Psion Series 3 General Maintenance

A Series 3. The case, hinges, button bar and battery arrangement are shared with the 3a, 3c and 3mx, so most maintenance is common to all four.

Preventive maintenance for the Psion Series 3 (1991).

The Series 3 shares its case, hinges, button bar, keyboard construction and battery arrangement with the 3a, 3c and 3mx. The full common procedure is in the Psion Series 3a General Maintenance guide — this page covers what is specific to the original Series 3.

⚠️ Safety

No mains voltages. Two AA cells, and a +16 V Vh rail that appears at the SSD slots only when writing or formatting a Flash pack. Everything is CMOS; use an anti-static strap.

What is specific to the Series 3

Timekeeping: take the clock seriously

This is the one maintenance difference that really matters.

The Series 3 has no hardware real-time clock. It keeps time by waking the CPU periodically — roughly every eight hours — to update the count. If the CPU cannot start because the main batteries are absent, the time is simply lost.

So on a Series 3, unlike a 3a:

• Do not store the machine with the AA cells out and expect the clock to survive.
• Change the AA cells promptly rather than leaving the machine running on backup.
• Expect to reset the clock after any extended storage, and check it after every battery change.

Backup cell

The Series 3 takes a CR1620 lithium coin cell, as do the 3a and 3c. Replace it on a schedule rather than on failure — it is what holds your data during an AA change.

Display

The Series 3 screen is 240 × 80, black and white only — no grey plane and no backlight. It is a physically different panel from the 3a's and uses a different ribbon, so a 3a lid will not simply transplant onto a Series 3. Bear that in mind before buying a donor.

Sound

A piezoelectric buzzer driven directly from ASIC2, at high or low volume, and either by toggling a register bit or from the ASIC1 timer overflow. There is no microphone and no sound recording — those arrived with the 3a. A Series 3 that will not record audio is not faulty.

Serial

9600 baud through the optional link pod, with the comms software held in the pod's own ROM rather than in the machine. A Series 3 that has "lost" its comms software has usually just lost its pod.

Everything else

For the shared items — the battery lead, opening and closing the lid, the button bar, the SSD slots, the keyboard membrane, case cleaning and why the Series 3 family is not a recap candidate — see Psion Series 3a General Maintenance.

The single highest-value habit on any Series 3: open the lid squarely with two hands and stop at a comfortable angle. Over-opening is what shears the visible hinges.

Preventive maintenance checklist

1. Back up to an SSD or a PC.
2. Note the time before, and reset it after, any battery work — this machine will lose it.
3. Remove the AA cells for storage; check the compartment for corrosion.
4. Replace the CR1620 if you do not know its age.
5. Inspect the battery lead where it flexes, and re-seat the two-pin connector.
6. Check all four hinges for cracks.
7. Confirm the button bar sits flush and responds.
8. Clean both SSD slots and confirm packs are recognised.

Related pages

• Psion Series 3 · Psion Series 3 Troubleshooting Guide · Psion Series 3 Hinge Repair
• Psion Series 3a General Maintenance — the shared procedure
• Battery Explosion, Capacitor or Corrosion Damage · Recommended Tools