Amiga 1200 no boot – black screen

Amiga 1200 on the bench with black screen, no power led blink and no disk drive ticking.

DiagROM via serial output works, but no left mouse button.

Let’s see..

First thought was U7 (CIA) because left mouse button and no FDD ticking sound.

Removed U7, placed a PLCC socket and added a new CIA (8520) in place.

DiagROM and ATK (Amiga Test Kit) are working again. FDD ticking sound is back, mouse is working.

So.. U7 (CIA) was broken.