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Re: monitor frequency out of range
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Re: monitor frequency out of range

From a recent Macintouch post:

Date: Tue, 05 Feb 2002 12:08:07 -0600
From: Greg Meece
Subject: RE: OSX & Monitor problem, and partial solution

I, too, found myself in the unfortunate position of having a monitor get out
of synch where I was unable to see anything happening under OS X. I had
hooked up a monitor that OS X assured me could support a particular
resolution and refresh rate. Instead of using the Displays control panel, I
used the menu bar extension (in retrospect, a BAD idea). Unlike the Displays
control panel, there's no easy way to revert to a safer resolution or
refresh rate.

In my case, the monitor could support the resolution I selected, but not at
that rate (although that rate was supported for lesser resolutions). OS X
was taking the monitor at its word, as it were, and just blindly set it at
that combination. Since the screen had "moved" on me, I couldn't blindly
mouse my way back and could not use the keyboard to do this as well. I found
that zapping the pram only reset the resolution of the monitor to 640 x 480
for the first portion of the boot-up sequence; as soon as the status
messages were being displayed, it was out of range again.

If I had OS 9 installed on another partition, it would have been a simple
matter of holding down the option key and booting from that drive. As it
was, both 9 and 10 were on the same volume, so I booted from the OS 9
installer CD. Once there, I set the startup System to OS 9. If either of
these scenarios is not an option for you (e.g., you never installed OS 9),
then you'll have to SSH into OS X and use pico or similar text editor from a
terminal (you did enable remote login, didn't you?). Others have posted how
to do that type of thing, so I'll not repeat that here.

After much trial and error, I found that the file that needs changing is
located at: <[your boot hard
drive]> You can edit this
file ("") with a text editor such as BBEdit.

You need to change three values in order to get your monitor back; the
Height, Width, and Mode. For Height and Width, you need to change the values
to ones you are absolutely certain your monitor will support. You might even
want to be extra-conservative and change them to 640 x 480 (you can always
change the resolution in the monitors control panel - CAREFULLY this time).

1) Replace Height: In the first dictionary array, look for:
<key>Height</key> <integer>NNNN</integer> This is about the 7th key pair
down. NNNN is the current setting for the height of your monitor. Replace
this with a valid value; e.g., if you are SURE your monitor can support 1024
x 768 (usually a safe bet), type 768 where I've put NNNN. <P> 2) Replace
Mode: In the first dictionary array, look for: <key>Mode</key>
<integer>NN</integer> (where "NN" could be any number) This is about the
11th key pair down. Just delete the number itself, leaving the tags
(<integer></integer>). OS X should fix this for you when you reboot. <P> 3)
Replace Width: In the first dictionary array, look for: <key>Width</key>
<integer>NNNN</integer> (where "NN" could be any number) This is the last
key pair for this section. As with the Height section, replace this with a
value you know your monitor can support. If you are using my first example,
you would type 1024 here.

You can now safely set the startup back to OS X and restart. OS X will try a
"safe" refresh rate (perhaps 60 Hz) at the resolution you've set it to in
the previous steps. If that doesn't do it for you...well, sorry. There's
always reinstalling!

Greg Meece

> From: Dwight Johnson <email@hidden>
> Subject: monitor frequency out of range
> I have a viewsonic 17" montior that handles 85 MHz fine connected to
> a G4 running OS 10.1. The problem is that if the computer is
> restarted the monitor will display a warning the the signal frequency
> is out of range. and Nothing comes up. If I start the computer with
> the monitor disconnected and then connect it up after the startup is
> completed it works fine.
> I've tried logging in the system at root as well as other users and
> changing the monitor to a lower resolution and frequency but I still
> have the same problem on start up.
> I've had similar problems with older systems before but the above
> procedure always fixed it.
> Can someone tell me how to fix this issue in OS X?
> BTW I went to to look for a solution there and
> noticed that they started charging about 2 weeks ago.
> Dwight

Robert J Rust
Microcomputer Support Specialist
UW - River Falls IT Services
(715) 425-4357
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