Amiga 4000 doesn't work with Toaster 4000 connected

[RobertB]

But if I have either A520 OR the Toaster fitted, machine boots normally!

Is it normal for the Toaster to somehow conflict with the A520, or something connected to the RGB port? It makes no sense for me.

From the Video Toaster System 2.0 Manual, Video Toaster Appendices, Appendix 2, p.7, "Installing the Video Toaster Card" --

Installing the Video Toaster Card

Basic System Requirements
The following list describes the basic computer configuration required to run the Video Toaster. This is considered the absolute minimum. If you have purchased a Video Toaster Workstation, you need not concern yourself with this chapter.

* An Amiga with the "Fat Agnus" chip installed. This is the 1 megabyte Agnus chip. The newer 2 megabyte Agnus chip also will work with the Video Toaster.

...

* Four megabytes of fast RAM, sometimes called expansion RAM.

* Hard drive with 40 megabytes of free space (The Toaster software requires 40 megabytes for the installation procedure, but only 30 once the installation is completed.)

* Hard drive controller card that is auto-mounting and auto-booting. Systems sold today all follow these conventions. If you have purchased an older, used computer, you may need to have a dealer check this for you.

* One RGB or RGB/Composite monitor.

Note: if there is no RGB monitor attached to the Amiga's RGB port, then the Video Toaster's encoder will not function properly. If you choose not to use an RGB monitor, you will need to install an RGB terminator plug on the RGB output.

* One additional composite video monitor.

The above system meets the Toaster's basic requirements. NewTek highly recommend using one RGB monitor and 2 TV monitors, or 3 TV monitors, for ease of use. The "best" configuration for the Video Toaster is the one that will suit your particular needs.

     So, the A520 is not considered to be an RGB monitor, and thus the Video Toaster won't function properly.

          On the road,
          Robert Bernardo
          Fresno Commodore User Group - http://www.dickestel.com/fcug.htm
          Southern California Commodore & Amiga Network - http://www.portcommodore.com/sccan

P.S. I had a similar problem with the A520.  When it was connected, an A2000, with 80386 Bridgeboard and DOS 5.0 and an A-Max module with Mac OS 6.0, refused to boot up or froze the Workbench screen when it did boot.  When the A520 was removed, the A2000 booted normally.