Sinclair QL Service Manual Prepared by THORN (EMI) DATATECH LTD for SINCLAIR RESEARCH LTD OCTOBER 1985 © Sinclair Research Ltd.
SECTION 1 SYSTEM DESCRIPTION LIST OF CONTENTS 1. 2. 3. 4. 5. 6. 7. 8. 9. Introduction Architecture MC68008 CPU Intel 8049 Intelligent Peripheral Controller (IPC) Memory Organisation Peripheral Control (ZX8301, ZX8302 and IC28) Microdrive Power Supplies Test RS232 Link Keyboard Matrix Interconnections QL Block Diagram QL Circuit Diagram (Issue 5) QL Circuit Diagram (Issue 6) 1. INTRODUCTION 1.
3.4 Control Bus. The control bus is a collection of individual signals which supervise the flow of data on the address and data busses. The block diagram shows most of these signals but reference to the circuit diagram shows other control signals available at the expansion port. Control lines are summarised below. 3.5 Interrupt Control (IPL0/2, IPL1). These inputs indicate the encoded priority level of the device requesting an interrupt, and are fed by IC24 (pins 23, 24) and IC23 (pin 26).
HIGH HIGH HIGH Interrupt Acknowledge 3.17 System Control inputs are used to either reset or halt the processor and to indicate to the processor that bus errors have occurred. There are three system control signals: BERR, HALT and RESET. 3.18 BERR (Bus Error). Not used on the QL. 3.19 RESET and HALT. The bidirectional RESET signal line acts to reset (start a system initialisation sequence) the processor in response to an external RESET signal.
FIGURE 1.1 RS232 LINK 4.10 On receipt of a start bit, IC24 is interrupted, and a subroutine clocks in the data bits, synchronised by the baud rate generator. The data, up to about 20 bytes per RS232 channel, is tnen buffered in IC24. At the same time, IC24 receives commands (and sends reports) via the serial link with IC18 which i-s controlled by IC23. When IC24 receives a command from IC18 to empty one of its buffers, it does so, down the serial link via IC23. 4.
the loudspeaker. The loudspeaker is damped by resistor R104 (post-Issue 6 only). 5. MEMORY ORGANISATION 5.1 Introduction 5.1.1 The pre-Issue 6 version was supplied in both EPROM and ROM forms with on-board straps enabling the selection of ROM. Both versions have 48k of ROM and in both versions there are 128k bytes of RAM memory. Figure 1.3 shows how the memory is organised. 5.1.
6.1.3 The net result is the five video signals output from IC22 on pins 32, 31, 30, 12 and 11. 6.1.4 The RGB signals are fed to level-setting resistor divider network R48-R53 and a.c. coupled to RGB-to-PAL converter IC28 on pins 3, 4 and 5. The composite sync signal CSYNC is input on pin 2. External components of the circuit provide a number of clamp circuits; the luminance and chrominance signals are fed out, filtered and fed back in; the chrominance 4.
being written. The erase head is displaced from the write head and is timed by IC23 to sink current before the write head is enabled. 7.2 Microdrive Selection 7.2.1 Microdrives are selected using the MDSELDH and MDSELCKN signals from IC23. Each microdrive control chip, IC29 and IC30, contain one stage of a shift register, realised by a flip-flop. MDSELCKN is connected to each microdrive and MDSELDH is routed to pin 22 (COMMS IN) of IC29, which is the input to the shift register.
the processor data bus. If this functions correctly it is close to a guarantee that the whole system is functional. 9.2 A test tape is available which exercises most of the functions of the QL and is a useful initial diagnostic tool. See Section 3 for details. FIGURE 1.3 QL BLOCK DIAGRAM FIGURE 1.4 QL CIRCUIT DIAGRAM (Issue 5) FIGURE 1.
