Acorn System 4 Troubleshooting Guide
The Acorn System 4 uses the same card types as the Acorn System 3 in a 14-slot rack with built-in power supplies and two disc drives.[1] Card faults are found as on the smaller systems:
- Processor card: Acorn System 1 Troubleshooting Guide for its circuit, Acorn System 2 Troubleshooting Guide for its set-up in a rack.
- VDU and memory cards: Acorn System 2 Troubleshooting Guide.
- Floppy disc controller and drives: Acorn System 3 Troubleshooting Guide.
Unplug the mains lead before opening the rack; the power supplies inside are mains units.
Narrowing down a fault
[edit | edit source]- Measure the 5 V rail at the backplane with the system running. No card has its own regulator, so a low rail affects all of them.[2]
- If the rail is low with all cards fitted, take the cards out and refit them one at a time, measuring the rail each time, to find a card that is loading it down.
- With the rail good, run with the processor, VDU and memory cards only, then add the disc controller and the other cards one by one.
Other cards
[edit | edit source]Chris Whytehead's System 4 carries an Econet card, a Universal Interface Board and a bus extender as well as the processor, RAM and VDU cards.[3] Acorn's sales sheet shows a System 4 with a cassette interface, a Versatile Interface Board, an analogue to digital converter, a PROM programmer and an in-circuit emulator.[1] When a fault appears only with one of these fitted, remove it and test the base system first.
Related pages
[edit | edit source]- Acorn System 4
- Acorn System 4 Maintenance Guide
- Acorn System 4 Capacitor Replacement Guide
- Acorn System 3 Troubleshooting Guide
References
[edit | edit source]- ↑ 1.0 1.1 Acorn Computers, Acorn System 4 Computer, one-page sales sheet, undated. Hosted on this wiki as File:Acorn System 4 brochure.pdf.
- ↑ Acorn Computers, System 2 Technical Manual, issue 1, January 1980, parts lists pp. 2-1 to 2-4 and power supply p. 5-1. Text transcription by Ben Harris, hosted on this wiki as Acorn System 2 Technical Manual (PDF).
- ↑ Whytehead, Chris. "Acorn System 4", Chris's Acorns, archived by The Centre for Computing History (retrieved 2026-10-01). Cards in Chris's System 4: 6502 CPU with System keyboard connector, 8K static RAM, 40-column VDU, Econet, Universal Interface Board, Bus Extender; no operating system ROM.