A2000 ATX PSU Power Adapter Cable [ADAPSU010] > what about -5V ?

[RetroNinja]

For AmigaKit's power supply cable:

A2000 ATX PSU Power Adapter Cable for Amiga 2000
[ADAPSU010]

Does anyone know if the ATX power supply has to have a -5V line? Or, does this cable convert a spare +5V to -5V? Another way to say the same thing, is there any intelligence in this adapter or is it just a straight through cable converter?

[Castellen]

From the photos online it's a passive cable that appears to connect -5V from the ATX supply to -5V on the A2000 connector (white wire).

https://www.amigastore.com/a2000-power-adapter-cable-amiga-2000-p-998.html

It's fairly rare to see much that uses -5V.  All I can think of is a few older Zorro 2 expansion cards and video processing expansions.  The A2000 itself will operate fine without the -5V supply.

[RetroNinja]

Huh, I was under the impression the A2000 needed for the -5V for the boot process. Thanks for the info.

[Castellen]

I was under the impression the A2000 needed for the -5V for the boot process.

The A2000, as with other Amigas, only needs +5V to boot normally.  If you want audio output and RS232 serial, then you need both +12V and -12V as well.  Most floppy drives and mechanical hard drives need both +5V and +12V.

The A2000 also needs the 50Hz/60Hz tick signal that normally comes from the power supply.  It won't boot without it as this timing reference increments some of the hardware timers.  For non-original power supplies that don't provide the 'tick' signal, you can change main board jumper J300 from external to internal which drives the timer from an internally derived signal instead.