Editing Psion Organiser II General Maintenance

<templatestyles src="Template:StyledTable/styles.css" />
[[File:Psion Organiser II exploded view.png|thumb|420px|Psion's exploded assembly diagram, from the Organiser II Spare Parts List hosted here as [[:File:Psion Organiser II Spare Parts List v3.pdf]]. The numbered parts table on the same sheet gives Psion's part number for every moulding, screw and spring.]]

Preventive maintenance for the '''[[Psion Organiser II]]''' (CM, XP, LA, LZ, LZ64 and the POS variants).

The priorities are the '''PP3 battery and its compartment''', the '''pack slot contacts''', the '''conductive rubber keymat''', the '''LCD's rubber connector strip''' and — on the LZ and LZ64 particularly — the '''electrolytic capacitors on the power supply board'''.

== ⚠️ Safety ==

There are '''no mains voltages in this machine'''. It runs from a 9 V PP3 and the supply board accepts anything from '''5.5 to 11 V'''.<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]. Source for the supply range, rail descriptions, standby and running currents, PP3 characteristics, the 21 V programming voltage and the PULSE warning.</ref>

There are two things worth respecting:

* '''The programming voltage reaches 21 V''' on the SVPP rail when writing a Datapak, generated from a capacitor charged towards '''35 V'''. It will not hurt you, but it will destroy a pack or a slot device if it is applied at the wrong moment.
* Psion warn that '''damage can occur to the power supply if the PULSE signal is left enabled too long'''.<ref name="tech3" /> That matters if you are poking at the machine with your own code, not during normal use.

Everything on the system board is CMOS and surface-mount. Use an anti-static strap.

== Batteries ==

The Organiser II takes a '''9 V PP3''', and it must be a '''low-internal-resistance type''' because the machine draws peaks of 200 mA when the slots are active.<ref name="tech3" />

{| class="wikitable styled-table" style="width:75%; text-align:left;"
|+'''Battery types and what to expect'''<ref name="tech3" />
! Type !! Rechargeable !! Typical capacity !! Notes
|-
| Long-life alkaline || No || 400–500 mAh || Psion's recommendation
|-
| Nickel-cadmium || Yes || 100 mAh || Only a quarter of the runtime
|}

A new cell reads up to '''10.5 V''' off-load, and the machine keeps working down to '''5.5 V'''.<ref name="tech3" />

* '''Take the battery out for storage.''' A leaking PP3 is the commonest way these machines are destroyed, and the electrolyte creeps along the connector leads into the case. Green terminals and discoloured plastic are the giveaway.
* '''Data lives in RAM, not on the machine's own permanent storage.''' The RAM is kept alive by the standby rail, so pulling the battery for too long loses everything not saved to a pack. The supply board's hold-up capacitor is specified to keep the logic rail above 3 V for '''two to three minutes''' with the battery out, provided the machine was switched off first.<ref name="tech3" />
* '''Back up to a Datapak before any battery work.'''
* Check the '''battery connector leads and spring''' (Psion parts 8400 0006 and 8200 0002) — the leads go brittle and the moulded clip cracks.<ref name="spares">''Psion Organiser II Spare Parts List v3'', Psion. Hosted on this wiki as [[:File:Psion Organiser II Spare Parts List v3.pdf]]. Source for the part numbers, the keymat, LCD connector strip, buzzer, screws and interboard connector referenced on this page.</ref>

If a battery has already leaked, deal with the corrosion first — see [[Battery Explosion, Capacitor or Corrosion Damage]].

