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Psion Organiser II General Maintenance

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Psion Organiser II exploded view
Psion's exploded assembly diagram from the Organiser II Spare Parts List, with Psion part numbers for each moulding, screw and spring

Routine care of the Psion Organiser II (CM, XP, LA, LZ, LZ64 and the POS variants) covers the PP3 battery and its compartment, the pack slot contacts, the conductive rubber keymat, the LCD's rubber connector strips and the electrolytic capacitors on the power supply board. Psion's Organiser II Spare Parts List gives part numbers for every moulding, screw and spring referred to below.[1]

There is no mains voltage in the machine. It runs from a 9 V PP3, and the power supply board accepts 5.5 to 11 V.[2] When a Datapak is written, the SVPP rail to the side slots rises to 21 V, generated from a capacitor charged to about 35 V. The Technical Manual warns that the power supply can be damaged if the PULSE signal that drives this pump is left enabled for too long; that is a concern for anyone running their own machine code, not in normal use.[3][2] The system board is CMOS throughout, so use an anti-static strap.[3]

Regular cleaning

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Case and cover

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  • Clean the case with a damp cloth.
  • The sliding cover (8100 0038) is held by a clip (8100 0043) and its spring (8400 0005). A weak spring lets the cover fall off.[1]
  • Psion listed CE and non-CE case mouldings under separate part numbers, so check the listing before buying a donor case.[1]

Keyboard

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The keyboard is PCB pads on the system board shorted by a conductive rubber keymat (8700 0001, "ORG CONDUCTIVE KEYMAT STD"), with a 36-key button set above it (2000 0048).[3][1]

  • A key that needs a hard press usually has dirt on the mat or pad. Remove the keymat, wash it in warm water with a little washing-up liquid, rinse and let it dry completely without heat.
  • Clean the PCB pads with isopropyl alcohol on a lint-free swab. Do not abrade them: the plating is thin.
  • One dead key is a pad or keymat fault. The other 35 keys form a 7 × 5 matrix with outputs K1–K7 and inputs KBD1–KBD5, so a dead row is one output line and a dead column is one input line.[3]
  • The ON/CLEAR key (AC in the Technical Manual) is not in the matrix. It is wired directly to the control IC and to port 5 bit 7, and is the key that switches the machine on, so a dead ON/CLEAR key leaves the machine impossible to switch on from the keyboard.[3]
  • Seat the keymat flat with no dust trapped underneath.

Display

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The LCD is driven by an HD44780 master and HD44100 slave (HD66780 and HD66100 on the LZ). The panel connects to the board through conductive rubber connector strips carrying 96 connections: 16 commons and 80 segments.[3][1] Psion's part for the strip is 3700 0002, "LCD. CONN. F/PITH 70*3.8mm", and the replacement two-line panel is 3900 0003, "LCD LR.690-C.".[1]

  • If dots, a column or a band of the display are missing, release the LCD clamp (8100 0046), lift the panel, clean both mating faces and the strip with isopropyl alcohol, and reassemble squarely with even clamp pressure before condemning the panel.[1]
  • Contrast is set by the thumbwheel, a 10 kΩ potentiometer (VR1) on the power supply board, which adjusts the negative V_LCD rail between +1.2 V and −3 V.[2][1] If the wheel is gritty, apply a little switch cleaner and work it through its full travel.
  • Do not lever on the glass.

Disassembly

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  1. Remove the battery and all packs.
  2. 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.[1]
  3. Open the machine and lay it face down. The main board is screwed to the front half of the case.[4]
  4. Remove the single screw holding the top board.[4]
  5. The main logic board is still joined to the keyboard by a stiff ribbon cable behind the pack slot pins. Ease the logic board up gently, far enough to reach the screws holding the keyboard PCB to the front case.[4]
  6. The system board and power supply board are joined by a 27-way strip connector (4700 0004). Note its orientation before separating them.[3][1]

Photograph each stage before separating anything.

Battery and power checks

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The Organiser II takes a 9 V PP3. It must have a low internal resistance, because the machine draws peaks of 200 mA when the slots are active.[2] Psion's manual specifies a standard alkaline long-life battery.[5]

PP3 types[2]
Type Rechargeable Typical capacity
Long-life alkaline No 400–500 mAh
Nickel-cadmium Yes 100 mAh between charges

A new cell reads up to 10.5 V off-load, and the machine keeps working down to 5.5 V.[2]

  • The internal memory (device A:) depends on the battery. Back up to a Datapak before any battery work.[5]
  • Change the battery with the machine switched off and fit the new one within 90 seconds, or the contents of the internal memory are lost. A Psion mains adaptor can power the machine while the battery is changed.[5] The Technical Manual gives the design hold-up of the standby rail as two to three minutes with the machine off.[2]
  • Take the battery out for storage, and inspect the compartment, the battery connector spring (8400 0006) and the contact terminals (8200 0002) for corrosion.[1] If a battery has already leaked, deal with the corrosion first; see Battery Explosion, Capacitor or Corrosion Damage.

