Got a curly one that has me completely stumped.
I have an old HP nx6120 laptop that had its screen replaced
( I keep it as it has a real COM and LPT port )
The old screen was SXGA+ ( 1400 x 1050 ) and the new one is a UXGA ( 1600 x 1200 ), ie still a 4:3 ratio but finer resolution.
On booting up now, the lappie only reports that 800 x 600 ( SVGA ) or 1024 x 768 ( XGA ) are available resolutions.
I then plugged in an old 16:9 screen to the VGA port, and lo and behold, i now have access to all the resolutions up to 2048 x 1536.
On selecting any of these, the external and lappie screen both go to that resolution, so i know the lappie screen is capable of this resolution, ie up to 1600 x 1200.
I also found that the external monitor doesnt need to be powered, just connected to the VGA port for this "trick" to work.
This is a pain in the @r$e as i need to connect the external screen to the VGA out after booting the lappie in order to get the lappie screen to go to the required resolution. ( I can then unplug the external screen )
Soooooooooo, how do i force the lappie to read the new screen capabilities without needing the external monitor??????
I am out of ideas.
Have you tried the trick with just the vga cable attached to the laptop and the other end not attached to anything?
Never heard of a null-monitor before so dont know if knocking something up will work as well. I'm guessing its "reading" a voltage change on the vga port indicating its plugged in but it may need grounding to work. Personally I'd grab a 15(?) pin din connector from jaycar (well a couple to experiment), chuck in a resistor on a voltage pin and connect to ground or the shield and see how that goes OR ground all the data lines (leaving voltage alone).
have you tried:
go to Control Panel > All Control Panel Items > Display > Screen Resolution (or right click on the dektop > Screen Resolution) > Advanced Settings > Monitor:
clear the box Hide modes that this monitor cannot display and Apply.
the monitor.inf file tells the os the hardware spec so i guess your lappy doesnt know anything about the new screen, its still reading the old monitor.inf file. (You could set a restore point, backup any monitor.inf files you can find, go to device manager and uninstall the display device. set display to lowest resolution and reboot and see what happens. Every monitor needs to handle the default vga screen of bios so it should work. the display adjusters apply to the primary monitor and when you plug in an external it assumes you are using that, it doesn't know anything about the new internal panel or its specs, gfx chips play no part in this. there may be registry hacks or possibly taking the monitor.inf file from another laptop (more recent) and see how that goes, of course lcd pixels are fixed dimensions so you may or may not have display issues with this.
The "trick" doesnt work with a simple cable, the monitor has to be connected, but the monitor doesnt need any power.
As to settings, yes i have tried.
The lappie reports 2 monitors "default" and "Plug and Play",
default only allows the 2 resolutions i listed, the other shows about 16 settings, but only the 4:3 ones work properly,
however, i cant "save" the settings for the session unless the external monitor is plugged in when i do the "apply"
I will double check the monitor.inf, but my old screen could do SXGA+
and i currently cant even select that unless the external monitor is plugged in.
All good fun
I would be trying to make a null monitor connector if myself
probably some cautious application of fist to monitor too.
does the lappy *need* to be portable? Would using external just be viable? (maybe remove old screen completelyand sit base against external monitor? I know you replaced the internal monitor but in my experience most laptops sit permanently on a desk anyway.
You've obviously tried the lappy Fn buttons? typically marked in blue where you hold down the fn key and press the key with the blue symbol you want. You can usually cycle between combinations of laptop/external mointors in on/off states etc. Maybe if you get it to recognise the external as primary and disable internal completely you can store settings?
As i noted, i can see the resolutions but cant "apply" them,
ie when i boot the lappie with nothing attached, i still have 2 "monitors" appearing in the setup, but i cant actually apply the settings for the one that shows all the resolutions.
Quote:
does the lappy *need* to be portable?
Yep. Its what i use when i go interstate or to other places, as by having the LPT port, i can run my logic analysers etc.