== Opening the machine ==

# '''Remove the battery''' and all packs.
# Remove the case screws. Psion used three sizes of self-tapper: 2 mm × 3/16 pan head (8300 0001), 2 mm × 5/16 countersunk (8300 0002) and 2 mm × 1/2 countersunk (8300 0003) — '''keep them separated'''.<ref name="spares" />
# Open the machine and lay it '''face down'''. The motherboard is screwed to the front half of the case.<ref name="bmv">Byte-My-Vdu, [https://bytemyvdu.wordpress.com/2018/12/14/psion-ii-lz-repair/ "Psion II LZ Repair"], 14 December 2018. Source for the disassembly sequence, the single screw holding the top board, the stiff keyboard ribbon and the capacitor findings.</ref>
# The '''top board is held by a single screw'''.<ref name="bmv" />
# The main logic board is still joined to the keyboard by a '''ribbon cable behind the ROM slot pins'''. It is stiff. Ease the logic board up gently — do not force it — far enough to reach the screws holding the keyboard PCB to the front case.<ref name="bmv" />
# The two boards are joined by a '''27-way strip connector''' (Psion part 4700 0004). Note its orientation before separating them.<ref name="spares" />

Photograph everything as you go. Both boards are thin and forty years old.

== The keyboard ==

The keyboard is '''PCB pads on the system board, shorted by a conductive rubber keymat''' (Psion part 8700 0001, "ORG CONDUCTIVE KEYMAT STD"), with a 36-key button set above it (2000 0048).<ref name="tech2">''Psion Organiser II Technical Manual'', Psion Ltd, 1986, Chapter 2 "System Board", transcribed at [https://www.jaapsch.net/psion/tech02.htm Jaap's Psion Organiser II Page]. Source for the keyboard construction, the 7 × 5 matrix, the AC key arrangement and the LCD connector description.</ref><ref name="spares" />

* '''Keys needing a hard press''' are dirt, not wear. Remove the keymat, wash it in warm water with a little washing-up liquid, rinse and dry completely — no heat.
* '''Clean the PCB pads''' with isopropyl alcohol on a lint-free swab. Never abrade them: the plating is thin.
* '''One dead key''' is a pad or pill problem. '''A whole row or column dead''' is a matrix line — the keys are arranged as a '''7 × 5 matrix''' with outputs K1–K7 and inputs KBD1–KBD5, so a dead row is one output and a dead column is one input.<ref name="tech2" />
* '''The AC key is not in the matrix.''' It is wired directly to the control IC and to port 5 bit 7, and it is the key that switches the machine on. If AC is dead the machine will not power up at all, however healthy everything else is.<ref name="tech2" />
* Reassemble with the keymat flat and no dust trapped underneath.

== The display ==

The LCD is driven by an '''HD44780 master and an HD44100 slave''' (HD66780 / HD66100 on the LZ), and the panel connects to the board through a '''conductive rubber connector strip''' carrying 96 connections — 16 commons and 80 segments.<ref name="tech2" /> Psion's part for the strip is '''3700 0002, "LCD. CONN. F/PITH 70 × 3.8 mm"'''; the replacement panel is '''3900 0003, "LCD LR.690-C."'''.<ref name="spares" />

* '''Missing dots, a dead column, or a faded band''' across the display is nearly always the '''rubber strip''', not the panel. Release the LCD clamp (moulding 8100 0046), lift the panel, clean both mating faces and the strip itself with isopropyl alcohol, and reassemble squarely with even clamp pressure.
* '''Even pressure matters more than force.''' The strip works by compression; over-tightening one end distorts it and makes things worse.
* '''Contrast is set by the thumbwheel''', a 10 kΩ potentiometer (VR1) on the power board, which adjusts the negative V_LCD rail between about +1.2 V and −3 V.<ref name="tech3" /><ref name="spares" /> Clean the track with switch cleaner if the wheel is gritty, and work it through its full travel.
* Never lever on the glass.

== Pack slots and the top slot ==

The two side slots and the top slot are the busiest connectors on the machine.

* '''Clean the contacts''' with a foam swab and isopropyl alcohol. Use contact cleaner sparingly and let it dry fully before fitting a pack.
* '''Keep the top port door (8100 0048) closed''' when nothing is fitted.<ref name="spares" />
* '''Never insert or remove a Rampak with the machine switched on.''' The backup cell inside has a low internal resistance, and the sudden power drop when a pack is hot-plugged causes data corruption. The same applies to switching on a hungry top-slot device.<ref name="forum">[https://www.organiser2.com/ PSION Organiser II Forum]. Community source for the Rampak hot-plug corruption problem.</ref>
* '''Rampaks have their own backup batteries.''' A Rampak that has forgotten its contents has usually just had a flat cell for years — check the cell before condemning the pack.
* '''Datapaks store data in EPROM''' and can only be erased by ultraviolet light. Keep the white light-shield label in place; a pak left in sunlight without it will slowly lose data.
* '''Deleted records still occupy space on a Datapak.''' A pak reporting itself full when it looks empty is normal behaviour, not a fault.

