Amiga 4000 takes eight minutes to boot (solved) sort of

[Castellen]

While the computer is in the state where nothing is happening for 8 minutes, repeatedly press the caps lock key at least 10 times or more.  If the LED eventually sticks on or off, then it could be something holding the computer in reset state.  I've seen real time clock corrosion damage cause a similar issue before as well, so if there's been previous corrosion damage, remove both U177 and U178 to see if that resolves the delayed booting problem; the computer will boot normally without those ICs, though you'll have no RTC.  Remove U891 if there's signs of corrosion around that; the computer will boot without it, though you'll have no fast memory.

If the caps lock LED reliably turns on and off each time, then the CPU is at least active and suggests that the system is probably waiting for something in software (e.g. scsi.device) as others have alluded to.

Failing that, I can repair your A4000 main board if needed.

http://amiga.serveftp.net

[Castellen]

No, unlikely to be U177, U891, etc, in that case.  Sounds as though the system is waiting an unusually long time for something if there's valid CPU activity.

If you reduce the system to bare basic, e.g. A3630/A3640 CPU board (with J100/J104 set correctly) and nothing connected except the power supply and monitor; do you get the 'insert disk' screen after about 30 seconds, or does it take 8 minutes?

If the 'insert disk' screen appears after the typical 30 seconds or so, then probably there's an issue with drives as others have already mentioned; you should be able to narrow things down from there.

If the 'insert disk' screen takes 8 minutes to appear with no floppy or hard drives connected, then there's likely some other problem with the main board at a hardware level.  It gets fairly difficult to diagnose yourself from that point.  I use special run-time monitoring equipment for quickly diagnosing that sort of problem to see what's happening with the ROM software, so you can contact me separately if it's looking to be a main board hardware issue that you need repaired.