SECTION 2 DISASSEMBLY/ASSEMBLY 1. Disassembly Access to Internal Components Microdrive Circuit Board Loudspeaker Microdrive: Disassembly for Repair Keyboard: Disassembly for Repair 2. Assembly Loudspeaker Circuit Board Microdrives Keyboard Case Assembly 1. DISASSEMBLY 1.1 Access to Internal Components 1.1.1 Unplug all input/output leads and turn the QL upside down to reveal eight self-tapping screws, 4 x 5/16-in along the front edge, below the overhang, and 4 x 1.1/4-in along the rear edge.
1.6.2 Release six 1/4-in pan head screws securing the keyboard backing plate to the upper case. This allows the plate, with membrane attached, to be lifted clear revealing the keyboard bubble mat below. The membrane is separated from the plate by carefully breaking the adhesive seal holding the ribbon cables in position; the bubble mat is simply lifted from its position revealing a set of keys below. 1.6.
SECTION 3 SYSTEM TEST 1. Introduction 2. System Test 3. Procedure 1. Power-Up 2. Colour Test 3. Sound Test 4. Network Test 5. RS232C Loopback Test 6. Keyboard Test 7. Joystick Test 8. Real-Time Clock Test 9. Microdrive 2 Test 10. Microdrive 1 Test 11. Microdrive Tape Not Inserted Correctly 12. End of Test 1. INTRODUCTION 1.
3.1.4 Insert a blank tape cartridge into MDV2 as requested. 3.2 Colour Test 3.2.1 After the message to load a blank cartridge into MDV2 is displayed, both screens should clear and then display the following colour test card. NOTE: On each colour bar the word 'Test' should be written 8 times, once in each of the following colours from top to bottom Black - Blue - Red - Magenta - Green - Cyan - Yellow - White 3.2.
3.6 Keyboard Test 3.6.1 Check that the following is displayed: 3.6.2 Press the key indicated by a dark blue background on the display. The blue background should be replaced by green and move onto the next key. Press all keys in sequence and note that on pressing the ALT key the message: 'keyboard test complete' is displayed momentarily. NOTE: Each key should be pressed individually, NOT skimmed over. If keys have a tendency to stick, the cause should be investigated. 3.7 Joystick Test 3.7.
3.9.1 Check that the following message is displayed and that MDV2 starts to run and the corresponding red LED is illuminated. 3.9.2 Insert a blank cartridge in MDV1. 3.9.3 After a short delay the following message should be displayed: NOTE: On pressing the space bar two bleeps should be heard and the following message displayed in green: Microdrive 2 test OK 3.10 Microdrive 1 Test 3.10.1 As microdrive 2 test (para 3.9). 3.11 Microdrive Test Not Inserted Correctly 3.11.
3.12 End of Test 3.12.1 On satisfactory completion of Microdrive 1 Test the following message should be displayed on green: QL TEST COMPLETE 3.12.2 Press the RESET pushbutton and check that the display is as shown in para 3.1.1.
SECTION 4 FAULT DIAGNOSIS AND REPAIR 1. Introduction 1. Test Equipment 2. Modification History 3. Mandatory Modifications 2. Fault Diagnosis 1. Techniques 2. Power Up 3. Keyboard 4. Microdrive 5. Video 6. Fault-Finding Guide 3. Repair 4. Firmware Upgrade 1. INTRODUCTION 1.1 Test Equipment 1.1.1 Section 4 is intended as a guide to fault diagnosis and repair.
Build Standard IC D6 D7 D8 D9 D10 D11-D14 IC33 IC34 IC33 IC34 IC33 IC34 IC33 IC34 IC33 IC34 IC33 IC34 ROM EPROM 32k 32k 16k 32k 16k Software Standard Remarks AH 16k of EPROM mounted pickaback on IC33 JM 16k of EPROM mounted pickaback on IC33 32k 16k 32k 16k 15k 32k 16k - AH AH JM JM 1.2.2 A newly laid out p.c. board was introduced at Issue 6 to reflect the removal of IC17 and IC27 and the addition of HAL IC38.
F1...MONITOR F2...TELEVISION © 1983 Sinclair Research Ltd 2.2.2 This indicates that most of the system is working. If the QL does not power up, and display the expected copyright screen, switch off and repeat the power-up operation two or three times. It is possible for the QL to lock-up on start-up and appear lifeless. 2.2.3 Lack of a copyright screen indicates a fundamental failure. First check voltages as set out in the table below.
