Sinclair ZX Spectrum Service Manual
The Sinclair ZX Spectrum Service Manual is Sinclair Research's service manual for the 16K and 48K Sinclair ZX Spectrum and the Sinclair ZX Spectrum+. The copy hosted here is Revision 1.3 of a re-typeset edition edited by Brendan Alford for the Spectrum For Everyone website, 60 pages. It combines the original manual, which covers board Issues 1 to 3B, with Sinclair's Supplement No. 1 (Issues 4A, 4B, 5 and 6A) and Supplement No. 2 (the Spectrum+ conversion and keyboard). It is written at component level, with a separate parts list for each group of board issues.
The original March 1984 edition, prepared by Thorn (EMI) Datatech Ltd for Sinclair Research with T.I.S. Service Data and Repair Data sections appended, is hosted separately as ZX Spectrum Servicing Manual (Thorn EMI Datatech, 1984).
Contents
[edit | edit source]| Section | Title and main subsections | Pages |
|---|---|---|
| 1 | Introduction: architecture, Z80A CPU, memory organisation, read/write operations, input/output, TV picture generation, keyboard scanning (1.8), tape interface, loudspeaker, power supplies (1.11) | 7–15 |
| 2 | Disassembly/assembly | 16 |
| 3 | Setting up and system test: voltage check (3.1.2), colour adjustment, sub-carrier oscillator, 14 MHz oscillator, system test | 17–19 |
| 4 | Fault diagnosis and repair – getting started: test equipment, modification history, modifications to the Issue 1, 2 and 3B boards, 32K extension memory, Hitachi vs NEC ROM | 20–24 |
| 5 | Fault diagnosis and repair – PSU and memory: techniques, power supply unit (5.2), basic checks (5.3.1), memory check and the RAM bit-to-IC table (5.4), keyboard structure (5.5) | 25–29 |
| 6 | Fault diagnosis and repair – input/output: TR4 faults, no video, corrupt paper, video incorrect, colour faults, keyboard faults, regulator coil, speaker | 30–35 |
| 7 | Fault diagnosis and repair – colour, repair and upgrades: IC14 (LM1889) pin signals, repair notes (7.2), 16K to 48K upgrade and link settings | 36–40 |
| 8 | Parts list for Issue 2 and Issue 3 boards, with an Issue 2 modifications column | 41–46 |
| 9 | Supplement No. 1: DC-DC converter modification, Issue 3B to 6A boards, servicing addenda, warranty seal, parts lists for Issues 4A, 4B, 5 and 6A | 48–56 |
| 10 | Supplement No. 2: Spectrum to Spectrum+ conversion, Spectrum+ keyboard assembly and operation, top and lower membrane diagrams | 57–60 |
What it contains
[edit | edit source]- Capacitor, resistor, diode, transistor and IC lists by board issue: section 8 for Issues 2 and 3, section 9.13–9.21 for Issues 4A to 6A. The values change between issues: C1–C8 are 47 nF on Issues 2 and 3 and 22 nF from Issue 4A, and C44 and C45 are not fitted on Issue 5.
- The internal voltage check (section 3.1.2) and the basic checks table (section 5.3.1), with the regulator input and output test points and the ULA, Z80 and ROM supply pins.
- The external power pack specification (section 5.2): a trough of at least 7.0 V at 1.4 A with 215 V AC mains, and a peak below 14 V at 600 mA with 265 V AC.
- The memory check and the table relating a wrong PEEK result to a RAM chip (section 5.4).
- The symptom lists in section 6, and the board-issue and ULA modification history in section 4.
- The Spectrum+ keyboard assembly instructions (section 10.3).
What it does not contain
[edit | edit source]The re-typeset edition does not include the T.I.S. Service Data and Repair Data that were bound into the 1984 edition; those are in the Thorn EMI edition. Supplement No. 1 refers to circuit diagrams and board layouts for Issues 4B, 5 and 6A ("shown here"), but the PDF does not include them. The editor marks the DC-DC converter instructions in section 9.2 as incorrect and says they should not be followed; the parts list in section 9.13 records what each board carries.
The editor has also corrected some values from the original, with notes, for example the IC14 pin 17 DC level in section 7.1. At least one transcription error remains: the Issue 2 modification value for C74 in section 8.5 is printed "47uf", where the 1984 edition prints 4.7 µF.
The manual does not cover the Sinclair ZX Spectrum 128, which has its own service manual.
Related period drawings
[edit | edit source]The Ferranti Archives 2026 holds circuit diagrams of the same boards from 1982 to 1984 that can be read with this manual:
- Sinclair's Issue Two circuit diagram, SRC 102, 16 August 1982, with the full edge-connector table and the optional 32K RAM section.
- An unnumbered 1982 Sinclair print, with the 5C102 patch, the 5C112 transistor modification and the clock modification of section 4 pencilled in as mods 1 to 3. The manual gives the transistor as TR6, a ZTX313; the print draws a ZTX312.
- Timex's Issue 3 drawing, June 1983, drawn for the 5C112E ULA family.
- Timex's Issue 6A drawing, "Ferranti version", 25 September 1984. Supplement No. 1 refers to an Issue 6A diagram that the re-typeset PDF does not include; Sinclair's own Issue 6A diagram is hosted separately (above).
- Sinclair's telex of 26 May 1983 amending Engineering Instruction/Spectrum 309, which gives the same R47, R49, R56 and R63 values as the table in section 4.1.2, except that it prints the 5C112 value of R47 as "2020R" where the manual has 220R.
Pages that cite this document
[edit | edit source]- Sinclair ZX Spectrum
- Sinclair ZX Spectrum General Maintenance
- Sinclair ZX Spectrum Troubleshooting Guide
- Sinclair ZX Spectrum Capacitor Replacement Guide: sections 8.5 and 9.13
- Sinclair ZX Spectrum Keyboard Membrane Repair: sections 1.8, 2, 5.5, 6.7 and 10
- Sinclair ZX Spectrum+, Sinclair ZX Spectrum+ General Maintenance, Sinclair ZX Spectrum+ Troubleshooting Guide and Sinclair ZX Spectrum+ Capacitor Replacement Guide
- Sinclair ZX Spectrum 128 General Maintenance and Sinclair ZX Spectrum 128 Troubleshooting Guide: the 48K procedures that carry over
Download: Sinclair ZX Spectrum Service Manual.pdf
Related pages
[edit | edit source]- ZX Spectrum Servicing Manual (Thorn EMI Datatech, 1984), the original 1984 edition with the T.I.S. sections
- Sinclair ZX Spectrum 128 Service Manual