Psion Revo Troubleshooting Guide

Fault-finding for the Psion Revo (and, with the differences noted, the Psion Revo Plus and Diamond Mako).

Start with the battery. The Revo was notorious for battery and charging problems, and after twenty-five years the cells in an untouched machine are certainly worn out.^[1]

⚠️ Before you start

Back up through the dock or IrDA first. There is no card slot, and opening the machine to reach the cells factory resets it.^[2]
There is not a millimetre to spare inside a Revo. It is an awkward machine to work on and disassembly is risky.^[2]

Step 1: battery and charging

**Battery and charging faults**
Symptom	Cause	Action
Runtime collapsed; will not hold a charge	Worn NiMH cells. Original stock is 700 mAh and dates from 1999–2003	Replace them. See Psion Revo Battery Replacement.
Dies intermittently; resets for no reason; will not charge	The battery connector working loose. Original Revos suffer from batteries coming loose and unplugging — fixed on the Plus	Open the machine and secure the connector with hot-melt glue or silicone. Not superglue.^[1]^[2]
Battery meter obviously wrong	The hardware has not been recalibrated	Hard reset, then charge uninterrupted from 0 % to 100 % — about six hours at stock capacity, preferably switched off. Ignore the meter during that charge.^[1]
Red charging light goes out well before full	Normal. It turns off at around 84 %	Not a fault.^[1]
Cells get hot; charge never terminates	Overcharging. Charge termination senses a thermal change around 80 %; if the machine is put on charge above that level the change is missed	Do not charge either Revo model when the battery is already above about 80 %.^[1]
Charges erratically after a cell replacement	Damaged thermistor. A strip of circuit ribbon wrapped in with the cells acts as the temperature sensor	It must be intact and held against the cell body. Rewrap the pack correctly.^[2]^[1]
Replaced cells behave oddly	Wrong chemistry	NiMH only. The charging circuit is designed around it.^[1]
Fitted higher-capacity cells and the charge seems short	Expected	Work out and extend the charge time proportionally.^[1]

Step 2: the case microswitch

A microswitch on the rear switches the Revo on and off as the case is opened and closed. It is easily broken by too much force when refitting the battery bay — which means it is very often broken on a machine that has already been opened once.^[2]

Symptom	Assessment
Does not wake on opening, or does not sleep on closing	Broken or displaced case microswitch. Frequently the legacy of a previous battery replacement.^[2]
Machine will not open or close properly after a repair	The battery pack is not seated correctly. Check this before suspecting the hinges.^[2]

Step 3: things that are not faults

**Deliberate omissions**^[1]
Reported as	Assessment
No backlight	Correct. The Revo was built without one.
No CompactFlash or card slot	Correct. The Revo has none. Data moves by the docking station or IrDA.
Screen smaller than a 5mx	Correct. 480 × 160 against the 5mx's 640 × 240.
Cannot change the batteries	Correct. They are soldered in and sealed under the nameplate.

The backlight story

There is a persistent claim that Psion left the backlight wiring in place and omitted only the lamps. Pads marked EL+ and EL− do exist under black tape on the screen PCB — but a voltmeter across them gave no reading, AC or DC, with the unit on and with the Fn + Space sequence that works on a Series 5.^[2]

Fitting a backlight to a Revo has not been shown to work.

Step 4: screen and connectivity

Symptom	Cause	Action
Screen ribbon will not come out	The connector restraint is not properly lifted	With the restraint up the ribbon needs no force. Do not force it — lift the restraint properly.^[2]
Screen cracked during disassembly	Too much pressure prising it from the surround	Start unclipping at the bottom and work up the sides, gently. The rear of the screen is metal-encased and tolerates gentle levering; the glass does not.^[2]
No serial connection	Dock contacts, cable, or baud rate	The Revo does RS-232 on a 9-pin D-sub at up to 115,200 bit/s, through the docking station.^[3]
IrDA transfers fail	Dirty or scratched window; misalignment	Clean it. IrDA needs line of sight at both ends.
Touchscreen inaccurate	Calibration lost after a total power loss	Recalibrate through the operating system, as on any EPOC machine.

Step 5: the shared EPOC material

The Revo runs the same 36 MHz ARM710T and the same Symbian (EPOC32) Release 5 as the 5mx, and is software compatible with it.^[1]

For the reset levels, the Battery Information screen at Shift-Ctrl-P, the touchscreen calibration behaviour and general EPOC diagnosis, see Psion Series 5mx Troubleshooting Guide.

What does not carry over is anything to do with the 5mx's case: the Revo has no sliding keyboard, no spring hinge wires and no CompactFlash door, so those faults do not exist here.

What is realistically repairable

Part	Repairable?	Notes
Battery pack	Yes	The standard job. See Psion Revo Battery Replacement.
Battery connector	Yes	Reseat and glue.
Case microswitch	Difficult	Small, fragile, and easily lost during a repair.
Screen	With a donor	Very easily shattered during removal.
Mainboard	Board-level swap only	Dense surface-mount construction.

Related pages

Psion Revo · Psion Revo General Maintenance · Psion Revo Battery Replacement
Psion Revo Plus Troubleshooting Guide
Psion Series 5mx Troubleshooting Guide — the shared EPOC diagnostics
Battery Refurbishment · Recommended Tools

References

↑ ^1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 "Psion Revo", Wikipedia. Source for the battery notoriety, the cell specification, the loose-battery problem and its fix in the Plus, the NiMH-only requirement, the over-80 % charging caution, the recalibration charge, the 84 % charging-light behaviour, and the machine's omissions relative to the 5mx.
↑ ^2.00 ^2.01 ^2.02 ^2.03 ^2.04 ^2.05 ^2.06 ^2.07 ^2.08 ^2.09 David Savery, "Psion Revo/Diamond Mako Disassembly & Battery Replacement", R3UK, 2004. Source for the factory reset warning, the disassembly procedure, the thermistor, the case microswitch, the screen ribbon restraint and the EL pad measurements.
↑ "Psion 3mx, Psion 5, Psion 5mx, Psion Revo and Psion Revo Plus specifications", netogram.com. Source for the Revo interfaces, docking station, run time and power adapter rating.

[wprevo-1] 1.00 ^1.01 ^1.02 ^1.03 ^1.04 ^1.05 ^1.06 ^1.07 ^1.08 ^1.09 "Psion Revo", Wikipedia. Source for the battery notoriety, the cell specification, the loose-battery problem and its fix in the Plus, the NiMH-only requirement, the over-80 % charging caution, the recalibration charge, the 84 % charging-light behaviour, and the machine's omissions relative to the 5mx.

[r3uk-2] 2.00 ^2.01 ^2.02 ^2.03 ^2.04 ^2.05 ^2.06 ^2.07 ^2.08 ^2.09 David Savery, "Psion Revo/Diamond Mako Disassembly & Battery Replacement", R3UK, 2004. Source for the factory reset warning, the disassembly procedure, the thermistor, the case microswitch, the screen ribbon restraint and the EL pad measurements.

[spec-3] "Psion 3mx, Psion 5, Psion 5mx, Psion Revo and Psion Revo Plus specifications", netogram.com. Source for the Revo interfaces, docking station, run time and power adapter rating.

[1]

[2]

[3]