Editing Sinclair QL Service Manual

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The '''Sinclair QL Service Manual''' is Sinclair Research's official service documentation for the [[Sinclair QL]]. It was '''prepared by Thorn (EMI) Datatech Ltd for Sinclair Research Ltd''', and the copy hosted here is '''Manual Issue 3, October 1985''' — the revision that added Appendices A to D.<ref name="ql">Sinclair Research Ltd, ''QL Service Manual'', prepared by Thorn (EMI) Datatech Ltd, Manual Issue 3, October 1985, © Sinclair Research Ltd. Hosted on this wiki as [[:File:Sinclair QL Service Manual.pdf]]. 74 pages. Source for the contents and illustration lists, the manual history sheet, the sub-section breakdown of Sections 1 to 5, the parts-list table numbering, and the location of the serial-number label.</ref>

Unusually for a machine of its era it is written at '''full component level''': as well as fault diagnosis it contains the complete parts lists, so every capacitor, resistor and semiconductor designator and value on the main board and the Microdrive boards is documented, for both the Issue 5 and Issue 6 boards.

It is the primary reference for [[Sinclair QL Maintenance Guide]], [[Sinclair QL Troubleshooting Guide]], [[Sinclair QL Capacitor Replacement Guide]] and [[Sinclair QL Microdrive Troubleshooting Guide]].

== Manual history ==

The history sheet records three issues of the manual itself, which is worth knowing because a copy that stops at Section 4 is an earlier printing rather than a damaged one:<ref name="ql" />

{| class="wikitable styled-table" style="width:75%; text-align:left;"
|+'''Manual issues'''
! Issue !! Date !! Change
|-
| 1 || January 1985 || First release
|-
| 2 || June 1985 || Minor changes to pages 1.5, 3.6, 4.1, 4.3, 4.4, 4.15, 4.17 and 5.7
|-
| '''3''' || '''October 1985''' || '''Appendices A, B, C and D added to Section 4'''
|}

== Contents ==

{| class="wikitable styled-table" style="width:100%; text-align:left;"
|+'''Section by section'''<ref name="ql" />
! Section !! Covers
|-
| '''1 — System description''' || Introduction; architecture; the MC68008 CPU; the Intel 8049 Intelligent Peripheral Controller; memory organisation; peripheral control (ZX8301, ZX8302 and IC28); the Microdrive; '''power supplies'''; test
|-
| '''2 — Disassembly / assembly''' || Access to internal components, Microdrive, circuit board, loudspeaker, Microdrive disassembly for repair, keyboard disassembly for repair, and the assembly sequence for each
|-
| '''3 — System test''' || The full post-repair test sequence: power-up, colour, sound, network, RS232C loopback, keyboard, joystick, real-time clock, Microdrive 2, Microdrive 1, and the tape-not-inserted-correctly case
|-
| '''4 — Fault diagnosis and repair''' || Test equipment; '''modification history'''; '''mandatory modifications'''; diagnosis techniques; power-up, keyboard, Microdrive and video fault trees; the fault-finding guide; repair; firmware upgrade
|-
| Appendix A || Known bugs and their remedies
|-
| Appendix B || User hints — including the monitor connection options
|-
| Appendix C || '''Mandatory modifications''', with board figures
|-
| Appendix D || Microdrive fault finding, with the signal waveforms
|-
| '''5 — Parts lists''' || Tables 5.1 to 5.5, with Issue 5 and Issue 6 columns throughout
|}

=== The parts-list tables ===

{| class="wikitable styled-table" style="width:80%; text-align:left;"
|+'''Section 5'''<ref name="ql" />
! Table !! Assembly
|-
| '''5.1''' || General assembly
|-
| '''5.2''' || Heatsink assembly
|-
| '''5.3''' || Microdrive chassis (two per machine)
|-
| '''5.4''' || Microdrive board — listed as '''MDV1 and MDV2 circuit references side by side''', with Issue 5 and Issue 6 columns
|-
| '''5.5''' || Final board assembly — the main PCB, over four pages
|}

Table 5.4's two-column layout is a small thing that saves real time: the same component appears under its MDV1 designator and its MDV2 designator on the same line, so you are never guessing which drive a reference belongs to.

Section 5 also documents where to read the machine's '''serial number''' — on a label on the underside of the case — and carries the modification history against it.<ref name="ql" />

== Illustrations ==

{| class="wikitable styled-table" style="width:85%; text-align:left;"
|+'''Figures'''<ref name="ql" />
! Fig. !! Subject
|-
| 1.1 || RS232 link
|-
| 1.2 || Keyboard matrix interconnections
|-
| 1.3 || QL block diagram
|-
| '''1.4''' || '''QL circuit diagram, Issue 5'''
|-
| '''1.5''' || '''QL circuit diagram, Issue 6'''
|-
| 4.1 || Motor location jig
|-
| 4.2 || Keyboard format
|-
| 4.3 || Head chassis
|-
| C1, C2 || Issue 5 board — component-side and solder-side modifications
|-
| C3 || Issue 6 board — solder-side modification
|-
| D1–D8 || Microdrive signals at 100 kHz: write, read and format read
|-
| '''D9''' || '''ULA 2G007 internal circuit'''
|-
| '''5.1''' || '''PCB component layout, Issue 5'''
|-
| '''5.2''' || '''PCB component layout, Issue 6'''
|}

Several of these are also hosted individually — see the circuit-diagram section of [[Sinclair QL]].

== Safety notices ==

The manual opens with its own safety statement: it contains WARNING and CAUTION notices that must be followed, and it states that all users of the equipment it describes should have received adequate training in its use.<ref name="ql" /> Sinclair's own mandatory modifications in Appendix C are not optional advice — they are changes Sinclair required its service agents to make.

<pdf> File:Sinclair QL Service Manual.pdf </pdf>

Download the Sinclair QL Service Manual here: [[:File:Sinclair QL Service Manual.pdf|Sinclair QL Service Manual.pdf]]

== Used by ==

* [[Sinclair QL Maintenance Guide]]
* [[Sinclair QL Troubleshooting Guide]]
* [[Sinclair QL Capacitor Replacement Guide]]
* [[Sinclair QL Microdrive Troubleshooting Guide]]

== Related pages ==

* [[Sinclair QL]]
* [[Sinclair ZX Spectrum Service Manual]]

== References ==

<references />

[[Category:Sinclair Computers]]
[[Category:Service Manuals]]