Editing Psion Organiser Troubleshooting Guide

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[[File:Psion Organiser Series 1.jpg|thumb|360px|The Series 1. Almost every fault reported on these machines turns out to be the battery, the contrast wheel, a dirty pak contact or a dirty keymat — check those four before opening anything.]]

Fault-finding for the '''[[Psion Organiser]]''' (Series 1, 1984).

Psion published no service manual for the Series 1, but they did publish a short troubleshooting section in the user manual, and the machine's construction is well enough documented from teardown photographs to take diagnosis considerably further. Where this page relies on the [[Psion Organiser II]] Technical Manual it says so explicitly — the two power boards use the same designators and the same LM324-plus-reference-diode topology, but they are '''not proven to be identical''' and no Series 1 schematic has ever been published.

== ⚠️ Before you start ==

* '''Remove the battery before opening anything.'''
* '''Never fit a mains adaptor.''' Psion's manual states it may damage the Organiser.<ref name="p1man">''The Organiser Manual'', Psion Processors Ltd, 1984, transcribed at [https://www.jaapsch.net/psion/p1manorg.htm Jaap's Psion Organiser II Page]. Source for the manufacturer's troubleshooting procedures, the error messages, the power consumption figures, the Datapak specification and the operating limits quoted here.</ref>
* '''Never change a Datapak with the machine switched on.'''<ref name="p1man" />
* '''Do not SAVE while LOW BATTERY is showing''' — you can spoil the remaining space on the pak.<ref name="p1man" />
* Everything is CMOS. Use an anti-static strap.

== Psion's own fault procedures ==

These are the two procedures printed in the 1984 manual, and they still resolve most cases.<ref name="p1man" />

=== Blank display ===

Work through these in order until something appears:

# '''Adjust the contrast control over its full range.''' This is by far the commonest cause and it is worth doing slowly — the usable band is narrow on a tired display.
# '''Disconnect the battery, reconnect it securely and try again.'''
# '''Try a new battery.'''
# '''Remove any Datapaks and start again.'''

=== No response to the keyboard ===

If the display is fine but keys have no effect:

# '''Check you are not trying to exceed the 200-character line limit.''' The Organiser simply stops accepting input at that point, with no message.
# '''Press ON/CLEAR a few times''' and try again.
# '''Disconnect the battery, wait one minute, and reconnect it.'''

The one-minute wait matters: the power board's standby capacitor holds the logic alive for a short time after the battery is removed, and a shorter break may not clear a latched state.

== Symptom table ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Psion Organiser Series 1 — fault symptoms'''
! Symptom !! Likely cause !! Action
|-
| '''Completely dead, no display at any contrast setting''' || Flat or badly-connected battery; corroded battery leads; failed standby regulator || Measure the PP3 off-load and under load. Inspect the connector leads where they enter the compartment. A new battery reading over 9 V that still gives nothing points at the power board.
|-
| '''Display blank but machine responds (beeps, keys register)''' || Contrast set out of range; V_LCD generation failed || Sweep the thumbwheel fully both ways. If there is no change at all, the contrast circuit on the power board has failed — see the [[Psion Organiser Capacitor Replacement Guide]].
|-
| '''Display very faint or washed out at every setting''' || Ageing LCD fluid; degraded contrast circuit || Try the wheel cold and warm. A display that improves noticeably when warm is an ageing panel; one that never changes is a circuit fault.
|-
| '''Missing dots, a dead column, or half the display blank''' || Degraded LCD-to-board connection || Release the LCD clamp, clean both mating faces with isopropyl alcohol, reseat squarely and re-clamp.
|-
| '''Clock resets to 1 January every time the battery is changed''' || Standby hold-up capacitor has lost capacitance || The machine should keep time for about 15 seconds without a battery. If it cannot, the hold-up capacitor on the power board is tired.
|-
| '''Machine loses the time while sitting switched off''' || Real-time clock oscillator or standby supply marginal || Check the 32768 Hz crystal circuit. Confirm the standby rail is present with the machine off.
|-
| '''One key dead, neighbours fine''' || Dirty keymat pill or PCB pad || Clean the keymat and the gold pads. See [[Psion Organiser General Maintenance]].
|-
| '''A whole row or column of keys dead''' || Keyboard matrix line open — cracked track or dry joint || Trace the affected line. On this construction the pads are on the processor board itself, so a hairline crack in the board is a real possibility.
|-
| '''"DATAPAK ERROR" on a pak that used to work''' || Dirty slot or pak contacts; pak damaged; a write attempted at low battery || Clean both sets of contacts. Try the pak in the other slot. If it reads but will not write, the pak is probably spoiled — copy the records off it.
|-
| '''Reads paks fine but SAVE always fails''' || Programming voltage generation has failed || The write path needs a pulsed high-voltage supply from the power board; reads do not. This is the classic signature of a failed pump storage capacitor.
|-
| '''One slot works, the other does not''' || Slot contacts, or the slot's own select/supply path || Swap a known-good pak between slots to confirm, then clean; if still dead, follow the slot wiring back to the power board.
|-
| '''"DATAPAK FULL" on a pak that looks empty''' || Erased records still occupy space || EPROM cannot be electrically erased. Copy the live records to a fresh pak, or have the old one UV-formatted.
|-
| '''"NOT FOUND" when the record definitely exists''' || Search clue wrong, or aimed at the wrong slot || Check the indicator says FIND1: or FIND2: as intended. Remember a leading asterisk anchors the clue to the start of the record.
|-
| '''Typing stops having any effect''' || 200-character line limit reached || Edit the line down. This is normal behaviour, not a fault.
|-
| '''Switches itself off after a few minutes''' || Normal || The Organiser powers down after five minutes with no key pressed.
|-
| '''Runs down batteries very quickly''' || Excessive standby current; leaky capacitor; pak left drawing current || With the machine off, current should be tiny — the manual quotes 0.2 mW at 9 V, so roughly 20 µA. Anything in the milliamp range with the machine off is a fault.
|}

