This page contains technical information across a wide variety of topics that hopefully people will find useful.
Boring legal disclaimer: No responsibility is taken for any loss or damage resulting from advice given in these articles.
General Information
- ZX Spectrum Models and some basic technical info on each
- ULA types – what’s compatible with what machine etc.
- Spectrum compatibility issues (i.e. why won’t my game run!)
- Memory contention and the floating bus explained
- List of Z80 instructions, opcodes, characters and timings
- Inside the Prototype ZX Spectrum’s ROM
Maintenance
- Recapping your Spectrum
- Capacitor Lists: 16/48K, 128K/+2/+2A/+3
- Servicing your +2/+2A Tape deck
- Replacing the drive belt on your +3 FDD
- Refelting ZX Microdrive Cartridges
- Spare parts for all Spectrums
Repair
Upgrades
- Fitting an EPROM to a 16/48K Spectrum
- Upgrading a 16K Spectrum to 48K
- Upgrading esxDOS on your DivMMC device
- Modifying a +2A Sound socket to accept tape input (+3 standard)
- Adding an external tape input socket to a Grey +2 (thanks to Duncan Edwards)
- Issue 1 DIY 32K expansion board
Audio Modifications
Video Modifications
- Composite Mod for the 48K range
- How to fix Issue 1/2 yellow or blue screen tint
- Fixing vertical ‘jailbars’ on your 48K, 128K and Grey Spectrum +2
- Making your 128/+2/+2A/+3 RGB socket SCART compliant
- Modifying a +2A or +3 to output Composite on the RGB port
- Removing Blue/Yellow Ghosting from the 128/+2’s Video Output
- Modifying an Investronica 128 For Proper Composite Output
Other Modifications
- Rewiring your +2/+3 Joystick ports to Atari standard
- Applying the Unrainer/IN 7FFD fix to 128/Grey +2 machines
- Constructing an alternative PSU for the +2A/+3 machines
- Performing the IN FF mod on a +2A/+3 (restores rudimentary floating bus behaviour)
- Fixing Keypad Issues on an Issue 6K 128K Toastrack
- Unlocking Your Recreated Spectrum Bluetooth Keyboard
Technical References and Documentation
- ZX Spectrum Service Manual (includes Supplement No.1 – Issue 3B to 6A, and Supplement No. 2 – Spectrum+ Description and Upgrade Procedure)
- ZX Interface 1, Interface 2 and Microdrive Service Manual
- ZX Printer Service Manual
- ZX Spectrum 128 Service Manual
- ZX Spectrum +2 Service Manual (Grey model with Z70500 PCB)
- Schematics and Layout files for various Spectrum models
Useful Links
Ben Versteeg’s guide to video fixes and cable pinouts for the 128/+2/+3 range. Contains information on how to construct your own SCART cables, correcting video related PCB errors on the Grey +2, detaching audio from the composite out on 128/Grey +2 etc.
Improving the audio quality on the +2A/+3, and +2B / +3B (by ZXGuesser)