Hitachi CPT-1455 RGB mod

[vol.2]

Originally Posted by ostlar

Hi,
I've got a Hitachi CPT-1455 (NP84CQ/2 chassis) that I am considering doing an RGB mod on, and because this is a hot chassis I plan to use optocouplers like the HCPL-4562.

A couple of notes:

-the little screenshot you provided shows the RGB inputs routed to a "socket." that is confusing to me because a round socket would normally indicate a tube, and this should be an input. what's the deal with that, is it just a wired connector? Is it the correct set?

- " it supports RGB input at 0,9-3V" NO it does not. That is the supply voltage for the Fast Blanking Pin 9. You must supply Pin 9 with something in that voltage range to "turn on" the RGB. The RGB voltage level of this IC is 4Vpp. That's 4 times higher than normal video. If you wanted to RGB mod this set, you would need to build a video level shifter to raise the whole thing up. Texas Instruments makes a whole line of video processors that you might be able to use. The THS7320 is a 4X fixed gain IC for ED content, and it might work for SD, not sure. You can pour through their video amps and look for an SD 4X IC if you want. https://www.ti.com/product-category/.../overview.html

Would probably be a fairly heavy lift, but it could be a fun project as long as you don't blow anything up or electrocute yourself.

Or you could do a composite input hack or an S video hack. I would probably do an s-video hack and go into pins 4&8 (75 ohm terminated to ground) through two legs of the optocoupler mod.

S-video is 95% percent of the way to RGB quality, and you would be highly unlikely to notice the difference between the two in practice. You could maybe do so by taking (very high quality) photos and digitally enlarging them to see the pixels, but you'll never see a difference sitting down on a couch playing a game.

Make sure you do any live testing with an isolation transformer and be careful to observe all safety precautions. You're at your own risk of death, etc, etc.