== Measuring the machine ==

Psion's published power figures give you a set of go/no-go checks that need nothing more than a multimeter in series with the battery.<ref name="p1man" />

{| class="wikitable styled-table" style="width:85%; text-align:left;"
|+'''Expected supply current at 9 V, derived from Psion's published power figures'''
! State !! Published power !! Approximate current
|-
| Machine off || 0.2 mW || ~20 µA
|-
| Machine on, idle || 40 mW || ~4.4 mA
|-
| Datapak access, one pak || 500 mW || ~55 mA
|-
| Datapak access, two paks || 800 mW || ~90 mA
|}

Interpretation:

* '''Off-state current in the milliamps''' means something is leaking. A shorted or very leaky electrolytic on the power board is the usual culprit, and it explains batteries that go flat in storage.
* '''On-state current far above 5 mA with no pak activity''' suggests a supply rail that is not regulating.
* '''Little or no current rise during SAVE''' means the programming voltage is never being generated — consistent with reads working and writes failing.
* '''A dead short''' (current limits immediately) is usually a tantalum or electrolytic that has failed short.

Use a bench supply set to 9 V with the current limit wound down to about 100 mA in place of the battery. It will catch a shorted rail before it damages anything else.

== Understanding the power board ==

Psion never documented the Series 1 power board. However, the board is silkscreened with the same designator set — C1, C3, C5, C6, C8, C9, C10, RD1, ZN1, VR1 — and carries the same '''LM324''' quad op-amp and reference diode arrangement that Psion described in detail for the [[Psion Organiser II]].<ref name="galp1">[https://www.jaapsch.net/psion/galp1.htm Psion Organiser Series 1 Image Gallery], Jaap's Psion Organiser II Page. Source for the board legends, device markings and construction.</ref><ref name="tech3">''Psion Organiser II Technical Manual'', Psion Ltd, 1986, Chapter 3 "Power Supply Board", transcribed at [https://www.jaapsch.net/psion/tech03.htm Jaap's Psion Organiser II Page]. Used here only as an analogue for the Series 1 board, whose circuit Psion never published.</ref>

On the Organiser II board those parts do the following, and the same functional blocks are visible on the Series 1 board:<ref name="tech3" />

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Power supply functions (documented for the Organiser II; the Series 1 board appears to be the same design family)'''
! Function !! What it does !! Symptom when it fails
|-
| '''Standby regulator''' || Keeps the logic and clock alive at 3–5 V while the machine is off, at roughly 30 µA || Machine forgets the time whenever it is switched off, or loses everything on a battery change
|-
| '''Standby hold-up capacitor''' || Supports the rail for '''2–3 minutes''' with the battery removed, provided the machine is off || Clock resets on every battery change
|-
| '''Main 5 V regulator''' || Regulates the logic rail to 5 V ±5 % once the machine is switched on || Erratic operation, crashes, garbage on the display
|-
| '''V_LCD generator''' || A charge pump driven from a 1 kHz square wave, adjusted by the thumbwheel, producing roughly +1.2 V to −3 V for display contrast || No contrast control, blank or washed-out display
|-
| '''Programming voltage pump''' || Charges a storage capacitor to about 35 V through an inductor, then regulates it to '''21 V''' in pulses to program Datapak EPROM || Datapaks read but will not write
|-
| '''Low-battery detector''' || Sets a LOWBAT flag when the logic rail falls about 2 % below nominal || Persistent LOW BATTERY with a good cell, or no warning at all with a flat one
|}

'''Treat this as a map, not a schematic.''' Confirm the function of a part on your own board before replacing it.

== When the machine is genuinely beyond the power board ==

* '''Processor board faults are effectively unrepairable at component level.''' Everything on it is surface-mount and the CPU's firmware is masked into the die — an HD6301X0F from another machine will not carry the Organiser code.
* '''The HD44780 LCD controller''' is a common part and can in principle be replaced, but it is a fine-pitch flat pack on a delicate board.
* '''The discrete CMOS logic''' (HEF4011, HEF4013, HEF4040, HEF4060, HEF4081) is all still obtainable in SMD, so a single failed gate package is a realistic repair for someone equipped for surface-mount work.
* Because the Series 1 processor board carries the keyboard pads on its reverse, '''a cracked board can present as a keyboard fault''' — inspect it under good light before condemning the keymat.

== Related pages ==

* [[Psion Organiser]]
* [[Psion Organiser General Maintenance]]
* [[Psion Organiser Capacitor Replacement Guide]]
* [[Psion Organiser II Troubleshooting Guide]] — the better-documented successor
* [[Battery Explosion, Capacitor or Corrosion Damage]] · [[Capacitor Failure Symptoms]]

== References ==

<references />

{{Navbox-Psion}}

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