Psion Organiser Troubleshooting Guide

The Psion Organiser Series 1

Fault-finding for the Psion Organiser (Series 1, 1984). Psion published no service manual or schematic for the Series 1. The user manual has a short troubleshooting section, the board construction is known from teardown photographs, and the Psion Organiser II Technical Manual documents a power supply board built on the same scheme: an LM324 op-amp regulator with reference diode RD1, zener ZN1, contrast control VR1 and capacitors at C1, C3, C6 and C8. Figures taken from the Organiser II manual are marked as such below; confirm the function of a part on the Series 1 board before replacing it.

Preliminary checks

• Remove the battery before opening the machine.
• Do not fit a mains adaptor. Psion's manual says it may damage the Organiser.
• Switch off before changing a Datapak.
• Do not SAVE while LOW BATTERY is showing.
• The processor board is CMOS throughout. Use an anti-static strap.

Check the battery, the contrast wheel, the pak contacts and the keymat before opening the case. Psion's own procedures for a blank display and an unresponsive keyboard cover the first three.

Power and battery faults

Power and battery symptoms

Symptom	Probable cause	Action
Dead, no display at any contrast setting	Flat or badly connected battery; corroded battery leads; power board fault	Measure the PP3 off-load and under load. Inspect the leads where they enter the compartment. A fresh battery that still gives nothing points at the power board.
Clock restarts from midnight on 31 December after every battery change	Battery left out for more than fifteen seconds, or the standby hold-up on the power board has failed	Psion specifies fifteen seconds of clock hold-up with the machine switched off. If a quick swap still loses the time, check the power board electrolytics.
Loses the time while switched off with a good battery	Standby supply or 32768 Hz clock oscillator	Confirm the standby rail is present with the machine off, then check the crystal circuit on the processor board.
Switches itself off after five minutes	Normal behaviour	The Organiser switches off after five minutes with no key pressed.
Flattens batteries quickly	Excessive standby current	Measure the off-state current (see below). Anything in the milliamp range with the machine off is a fault.

Measuring supply current

Psion's published power figures give go/no-go checks with a multimeter in series with the battery. The currents are the published power divided by 9 V.

Expected supply current at 9 V

State	Published power	Approximate current
Machine off	0.2 mW	22 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

• Off-state current in the milliamps means something is leaking; check the electrolytics on the power board first.
• On-state current well above 5 mA with no pak activity suggests a rail that is not regulating.
• No rise in current during SAVE means the programming voltage is not being generated, which matches paks that read but will not write.
• A current that hits the limit immediately is a short on a rail.

A bench supply set to 9 V with the current limit at about 100 mA can stand in for the battery while measuring, and limits the damage from a shorted rail.

Power supply board functions

Psion documented the Organiser II power supply board but not the Series 1 board. The Organiser II blocks below are the nearest published description of what the Series 1 parts do. The Series 1's own clock hold-up figure is fifteen seconds, not the Organiser II's two to three minutes.

Organiser II power supply functions (Technical Manual chapter 3)

Function	Organiser II specification	Symptom when it fails
Standby regulator	Holds the logic rail at 3–5 V while the machine is off, at a typical load of 30 µA	Loses the time whenever it is switched off
Standby hold-up capacitor (C3)	Holds the logic rail above 3 V for 2–3 minutes with the battery removed, provided the machine is off	Clock resets on every battery change
Main 5 V regulator (LM324 section and RD1)	Regulates the logic rail to 5 V ±5 % when the machine is on	Erratic operation, crashes, corrupt display
V_LCD generator (C8, D3, C1, VR1)	Charge pump driven by a 1024 Hz square wave, adjusted by the thumbwheel between +1.2 V and −3 V	No contrast control; blank or washed-out display
Programming voltage pump (L1, ZN1, C6)	Charges C6 to about 35 V, then regulates to 21 V in pulses to program Datapak EPROM	Paks read but will not write
Low-battery detector	Signals LOWBAT when the logic rail falls about 2 % below nominal	LOW BATTERY with a good cell, or no warning with a flat one

Display faults

Psion's procedure for a blank display, in order, stopping when something appears:

1. Adjust the contrast control over its full range.
2. Disconnect the battery, reconnect it securely and try again.
3. Try a new battery.
4. Remove any Datapaks and start again.

Display symptoms

Symptom	Probable cause	Action
Blank display but keys register	Contrast out of range; contrast voltage not generated	Sweep the thumbwheel fully both ways. If nothing changes at any setting, check the contrast circuit and its capacitors on the power board.
Missing dots, a dead column or half the display blank	Poor connection between the LCD module and the board	Release the LCD clamp, clean both mating faces with isopropyl alcohol, and reseat squarely.

Keyboard faults

Psion's procedure when the display is normal but the keys have no effect:

1. Check that the line is not already at the 200-character limit. The Organiser stops accepting input at that point.
2. Press ON/CLEAR a few times and try again.
3. Disconnect the battery, wait one minute, and reconnect it.

Keyboard symptoms

Symptom	Probable cause	Action
One key dead, neighbours fine	Dirty keymat pill or PCB pad	Clean the keymat and the gold pads. See Psion Organiser General Maintenance.
A group of keys dead	Open keyboard matrix line: cracked track or dry joint	Trace the affected line. The pads are on the reverse of the processor board, so inspect the board for cracks under good light.
Typing stops having any effect	200-character line limit reached	Normal behaviour. Shorten the line.

Datapak faults

Datapak symptoms

Symptom	Probable cause	Action
DATAPAK ERROR on a pak that used to work	Dirty slot or pak contacts; damaged pak; a SAVE attempted at low battery	Clean both sets of contacts and try the pak in the other slot. If records can still be found but no more can be saved, copy them to another pak and reclaim the old one in a Psion Formatter.
Paks read but SAVE always fails	Programming voltage not generated	Writing needs the programming supply from the power board and reading does not. On the Organiser II this is the pump built around L1, ZN1 and C6. Check the corresponding parts and capacitors on the Series 1 board.
One slot works, the other does not	Slot contacts, or that slot's supply or select path	Swap a known-good pak between the slots to confirm, clean the contacts, then follow the slot wiring back to the power board.
DATAPAK FULL on a pak that seems nearly empty	Erased records still occupy space	EPROM cannot be erased electrically. Copy the live records to a fresh pak, or UV-format the old one.
NOT FOUND when the record exists	Wrong search clue, or the wrong slot	Check that the indicator shows FIND1: or FIND2: as intended. A leading asterisk anchors the clue to the start of the record.

Copying records off a failing pak and formatting it in the Psion Formatter are covered in Psion Organiser Datapak Repair.

Processor board faults

• The processor board is surface-mount throughout. The firmware is masked into the HD6301X0F CPU, so a replacement CPU has to come from another Series 1.
• The HD44780 LCD controller is a standard Hitachi part but a fine-pitch flat pack.
• The glue logic (HEF4011BT, HEF4013BT, HEF4040BT, HEF4060BT and HEF4081BT) is standard 4000-series CMOS in SMD packages, so a single failed package can be replaced by anyone equipped for surface-mount work.
• The keyboard pads are on the reverse of the processor board, so a cracked board can show up as a keyboard fault.

Related pages

• Psion Organiser
• Psion Organiser General Maintenance
• Psion Organiser Capacitor Replacement Guide
• Psion Organiser Datapak Repair
• Psion Organiser II Troubleshooting Guide
• Battery Explosion, Capacitor or Corrosion Damage
• Capacitor Failure Symptoms