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Author Topic: Can't Get Vga To Work  (Read 1207 times)

AnnaOlum

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Can't Get Vga To Work
« Reply #45 on: February 23, 2012, 12:48:56 PM »


Help please? wink.gif




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AnnaOlum

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Can't Get Vga To Work
« Reply #46 on: February 24, 2012, 01:35:33 PM »


Could it be that the LM1881 is incompatible with the X2 5035 and my HDTV?
When the box was softmodded with ndure 3.1 it worked but now with the TSOP flash it doesn't work anymore.

Should I try it with the internal sync mod? What material do I need (except 2x 74HC14) and what does the circuit look like?

EDIT: Just found some infos about the LM1881 which said that I could get real HSYNC out of the chip with a NAND and AND Gate. How does this work?




Edited by AnnaOlum, 24 February 2012 - 11:29 PM.


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xboxmods2977

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Can't Get Vga To Work
« Reply #47 on: February 26, 2012, 01:09:20 PM »


Could it be that the LM1881 is incompatible with the X2 5035 and my HDTV?
That depends. Does it still work with your VGA (PC) monitor after the VGA bios was flashed to the TSOP?




Edited by xboxmods2977, 26 February 2012 - 10:09 PM.


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AnnaOlum

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Can't Get Vga To Work
« Reply #48 on: February 27, 2012, 06:46:03 AM »


Yep, it still works on all PC CRTs and PC TFTs/LCDs/LEDs we have in the house.




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xboxmods2977

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Can't Get Vga To Work
« Reply #49 on: February 27, 2012, 11:40:59 AM »


Yep, it still works on all PC CRTs and PC TFTs/LCDs/LEDs we have in the house.

Then I would have to say yes, even tho I don't know why at the moment. LOL




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AnnaOlum

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Can't Get Vga To Work
« Reply #50 on: February 28, 2012, 07:43:28 AM »


Found this schematic which should combine the Composite signal and Vsync from the LM1881 into Hsync I cannot make head or tail of it.
Can someone draw me a picture of it please or explain this circuit to me and how I can build it?

QUOTE


By adding a little bit more electronics it is possible to make a real HSYNC iput by wisely combining composite sync and VSYNC outputs from LM1881 using the following circuit which consits of two gates:

          |--------------|----------------------  Composite (if you need
it)
          |              |    |-----\
          | |-----\      -----|      \
Composite ---|      \          | AND   |---------  Hsync
            | NAND  |o--------|      /
Vsync -------|      /          |-----/
          | |-----/
          |
          |-------------------------------------  Vsync






Edited by AnnaOlum, 28 February 2012 - 04:49 PM.


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AnnaOlum

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Can't Get Vga To Work
« Reply #51 on: March 22, 2012, 09:43:33 AM »


I recently ordered two samples of the EL1883ISZ from Intersil. This chip has real HSYNC.
Can I use it for VGA Output and how do I do it?




Edited by AnnaOlum, 22 March 2012 - 06:21 PM.


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xboxmods2977

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Can't Get Vga To Work
« Reply #52 on: March 23, 2012, 10:07:43 AM »


I recently ordered two samples of the EL1883ISZ from Intersil. This chip has real HSYNC.
Can I use it for VGA Output and how do I do it?

Looks to me that this chip has the same pinout as the LM1881n. So, you would use/wire it just the same.




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AnnaOlum

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Can't Get Vga To Work
« Reply #53 on: March 25, 2012, 02:18:50 PM »


I was careless and destroyed the chip. Have to wait now til the EL4581 arrives.




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xboxmods2977

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Can't Get Vga To Work
« Reply #54 on: March 29, 2012, 07:48:43 PM »


Looks to me that this chip has the same pinout as the LM1881n. So, you would use/wire it just the same.
Scratch this.

H-Sync is output on pin 7 of this chip, so you would de-solder the line to pin 1 on your 8-pin socket and solder it to pin 7.
Found another one too like this. The GS4981 is also a video sync separator with true H-sync output, but with these chips, it looks like you may need to invert the H-Sync line. Not positive about that tho. Worth a shot.

I just realized that one of the issues with the LM1881 is that it outputs a composite sync signal into the VGA monitors H-Sync line, which some monitors (and HDTVs) will not like. This is one of the reasons why the LM1881 isn't 100% compatible with all VGA monitors. I cannot believe I never noticed this before.  grr.gif
Also a side note, the EL4581 does not have H-Sync out. It is the same as the LM1881, according to the datasheet.




Edited by xboxmods2977, 30 March 2012 - 03:56 AM.


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