2.2.
300 DEFine PROCedure stop_all 310 sedes 8,0 320 END DEFine Key-in start_mdv(n) to turn on drive number n and to keep it spinning continuously. Key-in stop_all to stop all drives spinning. 1. 2. 3. 4. 5. 6. Start microdrive 1. Using an oscilloscope, check that a signal is present from the read head (INA, IC29) and trace it through to the RAW inputs on the 8302. If there is nothing coming from the head, then the head is faulty.
Erase function not working. MDV1(2) does not run 1. 2. Check TR3, D28. Renew IC23. Check TR7(TR6), TR5(TR4) 2.5 Video 2.5.1 Video faults are either total, when there is absence of monitor and TV signal, or may be categorised as either monitor or TV faults. 2.5.2 If a TV is initially connected and is giving no picture it might be worth tuning the set slighly either side of the expected tuning point. (It is possible the modulator has drifted slightly).
Keyboard locks-up after prolonged use. RS232-C/Printer Fails RS232 loopback test. Network Fails network test. Renew IC24 Renew IC18 Check J5, J6 Renew IC25, IC26 Renew IC23 Renew IC24 Check J9, J10 Check TR2 and associated components. Fails sound test: Sound No sound Real-time clock Joystick Fails real-time clock test Fails joystick test. Fails reset test Does not reset. General System locks up after prolonged use. Computer 'crashes' at random intervals or after prolonged use.
10. Return EPROMs to Sinclair Research Ltd. FIGURE 4.2 KEYBOARD FORMAT FIGURE 4.
APPENDIX A TO SECTION 4 KNOWN BUGS AND THEIR REMEDIES 1. 2. 3. 4. 5. 6. Monitor Connections Known Bugs Printing Problems SER Outputs How to Cure a Crashing QL Flickering Displays 1. MONITOR CONNECTIONS 1.1 You may have been experiencing difficulty in getting an adequate performance from a monitor connected to your QL. Given below is a revised set of wiring instructions for the connection lead. These instructions replace those given in page 31 in the Concepts section of the QL User Guide. 1.
3. The command "CURSOR #n, a, b, c, d" is not accepted. Clue: "CURSOR #n, a, b, c, d" gives "bad parameter" (NB: message "channel not open" is NOT a bug). 4. If an expression in a DATA statement starts with a bracket [(], the rest of the DATA line is ignored. Clue: DATA ...., ( ...), 5. GOSUB in short FOR loops can act as ENDFOR. Clue: GOSUB in a short FOR loop. 6. If you ask for DIR mdv8_, then DIR mdv2_ will not work properly thereafter.
buffer full of data is printed. 3.3 If the problem does occur, look at the wiring of the RS-232 lead on the end that connects to the printer, and check that a lead exists, connected from pin 4 to pin 20. 4. SER OUTPUTS 4.1 There is one potential fault with the SER outputs from the QL that is not obvious to find. 4.2 If either pin 1 (ground) or pin 6 (+12V) is not properly connected (e.g.
APPENDIX B TO SECTION 4 USER HINTS The following points may be of help in spotting 'non-faults' on QLs. 1. Please note that if you want the QL to tell you which version of ROM it has, you should enter 'PRINT VER$' and not 'PRINT VERS'. 2. If you try to run Abacus, Archive, Easel or Quill on microdrive 2 instead of microdrive 1, you get an error message, typically 'AT END 200 NOT FOUND'. 3. When saving data on microdrive 2 while using Abacus, etc.
APPENDIX C TO SECTION 4 MANDATORY MODIFICATIONS 1. Fitment Checks 2. Improvement to Microdrive Performance 1. FITMENT CHECKS 1.1 Refer to the mandatory modifications described on page 4.3 and page 5.1 in this manual. To check that if these modifications have been made, look for R102 and R103 through the SER1 port. If these resistors are in place you can assume that the other modifications have been carried out. With build state D12 or higher the modifications have already been incorporated. 2.
