Videopac / Odyssey2 forum
August 05, 2020, 03:12:30 PM *
Welcome, Guest. Please login or register.

Login with username, password and session length
News: If you have some news and you want it to be shown here, pm Janzl!
 
   Home   arcade Help Login Register links videopac.nl  
Pages: [1]   Go Down
  Print  
Author Topic: Odyssey 2 graphic glitches  (Read 118 times)
rmzalbar
Trying to get the cartridge in...
*
Posts: 3


« on: May 04, 2020, 10:33:42 AM »

This is my first visit and my first post. Hello.

I just restored two Odyssey 2 systems to working condition that my sister and brother-in-law found for me in a pawn shop. We had one as kids, and she grabbed them on sight because she knew I would want them. They came with three games, Speedway/Spinout/Crypto-Logic, Smithereens, Pick Axe Pete, and even a voice module (which works!)

One of them had a bad composite color encoder chip, that I actually managed to find a replacement for. The other one had a broken address line. I was able to diagnose these in one evening each, thanks to the schematic available online. I also had to open the joysticks and gently clean the silver oxide contacts where the membrane plugs into the cable connector. One of them had a broken RCA cable. No power supplies included.

Cosmetically, one of them looks excellent. It has a textured semi-matte finish to the keyboard membrane and decal, and a raised Odyssey 2 logo badge.

The other one has a shiny finish to the keyboard membrane and decal, and a silkscreened logo instead of a raised badge. It also has a different motherboard revision. Cosmetically, this one was pretty torn up. The silver topcase was so scuffed and scratched that much of the silver finish was worn off, and the keyboard membrane was also rather scuffed up with fine to heavy scratching.

After some hesitation, I decided to go ahead and give the topcase a silver spray paint job. I know it's usually best to keep things original, but this one really quite horrible as it was. I carefully masked out a small rectangle around the logo, and lifted off the decal with some heat, and sanded away or filled the worst gouges. I chose a rust-oleum "titanium silver", and it's a bit more silver and metallic than the original but it really came out very nice! I then used a few passes of plastic polishing compound on the keyboard membrane and the decal, and this actually did resolve most of the fine scratches, reducing the appearance of the scuffing by about 75%. I'm happy I took the risk, as it really looks very clean now and the slight color difference around the silkscreened logo that I had masked off just looks like there's a label.

My question now is that I've noticed on both systems that, in games, there is some occasional graphic character glitching occurring. It typically manifests with animated characters where sometimes an incorrect graphic tile is displayed briefly and then is usually replaced by the correct one within a few frames. I also notice that in Crypto-Logic, if you press Clear to clear the board, sometimes it prints a few 9's on the top line.

Since both systems are doing it, it seems like it may be typical behavior. However, I don't recall seeing this as a kid (granted it was a long time ago.) I haven't noticed any game logic issues yet.

Is this typical, or should I be checking for lazy logic ICs or tired 6810 SRAM chip etc?

Here are pics of the repainted and polished one. Too bad I didn't take any before pictures.
« Last Edit: May 07, 2020, 11:33:43 AM by rmzalbar » Logged
rmzalbar
Trying to get the cartridge in...
*
Posts: 3


« Reply #1 on: May 19, 2020, 06:11:56 AM »

I did an AV mod. I based it on the "Video mod version 1.1" but with a capacitor and clamping diode to get rid of the big DC bias. that mod had. The soldering is a bit messy as I crammed it onto a teeny board. I'd like to be able to say "not my finest work.." but I don't usually make circuits, so it probably literally is.

And hey, I was able to keep the RF! Now with an external jack.

Logged
rmzalbar
Trying to get the cartridge in...
*
Posts: 3


« Reply #2 on: May 19, 2020, 06:13:22 AM »

The video looks great, it's just that my phone camera can't deal with a tube TV.
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!