What the Amiga's start-up screen colours mean
When you switch it on, the Amiga tests its own hardware and shows the result as a colour. Knowing how to read those colours helps you work out where the problem is before you open the case.
Difficulty: EasyTime: 15 min
Tools
- None: just a monitor or TV connected to the Amiga
The normal sequence
On a trouble-free start-up with Kickstart 1.x, the screen quickly changes from dark grey to light grey and then to white (2.x and 3.x use other shades), and the screen asking for a floppy disk (Kickstart 1.x) or the insert-disk animation (2.x and 3.x) appears. If there is a hard disk or a bootable floppy, it goes straight into Workbench or the game.
The error colours
If start-up stops on a colour, the colour tells you which test failed. These are the readings most widely used by the community, but not all of them apply to every Kickstart version; they confirm the area of the problem, not the exact part.
- 10Red: a ROM checksum error, but only from Kickstart 2.04 on. 1.x ROMs do not verify their checksum (according to Cloanto), so on 1.x red does not point to the ROM.
- 20Green: a problem with the Chip RAM, with Agnus, which controls it, or with CIA-A, which moves the ROM out of the way at start-up.
- 30Blue: a problem with one of the custom chips (Agnus, Denise, Paula), according to community lists. Note: we have not found this test in any Kickstart we could check. The 1.2 code doesn't have it, analyses of the 3.1 source say it is switched off there, and 1.3 is unconfirmed.
- 40Yellow: the processor took an exception (a bus error, for example) before the system had its error handlers in place, that is, before it could show a Guru. The processor is not necessarily faulty: it is often a bad ROM read, the bus, an expansion or a badly seated chip.
- 50Black screen and no picture: it could be the power supply, the processor, the ROM, the CIA chips or the video cable itself. This is the case that most needs measurements.
First steps at home
Remove all expansions (trapdoor, side, accelerators) and test again: many error colours come from expansions. If you have the experience, carefully reseating the socketed chips, with the machine switched off, sorts out oxidised contacts.
When to bring it to us
If the colour stays the same with no expansions, the problem is on the main board. Tell us the colour and the model in your repair request: it is a valuable clue for the diagnosis.
Request a repairThese guides are for information. Working on old electronics carries risks: do it at your own risk, with the machine unplugged, and never open power supplies or CRT monitors. If in doubt, bring the machine to us.