Editing Psion Revo Troubleshooting Guide

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[[File:Psion Revo.jpg|thumb|420px|A Psion Revo. Diagnose the battery and its connector before anything else — on this machine they account for the overwhelming majority of faults.]]

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.<ref name="wprevo">[https://en.wikipedia.org/wiki/Psion_Revo "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.</ref>

== ⚠️ 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'''.<ref name="r3uk">David Savery, [https://www.r3uk.com/index.php/tech-tips/34-disassembly-guides/3-psion-revodiamond-mako-disassembly-and-battery-replacement "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.</ref>
* '''There is not a millimetre to spare inside a Revo.''' It is an awkward machine to work on and disassembly is risky.<ref name="r3uk" />

== Step 1: battery and charging ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''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 [[Psion Revo Plus|Plus]]''' || Open the machine and secure the connector with hot-melt glue or silicone. Not superglue.<ref name="wprevo" /><ref name="r3uk" />
|-
| '''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.'''<ref name="wprevo" />
|-
| '''Red charging light goes out well before full''' || '''Normal.''' It turns off at around '''84 %''' || Not a fault.<ref name="wprevo" />
|-
| '''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 %.'''<ref name="wprevo" />
|-
| '''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.<ref name="r3uk" /><ref name="wprevo" />
|-
| '''Replaced cells behave oddly''' || Wrong chemistry || '''NiMH only.''' The charging circuit is designed around it.<ref name="wprevo" />
|-
| '''Fitted higher-capacity cells and the charge seems short''' || Expected || Work out and extend the charge time proportionally.<ref name="wprevo" />
|}

== 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.<ref name="r3uk" />

{| class="wikitable styled-table" style="width:100%; text-align:left;"
! 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.<ref name="r3uk" />
|-
| '''Machine will not open or close properly after a repair''' || '''The battery pack is not seated correctly.''' Check this before suspecting the hinges.<ref name="r3uk" />
|}

== Step 3: things that are not faults ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Deliberate omissions'''<ref name="wprevo" />
! 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.<ref name="r3uk" />

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

== Step 4: screen and connectivity ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
! 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.<ref name="r3uk" />
|-
| '''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.<ref name="r3uk" />
|-
| '''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.<ref name="spec">[https://www.psion.netogram.com/psionspecifications.html "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.</ref>
|-
| '''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 [[Psion Series 5mx|5mx]], and is software compatible with it.<ref name="wprevo" />

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 ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
! 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 ==

<references />

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[[Category:Psion]]
[[Category:Troubleshooting Guides]]