Got myself a broken ZX the other day and it arrived with a spare motherboard. The spare is a later revision so I started with that one.
This is my first Spectrum repair so was a little unsure where to start.
This started up with garbage on the screen in the form of many vertical lines.
As the Z80 was socketed I tested that. Failed and replaced.
Looking around the board I saw a transistor that was a little damaged. Removed TR4 and it was shorted internally. It is a ZTX650. I robbed one off the other board and fitted it.
The Spectrum now works but the picture is really really bad quality.
The keyboard also doesn’t function properly, half of the keys don’t work. Ive read the keyboard membranes are usually shot so ill have to order one up.