Psion Organiser General Maintenance

This guide covers preventive maintenance for the Psion Organiser (Series 1, 1984). The priorities are the PP3 battery and its compartment, the Datapak slot contacts, the conductive rubber keymat and the LCD contrast circuit.

The Series 1 with its sliding cover off. The cover is held by a spring catch and comes away with a firm downward pull; the battery cover is behind, on the back of the machine.

Psion never published a service manual for the Series 1, and the 1984 warranty booklet states flatly that there are "no user-serviceable parts" inside. That warranty expired forty years ago; what it means today is only that you are working without a factory procedure, so go slowly and photograph everything.

⚠️ Safety

There are no mains voltages anywhere in this machine. It runs from a single 9 V PP3 and the highest rail on the board is a pulsed programming voltage of about 21 V generated internally for writing Datapaks — enough to be felt but not dangerous.

The real hazards are to the machine, not to you:

• Never fit a mains adaptor. Psion's manual is explicit: "You should not use a mains adaptor because it may damage your Organiser."
• Never remove or fit a Datapak with the machine switched on.
• Never SAVE after a LOW BATTERY warning — a half-completed EPROM write can spoil the remaining space on the pak.
• Observe anti-static precautions. Everything on the processor board is CMOS.

Batteries

The Organiser takes any 9 V PP3. Psion recommend alkaline or rechargeable types for longer life.

• Take the battery out if the machine is going into storage. A leaking PP3 in a sealed compartment is the single commonest way these machines are destroyed, and the electrolyte creeps along the connector leads into the case.
• The clock survives about fifteen seconds without a battery if the machine was switched off first, so a quick swap does not lose the time. Anything longer and the clock restarts from midnight on 31 December.
• Everything in RAM is volatile. Records live on the Datapak, not in the machine, so a flat battery costs you the clock rather than your data — but any unsaved current line is gone.
• Check the battery connector leads where they enter the compartment. These are thin and forty years old, and the moulded PP3 clip goes hard and cracks.
• Clean the PP3 stud contacts with a fibreglass pencil or a cotton bud and isopropyl alcohol if they are dull.

If a battery has already leaked, deal with the corrosion before doing anything else — see Battery Explosion, Capacitor or Corrosion Damage.

Opening the machine

1. Remove the battery.
2. Slide off the protective cover. Grip it just below the separation point and pull firmly downwards; it is retained by a spring catch and comes right off.
3. Remove both Datapaks (and the dummy pak).
4. The case is then held by screws in the back. Work slowly — the two internal boards are joined by a ribbon and a pair of pin headers, and the LCD is clamped to the edge of the processor board.

Photograph the board positions and the ribbon routing before separating anything.

The keyboard

The Series 1 keyboard is a conductive rubber keymat over gold-plated interdigitated PCB pads on the front of the processor board. This is the same principle Psion used on the Organiser II and on most calculators of the period, and it fails in the same ways.

• Keys that need a hard press are almost always dirt, not wear. Lift the keymat out, wash it in warm water with a little washing-up liquid, rinse in clean water and let it dry completely — no heat.
• Clean the PCB pads with isopropyl alcohol on a lint-free swab. Do not use an abrasive: the gold plating is thin and once it is through to the copper the contact will corrode.
• A key that does nothing at all while its neighbours work is a pad problem. A dead group of keys is a matrix problem — see the Psion Organiser Troubleshooting Guide.
• Reassemble with the keymat seated flat and no dust trapped underneath.

The display and contrast wheel

The LCD is a 16-character single-line module driven by an HD44780 controller, clamped against the processor board.

• Contrast is set by the thumbwheel on the right-hand side of the machine, which is a variable resistor (VR1) on the power board. Turning it clockwise darkens the display.
• If the contrast range has become poor or the wheel feels gritty, clean the track with a switch cleaner applied sparingly and work the wheel through its full travel.
• Missing dots, columns or a faint segment of the display usually mean the connection between the LCD module and the board has degraded rather than that the module has failed. Release the clamp, clean both mating faces with isopropyl alcohol and reseat squarely.
• Never lever on the glass. The LCD module is a metal-framed assembly and the glass will crack before the frame gives.

Datapak slots and paks

The pak slots are the busiest connectors on the machine and the ones most likely to give trouble.

• Clean the slot contacts with a foam swab and isopropyl alcohol. Contact cleaner may be used sparingly, but let it dry fully before fitting a pak.
• Keep a pak or a dummy pak in both slots at all times. Psion fitted the dummy specifically to protect the contacts, and an open slot collects dust and gets bent.
• Always switch off before changing a pak.
• Lay the machine face down on a flat surface while changing paks so you cannot press ON/CLEAR by accident — the keyboard is slightly recessed for exactly this reason.
• Store paks with the white light-shield label in place. It is there to keep ultraviolet light off the EPROM window; a pak left in sunlight without it will slowly lose data.
• Datapaks are rated to be formatted (UV-erased) up to 100 times, so a pak that has been round the cycle many times may simply be worn out.

Case and cover

• The sliding cover is retained by a spring catch. Check the catch and its spring — a weak one lets the cover fall off in a pocket.
• Clean the case with a damp cloth only. Psion's own instruction is not to use volatile fluids on the case, and it is good advice: the textured finish and the red keyboard legends do not survive solvents.
• Do not subject the machine to knocks or force, and keep it out of extremes of temperature and humidity.

Preventive maintenance checklist

1. Remove the PP3 if the machine is not in regular use, and inspect the compartment and connector leads for corrosion.
2. Clean both Datapak slots; confirm a real or dummy pak is fitted in each.
3. Check the contrast wheel moves smoothly through its full range.
4. Wash the keymat and clean the PCB pads if any key needs a hard press.
5. Confirm the clock survives a battery change (a good check that the power board's standby hold-up is still healthy — see the Psion Organiser Capacitor Replacement Guide).
6. Check the sliding cover catch and spring.
7. Verify SAVE and FIND on both slots with a known-good pak.

Recommended tools

• Small cross-head and jeweller's screwdrivers, plastic spudgers, an anti-static strap.
• Digital multimeter.
• Isopropyl alcohol, lint-free swabs, contact cleaner, a fibreglass pencil.
• Fresh 9 V PP3 batteries — ideally two, so a suspect one can be ruled out.
• A known-good Datapak for testing.
• Temperature-controlled soldering iron, solder wick and leaded solder if you intend to work on the power board.

See Recommended Tools for the general workshop kit.

Related pages

• Psion Organiser
• Psion Organiser Troubleshooting Guide
• Psion Organiser Capacitor Replacement Guide
• Psion Organiser II General Maintenance — the successor, whose power board is a development of this one
• Battery Explosion, Capacitor or Corrosion Damage · Recommended Tools