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About ruthsarian

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  1. for what it's worth, I finally got this mod to work for me. I followed the circuit changes noted by Shockwav3, but found the output voltage was too high. I used a 2N3904 for the NPN transistor and replaced the 75ohm resistor between the transistor's base and 5V with a 2.1K resistor. That fixed the signal for me. I further altered the resistor values based on a composite video mod for the Magnavox Odyssey I'd seen and replaced the 100 ohm resistor on the emitter with a 510 ohm resistor and also added a 22ohm resistor in series with the composite out. I then further bumped the 2.1K up to 3.3K. I have no clue if this is "correct", but it works for me.
  2. late to the game, but i would definitely be interested in buying one!
  3. I recently picked up an Odyssey that was missing its game cards. At first I was trying to design a PCB where I would add solder bridges to create a permanent version of each game card. Then I saw this thread and realized I'd missed the obvious: dip switches. So I took a shot at making my own and it works! Awesome idea!
  4. Although perhaps not for the proto cart, but I've had a lot of luck opening 5200 carts by just banging on the top of it with a rubber mallet or the rubberized handle of some other tool. Haven't cracked a case or broken any clips yet.
  5. I picked up a VCS adaptor and opened it up. On the back of the PCB are a blue and a red jumper wire. Two traces on the PCB connecting to pins 15 and 16 of the 2600 cartridge slot were cut and then these restored with jumper wire. Does anyone have any idea/history on what this is? It looks very much like this was done at the factory. My only guess is it's to bypass part of the trace, but I don't see why that'd be needed; I see no vias along the portion of the trace that was bypassed. Just curious.
  6. Based off the attached schematic (the only C-100 schematic I've ever seen) I lifted one leg of the diode at CR6 to essentially remove the RF modulation bit of the circuit. I then tried plugging the cable from 'R.F OUTPUT' (which should now be composite out) to the composite in on a TV and... nothing. I then tried pulling C29 and C27 and running a wire directly from L2 to 'R.F. OUTPUT' and still nothing. I'm guessing the composite signal needs to be amplified, but I've got no idea where to begin with that.
  7. I picked up a Tele-Games branded Pong console and was thinking about doing a composite video mod too. Attached are some pictures from inside the console. Looks like I need to desolder the shield covering the solder side of the PCB, which I imagine will be a headache with all that thermal mass. I'm still trying to figure out a plan of attack for the mod. I want to be as non-destructive as possible so the mod could be reverted one day if desired. I'd like to continue using the RCA cable that came with the system (it's nice and long), but the RCA jack on the PCB means I'd have to either cut and strip one end of the cable or probably cut/rewire traces on the PCB. So I have no clue what I'm going to do and am still thinking on it. As a side note, the security screws to open the case are "holt head" screws. I only found one driver online for holt head screws, it's called an "HY-50" screwdriver. I picked one up and while the bit is correct, it's too deep and won't grab onto the console's screws unless you file the thing down about a 1/2mm. And at $15-$20 range, it's not worth it. You can unscrew these things with pliers or a U-shaped "spanner" bit and a bit of perseverance.
  8. I did. I attached a wire to R50 (second to last pic) and then attached the capacitor to that wire. If you look at the first image that shows the whole board, you can follow the white wire from R50 to this lump underneath some yellow heat shrink tubing. That lump is the capacitor. I didn't want to solder the capacitor directly to the POKEY (no reason you can't do that) and found R50 on my board (early 4-port) is the 1k resistor in the diagram. I added the wire from R50 so I'd have some flexibility in moving the wire rather than just soldering a capacitor leg right to the board. I could have put the cap right on the RCA jack instead, but I didn't think ahead and had already wired the jack up at that point. And I could have perhaps crimped the female Dupont connector pin directly to the cap's leg, but I felt more comfortable adding a couple inches of wire between the leg and the connector. So what I did works, but I probably made it more complicated than it needed to be.
  9. I picked up a 5200 s-video mod board from ElectronicSentimentalities off eBay and installed it over the last couple weekends into my 4-port 5200. I first installed the power mod from console5.com since the video mod bypasses the RF module and that's where the power comes in on the 5200. I decided to mount the video and audio ports on the little door covering the accessory edge connector. To make life easier (in the long run), I made the audio and video cables pluggable to the video mod board. The video cables running from the mod board to the A/V ports came out of an old custom mixer that was being thrown away at work. The cables are shielded and carry a red, black, and bare wire. I just used the red and black wires, so I used three of these shielded cables (composite, chroma, and luma). These cables were very stiff and difficult to shape/direct. If I were to do this again I'd use much more flexible cable. I first tried using female machine pin headers to connect to the GTIA that way if the GTIA goes bad or I need to pull the mod board I don't have to break out a soldering iron. Unfortunately the connection, especially on pin 31 which is all by itself, was problematic. In the end I just soldered the wires to the GTIA pins. The cable from the GITA to the mod board is a little longer than it needed to be, but I wanted a little slack. The direction say you should keep the wires as short as possible to reduce the chance for interference with the signal. I'm not sure if the extra length hurts the signal at all, but it looks good to me. I pulled the RF module, the PCB-mounted RCA jack, and a few other components in that area that are no longer necessary with the video mod in place. Early on I was thinking I might try mounting the mod board there and wanted to free up some space, but ultimately decided to mount it where everyone else who has done this mod mounted it. I may try mounting it there in the future, but I'll need to make a shielded cable to carry the video signals from the GTIA to the mod board. Perhaps something similar to what's there now, just wrapped in copper or aluminum foil tape. Audio taps into resistor R50 and for ground I tap into a ground trace shared by R14, R12, and C18. I made a little plug for this cable as well. The mod kit comes with two RCA jacks even though the 5200 does not do stereo sound. I installed both RCA jacks, connected the audio wires to one RCA jack, then wired the second RCA jack to the first. The sound works great. The mod board needs 5 volts so I found a filled via in the middle of the board that was on the 5v rail, sucked out the solder, and stuck a pin in there. I did the same for a ground point in the middle of the board. I've mounted the board over the ANTIC and U1 and U4 chips. Since the ANTIC can get fairly hot, I put a couple small heat sinks on top and mounted the video mod board to the heat sinks using some double-sided tape. And since the board is between the ANTIC and U1/U4 chips, there's room for airflow underneath to (hopefully) not trap hot air and create problems. With everything connected up I plugged it into my TV, fired it up, and amazingly it worked! The composite video signal is a hundred times better than the RF signal. Unfortunately I don't have s-video in on my TV, but I did have an S-Video USB stick and tried it out on my computer. The s-video signal is 100 times better than the composite signal. The image is crystal clear. Very cool! Now for some pictures! Here's an example of what it looked like before the mod. I used Popeye because that's the game that I've found creates the most noise/distortion. And here's the composite signal on my TV after the mod: Here's a view of the entire, modded PCB: Here's the wired-up A/V harness: And a close-up of the A/V jacks: A close-up of where I tap into the audio on the PCB: And a close-up of where I pulled 5 volts for the mod board. The ground pin is in the back.