FIGURE C3 ISSUE 6 BOARD - SOLDER SIDE (SRL/EI/1119-1)
APPENDIX D TO SECTION 4 MICRODRIVE FAULT FINDING 1. Introduction 2. Mechanical Checks 3. Using the Signal Test Program Write Check Read Check Erase Check 4. Faults on Early Microdrives 1. INTRODUCTION 1.1 This guide is intended to give a base of understanding for the most frequent faults occurring on QL microdrives. It contains descriptions of faults and tests to help in finding them. 1.2 The microdrive is a slave mechanism for transferring data to and from magnetic tape.
3.3.1 After writing to tape, carry out the following while in read mode. 1. Check data lines ULA pins 19 (24) and compare to fig D3. If the waveform is very unstable in X axis, a mechanical fault is probable. If the waveform is poor or is not present at all check the pk-pk signal at pins 4 and 5 (14 and 15). See fig D4. 2. If the signal is present and correct there is a fault in the intermediate read stages. See circuit and fig D5.
0 PAUSE 50 350 SAVE ser1 360 END DEFine TABLE D1 - SIGNAL TEST PROGRAM FIGURE D2 FIGURE D1 MICRODRIVE SIGNAL (100 KHZ WRITE) FIGURE D3 FIGURE D6 FIGURE D5 FIGURE D4 MICRODRIVE SIGNALS (100 KHZ READ) FIGURE D7 MICRODRIVE SIGNALS (FORMAT READ) FIGURE D8
FIGURE D9 ULA 2G007 - INTERNAL CIRCUIT
SECTION 5
PARTS LISTS 1. 2. 3. 4. Serial Numbers Parts List/Modification History Retrospective (Mandatory) Modifications Notes to Tables 1. SERIAL NUMBERS 1.1 The serial number is visible on a label attached to the underside of the Sinclair QL thus: D13 59643. Prefix D13 relates to the build standard (B/S) and Issue Number, 59643, is the number of the production run.
2. PARTS LISTS / MODIFICATION HISTORY 2.1 Parts lists for the Sinclair QL are presented in tabular form. They cover p.c. board Issue 5 (build standard D6 to D13) and p.c. board Issue 6 (build standard 14 and beyond). The Issue 6 p.c. board introduces a number of relatively minor circuit changes from Issue 5. These are illustrated in Figures 5.1 and 5.2 and itemised in Tables 5.1 to 5.5 under separate columns labelled Issue 5 and Issue 6. 2.
Keyboard and Bubble Mat Keyboard Assembly Fixings Adhesive Cable Clip Double-sided Tape (0.5-in wide) 1/4-in self-tap - keyboard backplate ROM Cartridge Bung MDV Extension Bung BUS Extension Bung General Assembly Fixings 5/16-in self-tap (4 off) Keyboard/Base 1 1/4-in self-tap (4 off) TABLE 5.2 HEATSINK ASSEMBLY Description Manufacturer/Type Heatsink Wakefield Mk.
R40 R41 4K7 R42 R43 4K7 R44 R45 4K7 R100 R101 2K2 DIODES D12 D13 1N4148 D14 D15 1N4148 D22 D23 1N4148 INTEGRATED CIRCUITS IC29 IC30 2G007-Issue 3 IC31 IC32 78M05 MISCELLANEOUS HBC1 HBC2 A10021 As Issue 5 5%, 1/4W 5%, 1/4W 5%, 1/4W 5%, 1/4W As Issue 5 (2) ULA Ferranti +5V Regulator As Issue 5 As Issue 5 2-off each 7-way flex. connector/cable TABLE 5.
