You may encounter the following symptoms when using a Power Macintosh AV system with a monitor attached to the DB-15 RGB port of the AV video card:
- No video or blank screen
- Wavy glittering lines with no video image
- Machine crashes and has no video on next reboot (restart)
- Machine loses video after a restart. If the machine is shutdown and restarted, the video image returns.
This issue can affect all Power Macintosh AV configurations with any type or size monitor attached to the AV video port.
This issue may occur because occasionally the video driver of a Power Macintosh AV can send out incorrect sync pulses to monitors that employ separate sync lines for the horizontal and vertical sync signals. Incorrect sync pulses may disable the monitor sweep circuits and the video signal fails to function.
To avoid this issue, install at least one of the following software fixes installed:
- PowerMac AV Update (in the extensions folder)
- PowerPC Enabler v1.01 or later (available in System Update 3.0)
These software fixes are incorporated in System 7.5. The presence of both files does not cause any issues in use of the Macintosh.
To install the enabler, you have to reestablish video. To do this, try resetting the parameter RAM (PRAM) or connect a monitor to DRAM-based video using an HDI-45 to DB15 adapter cable. The DRAM-based video port can support monitors up to 17-inches.