  10. That's it! I put in Super Breakout and it works! Thanks! The movement isn't too precise. I've ordered some replacement bearings and I'll see what I can do to clean the shafts. I need to rig something up to keep the PCB in place. Two of the three pegs that hold the PCB in place and align it with the two encoding wheels have snapped off. If the PCB is even 1mm out of alignment the wheels rub against the optos. I was thinking I might try velcro or that velcro-like stuff used to hang pictures on the wall. Is there any way I could replace those pegs? Maybe if I can find some bit of plastic that's the right width I could use a super glue/baking soda mixture or plastic weld. Any suggestions?
  11. You've got a few options for replacement optos. A lot of the trackballs uses in Atari arcade games use this very same opto (but not all!). You could pick up a used trackball from an arcade parts warehouse or off eBay and pick the optos off the board. You could also get lucky and find someone selling them individually, but that seems to rarely happen. You could also use modern replacement optos. I haven't done this, but my guess is you could pair two of these optos (or maybe two of these, or something similar) together to replace one Atari opto on the PCB. The Atari opto is basically two optos in a single package. So using two single optos should work. I got lucky and found the same model optos used in the 5200 track ball. If I hadn't found those, I would have tried using the modern optos from the link above.
  12. I picked up a CX53 track ball that was non-functional. I opened it up and found one of the opto's had been removed by a previous owner. I replaced both optos as I had no movement in the direction supported by the existing opto on the PCB. I now have movement in both directions, but it seems like the track ball comes back to center after. My question is: is this normal? To test the track ball I've used Kaboom! and also plugged it into my PC via a 5200-daptor and used the game controller setup in Windows to monitor the track ball movement. I measured the voltages on test points 9 and 10 (vertical and horizontal pins connecting into the 5200) and they hover around 2.2v when the ball isn't moving, then change +/- .5v depending on what direction the ball is moving. I've followed the troubleshooting guide in the Atari 5200 service manual and everything matches right up to the point where it talks about TP9 and TP10 presenting a "ramp waveform". I don't get that, I have a solid line at around 2.2 volts on both lines. The cap (C7) is asks to check if it's shorted is not. The resistor (R21) is asks to check if it's open is not. And it's the same for their equivalents on the vertical. Which drops me into "replace game cable" in the troubleshooting guide. That is something I don't have and probably won't be easy to come by. I also have some doubts that the cable is bad... i suppose I could use a 5200 joystick cable and hack together something to test just the motion PCB. Maybe I'll do that this weekend. But does anyone have any insight or suggestions as to what might be the problem (or even if there is one? does the trackball only work on games that know to look for one?? which wouldn't surprise me as I'm a total noob when it comes to the track ball). Thanks
  13. I'd be interested! I just picked up a copy of Space Shuttle Simulator and was thinking of printing something out on paper, but this would be way better.
  14. Section 4.14 of the 5200 FAQ has instructions on how to build a simple replacement RF adapter. Check out this thread about someone else building a box.
  15. I picked up a second 5200. This one had all the screws in it and signs that it was never opened before. The two screws beneath the joystick holder area are 1/2 inch #6 sheet metal screws. The others are 3/4 inch. I picked up replacement screws at Home Depot and they work great. The second 5200's motherboard has no work on it at all. The cap between pins 1 and 17 on the POKEY is not there, nor the extra wire between pin 1 on POKEY and ground on C104. nor any of the other, non-VCS mod things over on the right side. I'm still curious what they do. The second 5200 was displaying a garbled screen almost as if it had bad/no sync. I plugged in several carts and nothing happened. However when I plugged in Q-bert, I could start a game and the Q-bert and monster sprites appeared on screen, clean, over the garbled background. So it wasn't a sync issue nor a CPU issue. I swapped out the GTIA and ANTIC chips from my good 5200 into the new 5200 and found it was the ANTIC that was bad. I'll order a replacement from best electronics. One thing I did notice is the sound was a little blown-out on the new 5200. I'm wondering if that POKEY mod might have anything to do with fixing that. But before I risk a $20 POKEY, I was curious if anyone might have any insight into the non-VCS mods I mentioned in the first post. I'd like to think they're documented somewhere if they're (as I suspect) factory mods.
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