The IC24 is a 74LS00N Logic IC and can be replaced with a modern 74HCT00 Logic IC
A modern replacement can be found here:
| Shop | Link |
|---|---|
| RetroRevivalShop | http://retrorevivalshop.co.uk/index.php?main_page=product_info&cPath=5&products_id=30 |
| Retroleum | https://www.retroleum.co.uk/zx-spectrum-chips |
Using a multimeter check the traces for IC24, the the diagram below for chip pin position
| Pin | Traces to | Voltage | Description |
|---|---|---|---|
| 1 | IC23 Pin 14 / IC2 Pin 11 | ||
| 2 | IC23 Pin 14 | ||
| 3 | |||
| 4 | IC1 Pin 3 | ||
| 5 | IC23 Pin 11 | ||
| 6 | IC24 Pin 9 | ||
| 7 | IC23 Pin 7 | Ground | |
| 8 | IC23 Pin 10 | ||
| 9 | IC24 Pin 6 | ||
| 10 | IC1 Pin 37 | ||
| 11 | |||
| 12 | IC24 Pin 2 | ||
| 13 | IC23 Pin 14 | ||
| 14 | IC23 Pin 14 | Vcc |
END