The IC23 is a 74LS32 Logic IC and can be replaced with a modern 74HCT32 Logic IC
A modern replacement can be found here:
| Shop | Link |
|---|---|
| RetroRevivalShop | https://retrorevivalshop.co.uk/index.php?main_page=product_info&products_id=35 |
| Retroleum | https://www.retroleum.co.uk/zx-spectrum-chips |
Using a multimeter check the traces for IC23, the the diagram below for chip pin position
| Pin | Traces to | Voltage |
|---|---|---|
| 1 | IC2 Pin 19 | |
| 2 | IC1 Pin 38 | |
| 3 | Upper Ram (IC15-22) Pin 4 | |
| 4 | Upper Ram (IC15-22) Pin 4 | |
| 5 | C64 & R70 Left | |
| 6 | Upper Ram (IC15-22) Pin 15 | |
| 7 | Upper Ram (IC15-22) Pin 16 | |
| 8 | R70 Right | |
| 9 | C63 & R71 Left | |
| 10 | IC24 Pin 8 | |
| 11 | IC24 Pin 5 | |
| 12 | IC2 Pin 22 | |
| 13 | IC2 Pin 22 | |
| 14 | IC2 Pin 11 |
END