Help with Genny 1 Composite video...

[Peyn]

Hey there. Today, I just pulled the composite video straight off of the genny's cxa1145 chip, and it is all bright and shitty. Can someone help me come to a solution for this problem?

 

[ExCyber]

From the reference circuit diagram in the CXA1145 datasheet, it looks like you need (ordered from closest to the chip to farthest):

- A 470uF capacitor (inline); this probably removes a DC offset, so I don't think the exact value is that important, but that's what is shown in the datasheet

- A 75 ohm resistor (inline)

- A 75 ohm resistor (to ground)

 

[Peyn]

Ok, so a 470uF cap and a 75 ohm resistor in the compositle line, and then a 75 ohm resistor in the connecting the ground cable of the composite cable?

 

[ExCyber]

The last resistor is connected between composite-out and ground. Most encoder circuits I've seen (not based on CXA series but rather old Motorola and Analog Devices chips) don't have this resistor at all (only the capacitor and 75ohm inline), but since I can't read Japanese I can only tell you what's on the diagram...

 

[Peyn]

Like so? Thanks for your patience.

 

[ExCyber]

The cap should be the first thing on the output, if memory serves (didn't save a local copy of that datasheet <_<)

 

[Peyn]

Thanks again, and here it is: cxa1145

Actually, the cxa1145 seems to have the resistor already in there. Thanks for your help.