Once in a while, when converting older machines to LTSP terminals, you may come across some really old (usually 14") monitors that can't handle the screen refresh rates that come shipped by default with LTSP. However, due to LTSP's excellent design, you can easily substitute in your own custom mode lines for XFree86.
Here are 3 custom modelines which appear to work for some really old monitors. You can either put them in a workstation definition, or in the [defaults] section of the lts.conf file.
X_MODE_0 = 640x480 31.5 640 664 704 832 480 489 492 520 +hsync +vsync X_MODE_1 = 800x600 40 800 840 968 1056 600 601 605 628 +hsync +vsync X_MODE_2 = 1024x768 44.9 1024 1048 1208 1264 768 776 784 817 interlace
If you put these 3 modeline definitions in a host definition, it should look something like this:
[ws001]
XSERVER = ... whatever ...
...
X_MODE_0 = 640x480 31.5 ...
X_MODE_1 = 800x600 40 ...
X_MODE_2 = 1024x768 44.9 ...
As listed, the modelines will start you off in 640x480. You can then use the standard XFree86 keyboard shortcut of <CTL><ALT><KP+> to switch to 800x600, and then 1024x768. Find the highest one that works, or, the highest resolution that looks decent on the monitor, and make that resolution into the X_MODE_0 line. So, for instance, if you wanted to have your monitor boot up in 800x600, with <CTL><ALT><KP+> taking you first to 1024x768, then 640x480, you'd set the modelines like so:
X_MODE_0 = 800x600 40 800 840 968 1056 600 601 605 628 +hsync +vsync X_MODE_1 = 1024x768 44.9 1024 1048 1208 1264 768 776 784 817 interlace X_MODE_2 = 640x480 31.5 640 664 704 832 480 489 492 520 +hsync +vsync