TITLE
    Power Macintosh: No Video With AV Video Card (12/94)
Article ID:
Created:
Modified:
15608
6/13/94
12/14/94

TOPIC



    This article describes a problem with Power Macintosh AV configurations and the loss of video sync with monitors attached to the DB-15 port of the AV video card.


DISCUSSION


    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 problem can affect all Power Macintosh AV configurations with any type or size monitor attached to the AV video port.

    This problem 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 problem, 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 problems in use of the Macintosh.

    To install the enabler, you have to reestablish video. To do this, try zapping 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.


    Article Change History:
    14 Dec 1994 - Added keyword and 7.5 reference; made minor technical updates.

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Document Information
Product Area: Computers
Category: Power Macintosh
Sub Category: General Topics

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