== The buzzer ==

The buzzer is a '''27 mm piezoelectric element''' (Psion part 4300 0003) held by its own spring (8400 0007), driven from the ALARM signal through a 1 kΩ resistor.<ref name="spares" /><ref name="tech3" />

Two things worth knowing:

* It only makes a sound '''on transitions''' of the ALARM signal, so a tone is the software toggling it. A buzzer that clicks but will not tone is a software or control-IC problem, not a dead element.
* The '''ALARM signal is also an interlock for the 21 V programming voltage'''.<ref name="tech3" /> That is not something you can adjust, but it explains why buzzer-related faults and Datapak-writing faults sometimes appear together.

== Capacitor health ==

This is the one item that genuinely deteriorates with age rather than use.

'''All the electrolytics are on the power supply board'''; the CPU board carries only chip ceramics.<ref name="spares" /> The '''LZ and LZ64 in particular develop a persistent whistle''' as those capacitors age, and a recap cures it.<ref name="bmv" />

Worth checking as maintenance rather than repair:

* '''Does the clock survive a battery change?''' It should — the hold-up is specified at two to three minutes.
* '''Does the machine whistle?'''
* '''Will it still write to a Datapak?''' Reads do not use the programming pump; writes do.

Values, designators and Psion part numbers are on the [[Psion Organiser II Capacitor Replacement Guide]].

== Case and cover ==

* The '''sliding cover''' (8100 0038) runs on a clip (8100 0043) and its spring (8400 0005).<ref name="spares" /> A weak spring lets the cover fall off in a pocket.
* '''Non-CE and CE case mouldings differ''' — Psion listed them under separate part numbers, so do not assume a donor case will fit.<ref name="spares" />
* Clean with a damp cloth only. Solvents lift the printed keyboard and display labels.

== Preventive maintenance checklist ==

# Remove the PP3 for storage; inspect the compartment, spring and connector leads for corrosion.
# Back up to a Datapak before any battery work.
# Clean both side slots and the top slot; keep the top port door closed.
# Check the contrast thumbwheel gives a full range.
# Confirm the clock survives a one-minute battery removal.
# Wash the keymat and clean the pads if any key needs a hard press.
# Verify AC switches the machine on reliably.
# Confirm a Datapak SAVE still works, not just FIND.
# Note the model and ROM version with <code>PEEKB(-24)</code> and <code>PEEKB(-23)</code> from the calculator, and write them inside the case.
# Listen for a whistle. If there is one, plan a recap.

== Recommended tools ==

* Small cross-head and jeweller's screwdrivers, plastic spudgers, an anti-static strap.
* Digital multimeter; a bench supply set to 9 V with an adjustable current limit is very useful.
* Isopropyl alcohol, lint-free swabs, contact cleaner, a fibreglass pencil.
* Fresh alkaline PP3 batteries, at least two.
* A known-good Datapak for testing.
* Temperature-controlled, earthed, '''low-power''' soldering iron, wick and leaded solder for power-board work.
* Replacement electrolytics if a recap is planned — see the capacitor guide for values.

See [[Recommended Tools]] for the general workshop kit.

== Related pages ==

* [[Psion Organiser II]]
* [[Psion Organiser II Troubleshooting Guide]]
* [[Psion Organiser II Capacitor Replacement Guide]]
* [[Psion Organiser General Maintenance]] — the Series 1
* [[Battery Explosion, Capacitor or Corrosion Damage]] · [[Recommended Tools]]

== References ==

<references />

{{Navbox-Psion}}

[[Category:Psion]]
[[Category:Maintenance Guides]]