| Click here to select a new forum. |
| PM8500 - av video out |
Posted by: lobust on 2026-04-19 07:25:34
My recently acquired 8500 thinks it has a television connected and it's a bit of a nuisance.
- Is it normal for the av video out to be active with nothing plugged in?
- If yes, how do I disable it?
- If no, ideas how to fix it?
|
Posted by: bigD on 2026-04-19 12:00:02
IIRC, the AV port is controlled by the Monitors control panel. Is the display shown there? |
Posted by: lobust on 2026-04-19 14:59:36
IIRC, the AV port is controlled by the Monitors control panel. Is the display shown there? Yes, it shows as a second monitor like any other. |
Posted by: joevt on 2026-04-19 15:47:34
The 8500/8600 can sense when a composite or s-video display is connected.
The DingusPPC emulator does emulate this behaviour.
The bits are in a board register accessed at address F301E000. It's a 16-bit little-endian register.
Read the register in Open Firmware like this:
F301E000 rw@ 4 u.r
Composite video is 0x0080 for not connected. 0 for connected.
S-Video is 0x0040 for not connected. 0 for connected.
Unused bits are pulled high: FF3F.
We should be able to see which is stuck at connected.
I don't know if there's any Power Mac 8500/7500/7600/8600 schematics that can help you find the related components on the motherboard. |
| 1 |