Quote:
You've obviously tried the lappy Fn buttons? typically marked in blue
Yep. On booting, even with the external monitor plugged in, i only get the lappie screen. I then use the "blue" buttons to clone the lappie screen to the VGA port as well. Its only in that mode that i can set the resolution, and when done, it applies to both screens.
Unplugging the external screen does nothing, ie i can keep working at the high resolution, but if i then cycle through the "blue" buttons again, it reverts to the low resolution.
Disabling the lappie screen isnt really a good choice as i would still need an external monitor, and if i have that, i can simply set the lappie and then unplug, making it simpler to use.
All good fun
From what I can find upgrading a laptop screen isnt really a "thing", they are designed with the VGA/HDMI outputs for people wanting better screens etc. Each display panel (laptop screen,desktop monitor, phone screen, whatever) has its own controller chip and default configuration for the initial behaviour, but not exactly a standard across all manufacturers. eg a recent arduino project I put together had an lcd sreen and displaying text it did so in japanese until I researched the panel, found the command needed to get it to use the english character set, even then i had to do display more special characters which it stored in a different character set. So it could be the laptop hardware is talking the wrong language to the panel, nothing to do with bios or windows. For a panel intended for a monitor it makes sense the common resolutions share the same command (more mine i had to convert a binary chart to hex values, not as simple as just telling it "english" or in your case a resolution number). If the laptop was in a range that came with different panels then the control might allow you to switch panels successfully. In your case the lappy may predate UXGA so maybe not so lucky.
Really dumb question: why not get a serial to usb converter (not adapter cable). It emulates the port for those programs that talk directly via serial. I had to use one for some telescope gear as my laptop with serial died and the only ones I have left are too ancient to run the software.
Can't recall the brand off hand but works a treat.
Disclaimer: dont read further unless you are prepared to buy a replacement lappy if it goes wrong.
I havent tried this and if it blanks your screen in an unusable resolution I take no responsibility. But hacking the registry might do the trick.
I'd do this with the external monitor connected and make sure you can switch to it and back easily at any time. if you lock the laptop into a resolution it doesnt like your only hope is to use the external display to help you edit your way back out again. Take a backup/export the registry key(s) you change so you can double click the *.reg file and put things back. Possibly via safe mode.
why not get a serial to usb converter (not adapter cable). It emulates the port for those programs that talk directly via serial.
I have several of them, but its the LPT port that is critical.
I actually use a low level assembler loop to read the port and write the data out to a string for my logic analyser.
I can get about a 1.5us granularity like this as long as i up the process priority as well.
Putting any "adapter/emulator" in the path kills me.
Hi Andrew,
The issue might be EDID related. This is how the graphics card and the monitor basically do their handshaking to set resolution etc.
It looks as though, you have generic monitor drivers as you mention they are listed as 'default' and 'plug n play'.
When I get a new monitor, it usually has a disk with it with a small driver for the monitor on it. Once installed, instead of showing plug n play etc, it will show the actual brand of the monitor so you know it has been loaded. Windows is usually good with its own drivers but not all the time.
Generally with EDID what happens is this: Before anything is displayed on the monitor, the graphics card will ask the monitor what its native resolution is, the monitor will then respond with its native resolution and if the graphics card can do that, it normally should work and you will see on screen. If the native resolution is not supported, both devices will attempt to negotiate a resolution that will work for both.
So if possible, update the graphics drivers from the manufacturers web site, (some people's PC's have only windows default drivers installed which are not as good as those from the manufacturer), and try to source the monitor driver.
In some cases I have seen, the manufacturer gets the EDID wrong and that will cause headaches.
Not 100% sure on this next bit, but I think the EDID circuit on the monitor that was not plugged into power gets its power from the PC via the VGA cable which completes the circuit and retrieves the EDID info that way. This may explain why it works in this setup.
Got a curly one that has me completely stumped.
I have an old HP nx6120 laptop that had its screen replaced
( I keep it as it has a real COM and LPT port )
The old screen was SXGA+ ( 1400 x 1050 ) and the new one is a UXGA ( 1600 x 1200 ), ie still a 4:3 ratio but finer resolution.