R8 R9 R10 R11 R12 R13 R14 R15 R16 R17-24 R25 R26 R27 R28 R29 R32 R33 R46 R47 R48 R49 R50 R51 R52 R53 R54 R55 R56 R57 R58 R59 R61 R62-69 R70 R71 R72-79 R80 R35 R86 R87 R88 R89 R90 R91 R92 R93 R94 R95 R96 R97 R98 R99 R102 R103 R104 47K 3K3 680R 1K 3K9 10K 47R 330R 330R 10K 180R 3K3 3K3 1K 1K 820R 820R 1K 2K2 8K2 8K2 8K2 1K 1K 1K 47K 2K2 6K8 11K 55K6 22K 15R 3K3 1M 2K2 33R 15M 100R 270R 1K 75R 1K 1K 47K 390R 3K3 3K3 1K 2K2 1K 4K7 2K2 33K 33K 82R As Issue 5 (1) (2) ZERO Ω ZERO Ω 82R (2) (2) (2) 5%, 1/4W
R105 1K R106 1K JU1-6 ZERO Ω DIODES D1-D17 1N4148 D20 LD235R D21 LD235R D25 BA157 D26 BA157 D27 LD235Y D28 1N4148 D29 1N4148 TRANSISTORS TR1 BC184 TR2 ZTX510/BSX29-SGS TR3 BC184 TR4 BC184 TR5 RC184 TR6 ZTX551 TR7 ZTX551 TR8 ZTX313/MPS2369 TR9 ZTX313/HPS2369 INTEGRATED CIRCUITS HM4864P-2 TMS4164-15NL MCM6665AP15 MK4564N15 IC1-16 UPD4164C-3 MSM3764-15RS TMS4146-12NL HYB4164P2BD IC17 74LS00 IC18 MC68008 IC19, IC20 74LS257 IC21 74LS245 IC22 ZX8301 IC23 ZX8302 IC24 8049 IC25 1488 IC26 1489A IC27 74LS03 IC28 MC13
J11 TE9FS/18B J12 TE11FS/18B HBC1/2 LS MWP2P-1B LEDS (D20, D21, D27) MWP6P-1B MISCELLANEOUS COMPONENTS TC1 540pF M1 UM1233 X1 HC18-U X2 MX38 X3 HC18T-U X4 S3 RESET 4 off As Issue 5 P/B Switch 9-way flex 11-way flex Aries, 7-way flex. socket Burndy Burndy Trimmer Astex, E36 Modulator 15MHz, 20ppm 32.768kHz, 20ppm 4.4336MHz, 20ppm 11MHz, 10ppm Schadow, DPCO FIGURE 5.1 PRINTED CIRCUIT BOARD (Issue 5) COMPONENT LAYOUT FIGURE 5.
Table of Contents Sinclair QL Service Manual List of Contents List of Illustrations History Sheet SECTION 1 SYSTEM DESCRIPTION LIST OF CONTENTS 1. INTRODUCTION 2. ARCHITECTURE 3. MC68008 CPU 4. INTEL 8049 INTELLIGENT PERIPHERAL CONTROLLER (IPC) 5. MEMORY ORGANISATION 5.1 Introduction 5.2 Read/Write Operations 6. PERIPHERAL CONTROL (ZX8301, ZX8302, IC38 and IC28) 6.1 ZX8301, IC22. 6.2 ZX8302, IC23. 7. MICRODRIVE 7.1 Introduction 7.2 Microdrive Selection 7.3 Read/Write Operations 8. POWER SUPPLIES 9.
4. SER OUTPUTS 5. HOW TO CURE A CRASHING QL 6. FLICKERING DISPLAYS APPENDIX B TO SECTION 4 USER HINTS APPENDIX C TO SECTION 4 MANDATORY MODIFICATIONS 1. FITMENT CHECKS 2. IMPROVEMENT TO MICRODRIVE PERFORMANCE 3. COLLAR FOR QL MICRODRIVE 2 APPENDIX D TO SECTION 4 MICRODRIVE FAULT FINDING 1. INTRODUCTION 2. MECHANICAL CHECKS 3. USING THE SIGNAL TEST PROGRAM 3.2 Write Check 3.3 Read Check 3.4 Erase Check 4. FAULTS ON EARLY MICRODRIVES SECTION 5 PARTS LISTS 1. SERIAL NUMBERS 2.
