boosting VGA

[blackevilweredragon]

Not a game console, but hopefully I can get some help on this.

I have a Mac mini, and it's unfortunately one of the bad batches...  It's VGA output is very weak..  The picture is darker than it should be, and it also sometimes has wavy interference lines, depending on the refresh rate...

Some one once said that RGB and VGA should be about .7 mV, but the Mac mini's output is .5 mV..

How can I boost this?  Cheaply, and easily...

[Segasonicfan]

Super cheap solution: Buy or get a free sample of the EL5410 op amp from Intersil.  You can use another high bandwidth video op amp but I have personally had great success with this chip.  It is a breeze to wire for RGB amping, just check out the Genesis section on my site b/c it has all the info there.

If you can't solder well (SOIC) or don't want to source the chip I can make you one for $15 and send it to you.  Just putting it out there as another option, not trying to come off as a sleazy salesman.

-Segasonicfan

[viletim]

High resoultion (say, 1024x768 res) video runs at a very high frequency - bandwidth requirements of over 100MHz are not uncommon. It's not an easy task to build and amplifier for such a signal, even with the latest shit hot op-amps, if you've never done this before.

My suggestion is to buy a decent quality active KVM (the kind that actively buffers the video) and modify the values of the termination resistors inside from 75 ohms to about 100 ohms. Connect it to the mac with the shortest VGA cable you can find (<30cm preferably).

[Segasonicfan]

Ah yes, higher res will give you probs like that.  However, don't you just want to play normal res arcade stuffs?  The opamp should work for that...

-Segasonicfan

[blackevilweredragon]

yes, i like using things that are at VGA sync (480p 60Hz), but i was hoping it could help out on the high stuff like 1280x960 75Hz..

[Segasonicfan]

well, like viletim said, for higher res stuff you'll need to buy an expensive converter or work with a far more complicated circuit.  I obviously don't know much about this though since I never work with hi res stuff so talk to Viletim.  If you decide on 480p talk to me.

-Segasonicfan

[Segasonicfan]

Looks like this would do it all:
http://www.analog.com/en/prod/0,,759_775_A...252D3%2C00.html

QSOP isn't going to be an easy chip size to work with though :/

-Segasonicfan