs Kaper
for their initial works.
In this document, I explain how to use SMD (surface mounted chip)
ram chips to do the same upgrade, but for HP48G only. If you want to upgrade
the HP48S, you should refer to the original file. Moreover, you'll find
some pictures showing how to open your HP without damages,
and what looks like the upgrade.
WARNING:
Do the upgrade only if you know you're qualified to do it !
Watch out for any Static-discharges !
Of course this upgrade is at your own risk, you lose all waranty, if you
had any left......
Parts needed:
- 2x 128K (8bit) static ram chip SMD package (SO32)
part #: HM628128LFP-8 (Hitachi) or KM681000BLG-7L or anything equivalent
- 1x 74HC00 SMD
- 1x 1 Mohm resistor
- tiny wires
You need also a thin soldering iron. The soldering tip
should be less than 2mm (1/10 inch) wide.
You'll need as secondary accessories:
- a hair dryer
- a drill (diameter: 4 mm)
- matches and very thin screwdrivers
- a needle
- adhesive tape
Provide yourself also with a lot of patience!
Let's start!
The numbers inside brackets are the size of the document with pictures.
- Open your HP.
This part was originally written by Paul Smith. All pictures are my work,
as the html translation.
- Are you sure? Ok, backup your memory!
- Remove carefully the overlay (31k)
- Remove 10 plastic rivets(43k)
- Pull apart the two parts of the case(29k)
- Look inside (119k)
- Upgrade
- 32k to 128k (easy) (46k)
- 128k to 256k (more difficult) (10k)
- Close & Test (6k
& 31k)
Useful datas:
Credits:
- All the people mentioned in the file 48GS256K.ZIP, especially Thomas
Otten, Thijs Kapper, Paul Smith,...
- Eric Pfister (HB9VAT), who tried first the upgrade with SMD ram and
give me some!
- Jean-Marc Borer, who helped me to take the pictures
- Can Kekevi, who scanned the pictures
