Milmar Dactar Brazilian 2600 clone circa 1983
goal: transcode from PAL-M to NTSC (crystal swap) and add simple composite out amp
notice the lower right of the board.. that's an entire discrete RF modulator, completely unshielded
as per usual, it's our old cheeky little friends at UMC https://mobile.twitter.com/maplesbian/status/1384933252826292225
rather fittingly at age not-a-lot i already patched the end of this RF cable with a yellow RCA cable to fix it, since an RCA plug fits in the switchbox that came with it. since i doubt i'll ever use RF again, i might as well honour my past self reusing this cable for composite
thanks to http://datassette.org i found a schematic that might not be the exact Dactar model i have but close enough to follow where the PAL-M-responsible components are that need to be bypassed
and it's just neat to look at vintage electronics schematics
so two things
- i forgot i'll need another RCA plug for audio as well so i'm likely not using the cable that's already on it since i need two
- i said circa 1983 because that's the year my dad recalled buying this, but looks like from chip date codes this is from around 1988(?!)
so far i've replaced the colour subcarrier crystal and lifted the PAL-M circuitry off. i've also traced where i can tap for power, audio and video signals. now i built a simple 2N3904 composite amp to plug in
this is the neatest perfboard work i've ever done. i hate perfboard
i _think_ everything's wired right... i should've used shorter wires but i didn't want to risk it
i haven't tested any of this yet
HA it works! in colour and rock solid image!
it's a little bit dim which makes me think i'm attenuating the video too much but i'm so tired of working on this i'll just close it all up
it's done. it's perfect!
found out the video being dark was just the contrast knob on my PVM being left low for some reason, and the audio output worked once i picked another spot earlier in the circuit to tap from. now everything works great
this is huge for me because this 2600 is a family heirloom and to make it more convenient to play on the PVM feels like breathing new life into it. i don't have to deal with RF or black/white video on it anymore. it's wonderful
@mavica_again i'll be honest this is wizardry to me, and just as impressive as if someone had done actual magic
addendum: i tried turning up the volume on the PVM and there was no sound either so i think i'm tapping on the wrong place for sound (though following the trace it should be the right place) so i'll shelf this for now but i'll try to tackle these two issues next time