On booting up now, the lappie only reports that 800 x 600 ( SVGA ) or 1024 x 768 ( XGA ) are available resolutions.
I then plugged in an old 16:9 screen to the VGA port, and lo and behold, i now have access to all the resolutions up to 2048 x 1536.
On selecting any of these, the external and lappie screen both go to that resolution, so i know the lappie screen is capable of this resolution, ie up to 1600 x 1200.
I also found that the external monitor doesnt need to be powered, just connected to the VGA port for this "trick" to work.
This is a pain in the @r$e as i need to connect the external screen to the VGA out after booting the lappie in order to get the lappie screen to go to the required resolution. ( I can then unplug the external screen )
Soooooooooo, how do i force the lappie to read the new screen capabilities without needing the external monitor??????
I am out of ideas.
Gday Damien
Hmmm, if the previous EDID data was true, then i should still have the old XGA mode loaded via the driver, as thats what the original screen supported. ( The new screen also supports it )
The Plug and Pay and Default selections both reference the same chipset
ie "Mobile Intel(R) 915GM/GMS,910GML Express"
however
Plug And Play only allows the VGA and SVGA options
Default "appears" to have all the options that were available in the last external monitor i plugged in.
I can always select/save a resolution from Plug and Play
I can always select any resolution from Default but on hitting Apply, it defaults out to SVGA unless i have an external monitor plugged in.
Will dig more into this EDID override stuff, but it may take a few beers :-)
The new monitor will have its own EDID which the computer does not know until it is plugged in.
The computer through its graphics card will then communicate with the monitor via EDID to determine a native resolution of the monitor. Fine if it can do it and if not then it will re negotiate a resolution supported by both. This may be what you are experiencing.
I think in your case, the EDID of the new monitor or 'plug and play driver' is not quite correct and therefore not allowing higher resolution when used as a stand alone monitor.
When you plug in an external monitor, the system may use the external monitor's EDID and then that may explain why your new monitor works in conjunction as its using a different EDID to what it has.
It sounds as though the driver to talk to your monitor is a default Windows one and when it talked first time to the new monitor, it did not get it correct.
I've just had a look at my work PC and when looking at the 'Windows' display settings, the display has the exact model of the monitor that's plugged into it and therefore has the correct EDID. This was a result of using the supplied disk that came with the monitor. Otherwise it shows up as 'Plug n Play'. Same for my computer at home, I build them myself and load everything.
Let's say your new monitor came with a disk. If so, after you install it, you would see the display listed as the model of the display and not 'plug and play'.
That would mean that Windows would be using the new monitors driver to talk to your new monitor and not the generic Windows one.
I mentioned to update the drivers for the graphic card if possible as that can sometimes help as well as they all interact with each other. Can't hurt.
Gday Damien
Its all good fun
So far it looks like the new screen is a Seiko Epson SEC5044
with max resolution 1600 x 1200 ( from device mangler )
Even when nothing is plugged in, i also see 3 "Monitors" under device mangler in the monitors section ( not the graphics driver section ) so not sure if deleting them and reinstalling will help :-)
Chasing drivers for SEC5044 shows several different manufacturers ( other than Seiko Epson ) and also different resolutions, so not sure i want to load them yet. Also, most are for W7/W8 not XP32 SP3
Will try the EDID reader and see what it gives
Gday Damien The EDID reader program gave me the clue.
I mentioned above that when the screen was working, device mangler was reporting the screen ID as an SEC5044, but it lied :-)
Ref the dump from the EDID reader.
The three marked with the # are what was being reported.
When activated by plugging in the external monitor, the "active" internal monitor now became an NEC61BE, which translates to an NEC Multisync FP1375X (Analog)
Note!, all other models ( which includes data for all the external screens i have used to date ) list 3 times, but the NEC only had 1 listing???
Ignoring that, i then found a driver for the screen and went to device mangler and simply reset all 3 instances to the NEC driver, and viola, it all works.
Many thanks for the breadcrumb trail.
The EDID reader program gave me the clue.
