Thank you

[cskordis]

Thanks for allowing me to join.
I’m from Austin, Texas with a passion for retro 8bit computers especially based around the 70’s RCA CPU CDP1802.
I have even designed one that runs CHIP8.
And this is the reason why I joined. There is nothing like a CRT displaying those 8bit images.

I have successfully converted an Emerson 5” Color set from RF to RCA composite but have failed to convert a GE space saver 5” 7-7650B. What is puzzling is that the circuit from both are very similar but doing the same hack doesn’t work.

Have any of you had any success?


Costas

[luRaichu]

I, too, was attempting the same hack on my Sony Watchman FD-510 many months ago. I remember it uses the same chipset as most other 5" B/W sets of the era. The hack for these is to cut the VIDEO OUT trace from the main IC and feed your composite in through there directly to the TV. But when I did this myself I got retrace lines and a dark band on top of the screen.
Never figured out the fix so I bodged it back together and it's sitting in my storage unit now. One of these days I'll have to take another crack at it.

Also, why didn't the manufacturers just include connectors for composite input on these things? My Craig PC570 has them and it works just fine. You can even get composite output from the tiny tuner.

[electronjohn]

Welcome to VK!

[Alex KL-1]

Welcome aboard!

About the video inputs, the issue is more complex when the set have DC coupling between stages (eg. from video demod. to sync separator). This needs to be accounted for, the bias for next IC's. And the amplitude of the signals. Even a mundane IC from the late 70's normally outputs more than 2Vpp of signal, and the modern video is only 1Vpp... some sync separators don't like that.

[Dude111]

Welcome to the site!!!!!