rgb mod for cdi 220 / 37 found!

Started by acem77, October 20, 2005, 12:31:50 AM

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i was bored and found out i could mod my cdi 220 /37!

i searched and searched google and had no luck on finding any one that had done any rgb mods for cdi.
a few high end cdis do have rgb out and it looked like some euro cdis had a rgb connector.
this gave me a lot of hope that all or most cdis would have the rgb signal in at the mother board level.

i took my cdi apart to see if i could see anything of interest.
as i looked in there i saw a sony cxa1145m ic. then i was like cha ching!
then i hunted down the data sheet on it now i have a super clear picture coming from my cdi.

as always i am running it to my xrgb2 plus and it looks great on my samsung hd tv.

i will post pics and more info later for the full 2 other people out there that care enough about the cdi ;)

the data sheet shows some caps and resistors.
do i need the caps are they used for filters or for safety?
i know i need the resistors the rgb signal is too bright but i have a switch able circuit i installed in my rgb selector box to fix that.


The Sony CXA1145 and friends all require a resistor (to set the output impedance, usualy 75 ohms) and a capacitor (this is to block the dc on the output -- there's nothing wrong with a bit of DC on the output but the CXA1145 is unable to directly drive a 150 ohm load with DC on the output) usualy from 100u to 470u.




The CXA1145 makes lousy composite video but is an excellent RGB amplifier. I have used it in my RGB boxes and in the Nintendo 64 to amplify RGB.

The thing here is that even though the datasheet recommends capacitors and resistors on the output most companies that use the chip don't do it. I recommend the use of 68 to 75 Ohm resistors on the RGB output lines to tone them down if they are too strong.

By the way, Sega uses the CXA1145 on their Master Systems and most of the Genesis units.
Console hacking is like sex. For best results you got to know where to poke.....