Psion Revo General Maintenance

Preventive maintenance for the Psion Revo (and, with the differences noted, the Psion Revo Plus and Diamond Mako).

The Revo's maintenance story is its battery. Unlike every other EPOC Psion, you cannot change the cells in the field: they are two NiMH AAA cells soldered to a connector and sealed under the nameplate.^[1]

⚠️ Charging rules

These are the habits that determine how long a Revo's cells last, and they are unusual enough to be worth learning deliberately.

Do not put the machine on charge when the battery is already above about 80 %. The charge termination depends on sensing a thermal change that occurs around that level. Missing that thermal change can and does lead to overcharging.^[1]
NiMH cells only. Because of the way the charging circuit works, no other chemistry is recommended.^[1]
The red charging light turns off at around 84 %, not at 100 %. That is normal; it does not mean charging has finished.^[1]
After any cell replacement, and after a hard reset, charge uninterrupted from 0 % to 100 % — about six hours for stock 700 mAh capacity, preferably with the machine switched off — so the hardware can recalibrate. Ignore the battery meter during that first charge.^[1]

Put plainly: let it run down properly before charging, and let the charge finish. Topping a Revo up constantly is the worst thing you can do to it.

The loose battery connector

Original Revos suffer from batteries coming loose and unplugging inside the case. Psion fixed this on the Revo Plus.^[1]

That means an original Revo which dies intermittently, refuses to charge, or resets for no reason may have nothing wrong with it electrically — the connector may simply have worked loose. If you are in the machine for any reason, put a small dab of hot-melt glue or silicone over the battery connector to hold it. Not superglue — you will want to disconnect it again one day.^[2]

The case microswitch

A microswitch on the rear turns the Revo on and off as the case is opened and closed, and it is easily broken by too much force when refitting the battery bay.^[2]

Treat it as the most fragile thing in the machine after the screen. A Revo that no longer wakes on opening, or no longer sleeps on closing, has usually lost this switch to a previous repair.

Backups

There is no CompactFlash slot, so the only routes off the machine are the serial link through the docking station and IrDA.^[1]

Keep the docking station and its cable with the machine.
Back up before any work — opening a Revo to replace the cells factory resets it.^[2]
Keep the IrDA window clean; it is the only wireless route.

Screen and case

The screen is 480 × 160 with no backlight.^[1] A Revo that seems dim in poor light is behaving normally.
Use a proper stylus on the resistive touchscreen, not a fingernail or a pen.
The screen ribbon connector has a restraint that flips up; with it lifted the ribbon needs no force to insert or remove. If it resists, the restraint is not properly released — do not force it.^[2]
Prising the screen from its surround with too much force will shatter it.^[2]
The nameplate is glued. If it is ever off, refit it with hot-melt glue, not superglue.^[2]

Capacitors

Not a recap candidate. The Revo is a 1999 low-voltage surface-mount design of the same generation and construction as the 5mx. Its faults are the battery, the charging circuit's calibration, the case microswitch and physical damage — none of which is a capacitor.

For the small number of situations where capacitor work is justified on a board of this type, see Psion Series 5mx Capacitor Replacement Guide.

Preventive maintenance checklist

Back up through the dock or IrDA.
Let the battery run down before charging, and let the charge complete.
Do not leave it on charge above 80 %.
If the runtime has collapsed, plan a cell replacement — see Psion Revo Battery Replacement.
On an original Revo, secure the battery connector with hot-melt glue if you are ever inside the case.
Check the rear case microswitch still wakes and sleeps the machine.
Clean the IrDA window, the serial connector and the dock contacts.
Clean the touchscreen with a soft dry cloth.

Recommended tools

Scalpel or watchmaker's knife, jeweller's screwdrivers, small flat screwdriver.
Dental floss for lifting the nameplate without bending it.^[2]
Fine-tipped soldering iron, heatshrink or tape, hot-melt glue gun or silicone sealer.
NiMH AAA cells with solder tags when the time comes.
The docking station and cable.

See Recommended Tools for the general workshop kit.

Related pages

References

↑ ^1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 ^1.7 "Psion Revo", Wikipedia. Source for the built-in cell arrangement, the battery notoriety, the loose-battery problem and its fix in the Plus, the NiMH-only requirement, the over-80 % charging caution, the recalibration charge and the 84 % charging-light behaviour.
↑ ^2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 David Savery, "Psion Revo/Diamond Mako Disassembly & Battery Replacement", R3UK, 2004. Source for the glue guidance, the microswitch warning, the thermistor, the pack construction, the screen ribbon restraint and the disassembly cautions.

[wprevo-1] 1.0 ^1.1 ^1.2 ^1.3 ^1.4 ^1.5 ^1.6 ^1.7 "Psion Revo", Wikipedia. Source for the built-in cell arrangement, the battery notoriety, the loose-battery problem and its fix in the Plus, the NiMH-only requirement, the over-80 % charging caution, the recalibration charge and the 84 % charging-light behaviour.

[r3uk-2] 2.0 ^2.1 ^2.2 ^2.3 ^2.4 ^2.5 ^2.6 David Savery, "Psion Revo/Diamond Mako Disassembly & Battery Replacement", R3UK, 2004. Source for the glue guidance, the microswitch warning, the thermistor, the pack construction, the screen ribbon restraint and the disassembly cautions.

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