Pack slots and the top slot

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  • Clean the side-slot and top-slot contacts with a foam swab and isopropyl alcohol. If contact cleaner is used, let it dry fully before fitting a pack.
  • Keep the top port door (8100 0048) closed when nothing is fitted.[1]
  • Fit and remove packs with the machine face down on a flat surface. The keyboard is slightly recessed, so no key is pressed by accident.[5]
  • Switch the Organiser off before inserting or removing a Rampak. Psion's leaflet says that otherwise all the information in the Rampak will be lost, and the Rampak or the Organiser may be damaged.[6]
  • The 32 KB Rampak's built-in battery has a life of about five years, so an old Rampak that has lost its contents probably has a flat cell.[6]
  • Keep the white label on the underside of each Datapak in place. It protects the EPROM from excessive exposure to light and is removed only for formatting.[5]
  • Erased records still occupy space on a Datapak, so a pak that reports itself full when it seems nearly empty is behaving normally. Copying the live records to a fresh pak leaves the erased ones behind.[5]

Pack error messages, formatting Datapaks and Flashpaks, and the Rampak's backup cell are covered in Psion Organiser II Datapak Repair.

Capacitors

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In Psion's Spare Parts List the electrolytic capacitors are on the power supply board; the CPU board lists show chip capacitors only.[1] On the LZ and LZ64 an ageing capacitor causes a persistent whistle, and replacing the electrolytics has cured it.[4]

Signs that the capacitors need attention:

  • The clock or internal memory is lost on a quick battery change with the machine off.
  • The machine whistles.
  • Datapaks read but will not write. Only writing uses the programming pump.[2]

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

Buzzer

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The buzzer is a 27 mm piezoelectric element (4300 0003) held by its own spring (8400 0007), driven from the ALARM signal through a 1 kΩ resistor.[1][2] It sounds only on transitions of ALARM, so tones are produced by the software toggling the signal. ALARM is also an interlock for the 21 V programming voltage.[3][2]

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

See Recommended Tools for the general workshop kit.

Preventive maintenance checklist

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  1. Back up the internal memory to a Datapak.
  2. Remove the PP3 for storage; inspect the compartment, spring and contacts for corrosion.
  3. Clean both side slots and the top slot; keep the top port door closed.
  4. Check that the contrast thumbwheel gives a full range.
  5. Wash the keymat and clean the pads if any key needs a hard press.
  6. Check that ON/CLEAR switches the machine on reliably.
  7. Check that a Datapak SAVE works as well as FIND.
  8. Note the model and ROM version with PEEKB(-24) and PEEKB(-23) from the calculator.[7]
  9. Listen for a whistle. If there is one, plan a recap.
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References

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  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 Psion, Organiser II Spare Parts List, version 3: exploded view parts table, power supply board and CPU board lists. Hosted on this wiki as File:Psion Organiser II Spare Parts List v3.pdf.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 Psion Organiser II Technical Manual, Psion Ltd, 1986, chapter 3 "Power Supply Board", sections 3.1–3.4, 3.7–3.9 and 3.11, transcribed at Jaap's Psion Organiser II Page.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 Psion Organiser II Technical Manual, Psion Ltd, 1986, chapter 2 "System Board", sections 2.1, 2.2, 2.5 and 2.6, transcribed at Jaap's Psion Organiser II Page.
  4. ↑ 4.0 4.1 4.2 4.3 Byte-My-Vdu, "Psion II LZ Repair", 14 December 2018, and the author's follow-up comment confirming the recap cured the whistle.
  5. ↑ 5.0 5.1 5.2 5.3 5.4 5.5 Psion PLC, Psion Organiser II Operating Manual (CM/XP), V1, January 1989, part no. 6100-0024: "Fitting Datapaks", "Re-using a Datapak", chapter 10 "Replacing the battery" and appendix B "Technical data". Transcribed at Jaap's Psion Organiser II Page.
  6. ↑ 6.0 6.1 Psion, 32K Rampak Instruction Leaflet, transcribed at Jaap's Psion Organiser II Page.
  7. ↑ "Psion Organiser II Models and Version Numbers", Jaap's Psion Organiser II Page.


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