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About Javaman

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    Space Invader

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    CT, USA
  1. I did some searching on the game chip MM57100N and ran across a few screen grabs showing the same vertical lines even with different consoles so I guess it's normal for the ones that use this chip. Still kind of curious to know what causes it. There's a japanese site with what looks like a custom homemade version using the same game chip and LM1889N modulator chip packaged into a clear box with video & audio composite outputs. Same vertical lines even with composite. http://www.ne.jp/asahi/shared/o-family/ElecRoom/ElecGame/MM57100N/MM57100N.html
  2. I have this pong console that works fine but I've noticed these thin evenly spaced vertical lines. They're present on all games, channel 3 or 4 and they never move. If anyone has this same console could you check to see if this is normal or not? I'm wondering if there might be a faulty cap but really not sure. Thanks.
  3. First one is the bank switching cart based on the PixelsPast schematic. EEPROM on top, GAL20V8B underneath. Got a bit messy tearing it down looking for the original problem. A jungle of wires but amazingly it all fits inside the case. I added extra DIP switches so I could turn on/off the address lines depending on whether there's a F8/F6/F4 GAL in the socket or just running a chip with 2k/4k games. Game selection just uses one DIP. They hold 128k so its (32) 4k games or (16) 8k games, etc. The second board is the first I made. It's a 2k/4k with inverter for chip enable plus an LED just for fun.
  4. Yes, I had the 0.1uf cap connected to the 5v & GND pins. Honestly, I tried it both with and without the cap & never noticed a difference. It was only after removing the wire from eeprom GND pin to the GND on the cart that my problem was fixed. I still have the decoupling cap but it's connected to 5V on the eeprom with the other leg directly to ground on the cart. Nothing connected to GND on the eeprom.
  5. I fixed my problem. Sounds strange but by disconnecting the ground wire from the ground pin of the eeprom all glitches & flickering disappeared. It had nothing to do with the inverter or speed of the chips. All my Atmel and AMD eeproms work perfectly without a ground wire attached. I even tried this on my handmade 8k multicart based on the pixelspast schematic. That also works better now. Maybe someone has an explanation but I'm glad to have it working.
  6. Hi everyone, I wired up a little 2k/4k multicart that uses a 74LS04 for a CE hex inverter. It works with the AMD 29F010A-90PC and with some minor wiring changes, the smaller Atmel 28C64-15PC However, it will NOT work with the Atmel 29C010A-12PC and I've tried several. Sometimes I get a glimpse of the game screen before it blanks out. An older post http://atariage.com/forums/topic/21851-2732-eeprom-and-problem-with-6-switch-atari/?do=findComment&comment=240804 describes a similar problem (though I have a 4 switcher) and he solved it by using a 7406 inverter. Before I take a chance on that inverter does anyone know what might be causing this problem? I'm trying to understand why it would effect the 120ns chip but not the 90 or 150? I really would like to use these chips since I have a few lying around. Many thanks.
  7. I got the other one working. Turns out it wasn't the crystal (again). It just needed an adjustment on one of the coils. In any case it's fun using these joysticks. I love how insanely thick they are. It's funny how you can hear the RF if you tune your radio to around 100 mhz. Curious to see what maximum range I get while staying within sight. Thanks again.
  8. Some progress to report. Turns out I had a bad voltage regulator. I replaced it so now I've got power but only one fully functioning joystick. The other joystick has a mind of its own unless I directly connect the antenna lead to the back of the receiver. I discovered when I swapped crystals to the working joystick as well as swapping the ones on the board, the problem follows it. Not sure how a crystal could go bad but I'm leaning towards that as the problem.
  9. Thanks so much for the reply. By all means, any info you can share will be a great help. That bit about playing on different units gives me hope then. I'd been told the crystals had to match. They weren't in a box with instructions but I hooked it up just as you wrote. I put in tank Combat so I could see if either joystick works, but I turn on the Atari and the 2 tanks just fire repeatedly. No response to anything I do. On/Off switches have no effect. I'm wondering does this happen on yours too if you switch off your joysticks? Do both joysticks need to be on for just one to work? I can still see from the silver label on the bottom which one is left and right. The joysticks definitely look like an original matched set. I used a multimeter to check the battery leads where they are soldered onto the board and there's power. I checked each pin on the cords from the receiver and those check out too. The green antenna wires also check out. Once again thanks for any insight you might have. I like tinkering around to fix problems like this so I'll stay at it.
  10. I have a set of the Atari brand I got for cheap at a flea market but they're not working. I'm wondering if it might be mismatched crystals. The crystal numbers in the joysticks are 49.830 and 49.890. In the receiver the numbers are 49.375 and 49.435. Can some kind soul with working wireless joysticks confirm that the crystals in the joysticks and receiver should match? I have no serial number labels on the joysticks to confirm they're from the same set as the receiver. Thanks.
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