Another HDMI - VGA issue ?


12 posts
by Morph » Thu Jun 28, 2012 6:03 pm
Hi - first post so apologies if this has been done to death...

Don't have a HDMI monitor only the big telly which is on SOAP opera watching duty most of the time, so I bought one of these which is on the WIKI as working

http://www.amazon.co.uk/gp/product/B007KEIRNG

And it did. When the Pi arrived I turned it on a couple of times and it booted and worked OK on a VGA monitor. I got busy at work so I had to leave it for a couple of weeks, now when I plug it in I get nothing on the display. The Pi is working - I checked it on the HDMI telly when SWMBO was out - and it was working with the same adaptor previously on the same monitor.

The monitor does "wake" as though it is getting some kind of signal but nothing is shown.

Do the display adaptors fail a lot, is there one which is much better ? Is there something else I can try ?

Thanks.
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by Burngate » Fri Jun 29, 2012 7:55 am
From your description, it did work. Since the monitor now wakes up, I would think it is still getting H and/or V syncs, just not R,G,B, so it is atleast partially working.
Several things could have gone wrong.
To get the syncs out, a lot of the electronics has to work, and losing all three of the R,G,B A-Ds seems unlikely.
It isn't clear from the Amazon page - does it need a VGA-VGA lead or does it plug straight to the back of the monitor? If it needs that lead have you another you can try?
Are you sure the VGA connection is screwed home properly?
And a final question - does the monitor still work - can you try a different source? Or a different VGA monitor?
And finally, could the Pi have decided to use a different mode, one which the monitor won't support?
Wyszkowski's Second Law: Anything can be made to work if you fiddle with it long enough.
Brain surgery is easier than psychoanalysis
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by Morph » Fri Jun 29, 2012 8:39 am
Thanks for the reply. The monitor is used by another PC so I know it works ok. Thinking the HDMI adaptor had failed I plugged it into my work laptop's HDMI output and it worked fine.

The image I'm using is the original debian with no config changes.

Everything works...but not together any more :(
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by dom » Fri Jun 29, 2012 8:44 am
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by Morph » Fri Jun 29, 2012 6:43 pm
OK - Because I'm impatient ;) I thought I would try that line in a new config.txt in the root of my SD card - followed the instructions to add that to the card using my (Win7) laptop. Put back into the Pi - not booting at all...

So downloading wheezy - will try that now and see what happens.
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by Morph » Fri Jun 29, 2012 6:50 pm
OK - following instructions from DOM I now have something on the screen so - woooohoooo!

Many thanks. :P
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by Morph » Sun Feb 03, 2013 3:32 pm
Hi,

I know this is an old thread but I'm only just getting back to using my Pi now. I have an L204WS LG display capable of 1680x1050 and a HDI-VGA converter but all I can get is blurry characters and a large black border at the top and bottom, but not left and right.

I'm kind of close to giving up unless anyone has any suggestions. I've tried different overscan values (negative), disabling overscan, and changing the group etc. to something else.

Any ideas, anyone else using this display and can give me the magic spell ?

This is kind of where I gave up with Linux in the mid-90s until they got the screen size / resolution thing sorted out...

Cheers
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by Morph » Sun Feb 03, 2013 4:13 pm
More fiddling suggests that I just need to find a resolution that the Pi, the HDMI-VGA "thing" (I don't know where it came from as my original one was "borrowed" by Mrs Morph for her work Windows 8 Ultrabook) and the monitor all agree on.

So my basic settings in config.txt are :
hdmi_safe=1
disable_overscan=1

overscan_left / right / top / bottom = -30

framebuffer_width (as below)
framebuffer_height (as below)

hdmi_group=1 (VGA)
hdmi_mode=1 (VGA)

Text mode attempts with the framebuffer size

Tried 1024x768 and it seems OK but fuzzy as the text seems large.

1400x1050 is very fuzzy.

1280x1024 has a space on the left and right - fuzzy

1280x768 is just like 1280x1024 but with a border top and bottom

1440x1024 screen full but blurry

1440x900 same as 1024 but border top and bottom.

1440x800 same as 1024 but larger border top and bottom.

1440x768 same as 1024 but even larger border top and bottom.

At this stage I think it might be the class - apologies if this is known, I am new to this...
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by Burngate » Sun Feb 03, 2013 4:56 pm
I think your present problems stem from
Code: Select all
hdmi_safe=1
which tells the Pi to ignore a lot of the HDMI configs.

Now you need to comment out that line (put a # at the start), and experiment with the hdmi_group and hdmi_mode lines

Also, the line
Code: Select all
disable_overscan=1
tells it to ignore the subsequent overscan lines, so that could be commented out to square everything up.
Wyszkowski's Second Law: Anything can be made to work if you fiddle with it long enough.
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by drgeoff » Sun Feb 03, 2013 6:41 pm
From your description of the monitor it seems to have a 1680 by 1050 panel. If that is indeed the case then you will only get a pin-sharp display by having the RPi output that resolution and the HDMI to VGA converter not change it.
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by Morph » Sun Feb 03, 2013 6:45 pm
After a lot of messing around I have disabled the hdmi_safe=1 option, and selected hdmi_type=1 and hdmi_mode=31 which seems to get me a hi res display, except I can't see it because it is off to the left.

So I disable the disable_overscan=1 option and start playing with the overscan_left,right etc. options.

TBH they seem to leap all around every time even if I change only one at a time. I often have to play with my screen's scrolling options to be able to see the left hand side. And if I go into LXDE then I often can't see the right hand edge.

IMHO this seems like a lot of messing around just to get a screen picture.
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by Morph » Sun Feb 03, 2013 6:58 pm
drgeoff wrote:From your description of the monitor it seems to have a 1680 by 1050 panel. If that is indeed the case then you will only get a pin-sharp display by having the RPi output that resolution and the HDMI to VGA converter not change it.


I've tried the full resolution in VGA mode but no joy. Now into the depths of the HDMI modes which also seems naff.

Maybe I should just buy a new telly... :roll:
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