New Build ZX Spectrum - Installing The Transistors
The transistors have some of the biggest differences with the original board so far. Whether it is because the original transistors are no longer available to buy and equivalents are required, or just that people have found using different specifications has resulted in improved picture quality.
The main differences are at TR1, TR2 and TR3. Other positions have mostly replaced with equivalent available parts from discontinued lines.
If you are following our location guide, and if not you really should, we have put in all the new build transistors here, so just follow that. There are a couple of things to watch out for though.
With TR1 and TR2 as we are using BC549 these should be installed in the opposite direction the PCB shows. So for TR1 the flat edge of the transistor should be facing up, and for TR2 the flat side should be facing down.
| Position | Value | Notes |
|---|---|---|
| TR1 | BC549 | Flat side north |
| TR2 | BC549 | Flat side south |
| TR3 | 2N4401 | |
| TR4 | ZTX651 | |
| TR5 | ZTX753 | |
| TR6 | BC337 | Flat side east |
| TR7 | BC549 | Flat side north |
| TR8 | BC549 | |
| TR9 | BC549 |