Psion Series 5 General Maintenance

A Series 5. Mechanically it is the same platform as the 5mx, so the maintenance is shared — but the screen ribbon, the mainboard and the RAM are not interchangeable between them.

Preventive maintenance for the Psion Series 5 (1997).

The Series 5 and the 5mx share the same mechanical platform, so the full common procedure is in Psion Series 5mx General Maintenance and applies here. This page covers what is specific to the Series 5, and quotes Psion's own service manual where it has something to say.

This is the one Psion for which the factory service manual survives — see Psion Series 5 Service Manual.

⚠️ Safety and data

Straight from Psion:

• Do not remove both the lithium dry cell and the main batteries without first backing up, or without external power attached. Removal of both battery sources will erase all information stored in internal memory.
• Use the stylus, not a metal tool, to release the lithium cell — insert it beneath the cell next to the voltage details in the base moulding. A metallic tool may short the cell.
• Danger of explosion if the lithium battery is incorrectly replaced. Replace only with the same or an equivalent type.
• Do not bend the LCD module — the circuit board is prone to fracturing. If it breaks, keep the liquid crystal out of your mouth and eyes and wash it off skin immediately with soap and plenty of water.
• Full anti-static discipline: minimise handling, transport in antistatic bags, wear a grounded wrist strap, pick components up by their bodies and never slide them across a surface.

Batteries

Two AA cells and a lithium backup cell, giving around 35 hours.

Two notes from the manual that save a lot of misdiagnosis:

• Some brands of battery are shorter in length than the European average and can give poor contact, resulting in incorrect low battery warnings. Try a different brand before suspecting the machine.
• Rechargeable batteries have a very low usage time in this machine and can give the false impression that the Series 5 is draining them too quickly.

Replace the lithium backup cell on a schedule. It is the only thing holding the RAM disk during an AA change.

The user reset switch

On a Series 5 the user reset switch forms part of the lithium backup battery's negative contact, reachable by opening the backup battery cover and pressing it with a pointed instrument.

That has a maintenance consequence worth knowing: a lithium contact that has been bent down towards the PCB can hold the machine in permanent reset. Psion list exactly that as a fault cause, with the remedy being to bend the contact away from the board. Check the contact geometry whenever the backup cell is out.

Doors and mouldings

• The battery cover has silicone-based lubricant applied to its running surface at both ends during manufacture, to help the rotating movement it performs in use. A replacement door should have the same lubricant applied.
• The hinge cover moulding contains the battery door, the RS-232 door and the IrDA window; each can be snapped out and replaced individually.
• Remove the hinge cover with the battery housing door closed — it will not come off otherwise.
• Do not over-tighten the three case screws. They purchase into the chassis moulding and strip easily.
• Psion's instruction on cosmetics: case mouldings are finished as assemblies, so small colour variations exist between batches. Always replace the entire case set if one moulding is damaged.

Dictaphone

The Series 5 has Play, Record and Stop buttons and a status LED. Psion's own test criterion is a good maintenance check: the buttons should press in and release easily of their own accord. A switch that is sticky or needs help to release should not be manipulated — it is a fault, not something to work loose.

The pen eject mechanism

Check the pen eject mechanism has not become dislodged before replacing the base. Its spring drops out if you are careless, and it is easy not to notice until the machine is back together.

Reassembly discipline

Psion's own cautions, all of which are easy to get wrong:

• Insert the flat flexible cables squarely. Inserting an FFC into a connector at an angle can cause short or open circuits. Retain the existing bends in each cable so the components line up correctly on the main PCB.
• Replace any label you removed with a new one. Do not re-fit a label that has already been peeled off.
• Extreme caution when replacing the LCD in the outer moulding — if the screen is not wholly centred it is very easy to damage the LCD or the digitiser.
• Keep dust and fingerprints out from between the digitiser and the LCD when reassembling them.
• Hold the LCD assembly correctly: the drivers along the bottom edge of the panel are very fragile and break easily.
• Have the machine open when refitting the main PCB and the base, so the on/off and door-warning switches are not fouled, and leave the Memory Disk and lithium doors open.
• Check the backlight whenever the LCD assembly is broken down — it is of delicate construction and is prone to damage during servicing.

Screen ribbon and hinge

The Series 5 suffers the same two mechanical failures as the 5mx — a cracking screen ribbon and brittle hinge-wire hooks — and the same preventive discipline applies: open the lid squarely, avoid repeatedly opening and closing it, and back up regularly because the ribbon fails without warning.

The Series 5 screen ribbon is a different part from the 5mx's. See Psion Series 5 Hinge Cable Repair.

Capacitors

Not a recap candidate. The Series 5 is a low-voltage surface-mount design running from two AA cells, and Psion themselves recommend that repairs are carried out at circuit board level rather than at component level because of the high-density surface-mount construction.

Note also what Psion blamed for excessive standby current in their own factory test: the DRAM, dry joints and floating inputs, and shorts caused by metallisation of the plastics onto the PCB. Capacitors are not on that list.

For the small number of situations where capacitor work is justified — corrosion damage, a shorted tantalum, unexplained standby current — see Psion Series 5mx Capacitor Replacement Guide, which covers the same board technology.

Preventive maintenance checklist

1. Back up before touching the batteries.
2. Replace the lithium backup cell if you do not know its age, and check the contact is not bent towards the PCB.
3. Try a different AA brand before believing a low-battery warning.
4. Check the battery door still rotates smoothly; re-lubricate with silicone grease if not.
5. Confirm all three dictaphone buttons release of their own accord.
6. Check the case-open and CompactFlash door switches operate.
7. Clean the touchscreen, the IrDA window and the serial connector.
8. Inspect the screen ribbon and the hinge hooks under magnification whenever the machine is open.

Related pages

• Psion Series 5 · Psion Series 5 Troubleshooting Guide · Psion Series 5 Hinge Cable Repair
• Psion Series 5 Service Manual — the factory manual
• Psion Series 5mx General Maintenance — the shared platform procedure
• Battery Explosion, Capacitor or Corrosion Damage · Recommended Tools