S3a 512kB upgrade

Updating your old Psion S3a with only 256kB of memory to 512kB is fairly easy! All one has to do is to solder in the two missing SRAM chips. The chips are easy to get from any electronic parts dealer.
The possible types are:

Static RAM, 128k*8, 100ns (or less), LP SOP32
Sony CXK581000M-12LB (those were in my S3a originally)
M628128LFP10
628128
438128
20100

Those chips are all SMD (surface mounted device). If you want to upgrade you have to have good soldering experience or know one who has. The chips have half pitch, i.e. pins are (middle to middle) 1.25mm away from each other. That is some kind of tight but managable. Here in Germany Simons Elektronik was a good source for them. I paid 61,40DM inclusive postage and packing. Compared to 199,00DM Psion wants for the upgrade I think it is fair :)

Opening the Psion

First of all backup your data! You will definitely loose all data on your Psion during the follwing process and will be lost without a backup! You should also try to wear a grounded antistatic wristwrap during the whole procedure in order to protect your Psion from an electro static shock.
Let's go! Close the S3a and open the SSD B drive bay and remove the backup battery. Then remove the main batteries and leave the battery cover off. Then open both drive bays and remove the two screws in there. One may be hidden under the void warrenty label :) You will loose your warrenty now ... Now open the S3a again. Now it becomes tricky. You will have to remove the keyboard holding cover now. The cover is snapped into the main case and you have to bend the main case a bit in order to snap it out. The two 'snaps' are at the front of the cover beneath the space key. pull the main case back a bit and try to pull the keyboard cover out. Be careful here in order not to break it! Now carefully remove the whole cover. This is tricky too, because the back left and right edges refuse to come out easily. After that you should see the naked keyboard rubber with the keys on top. Unless you want to reassemble the keyboard (I do not recommend this) try to pull down the whole thing onto something flat like a piece of thicker paper or so. And here you are with the mainboard! Now remove the four screws in the battery compartment and remove the battery holder. Attention! The batteries are connected through two thin cables and a plug with the mainboard! Remove the plug carefully and pull out the cable.

Removing the mainboard

This is mostly easy.
The mainboard is connected to a smaller board underneath it with removable connectors. The smaller board contains the speaker and both connectors for the SSDs. Take a small screwdriver and carefully pull the mainboard out. Start in the middle of the case (same position as for the keyboard cover). Do not bend the mainboard too hard! At some point it should just snap out a bit. The difficult part now is to remove the mainboard from the case. The connector for the serial interface at the upper left edge still holds the board. Get the screwdriver again and push it in a bit; hold it there. Now carefully remove the board. There are no wires connected to it so you should have the plain board in hands now.

Ever had a look at it?

Turn the mainboard over and have a closer look at your Psion! You should now see a fat quad-pack chip on the right (that's the main Psion ASIC with most of your Psion in it :) some other part in the middle and some chips on the left. The leftmost chip(s) is the ROM chip. The german version does not have the builtin spell checker so there are two free ROM pads. The chips to right are the SRAM chips and here we are! You should see two identical SRAMs with two free pads to the right. Those are the free pads where your new memory will be located.

Get your soldering iron!

Now the most difficult part. Have a closer look at the soldering pads for the two new chips. Are they pre soldered as mine were? Then you have an easy job now! If not you are at your own now, becasue mine were, sorry! Now take one of the new chips and lay it on the board, on the pads. Be careful with positioning the chips. They have to be in the same orientation like the two already in there! Lay them exactly centered on the soldering pads. All pins have to have close contact. Now get your soldering iron and first solder the upper left and lower right pin to fix the chip on the board. Soldering should be easy because you only have to heat the pins and press them on the pre soldered pad. Do not press too hard or too long! Just as long as it it needs to give good contact. Too long could burn your mainboard or destroy the keyboard on the other side! Do this with all the pins and the second chip.

Look again!

After soldering have a very close look at what you did. Are all contacts made? All pins connected? None forgotten? No short circuit between two pins? Fine!

Reassembly

Just reverse order the above steps and you should be fine within five minutes maximum. If everything is connected insert the main battery first and check functionality.

Does it work?

Open the Psion and press ESC. You should hear an immediate beep and then nothing should happen for some time (approx. 20 seconds). After that the Psion S3a logo should appear! Now check the free memory on the system screen using the menu. You should have approx. 400kB free (or more) now!

OK. You have just upgraded your Psion! Congratulations!
But beware that I cannot guarantee anything for the above process! If you crash your Psion I cannot be held responsible for anything. And you will void your warrenty, remember!

Perhaps you want to have a look at another page on this topic from a friend of mine http://www.si.unix-ag.org/~fionn/e/Psion/Inside.html