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Bluebass

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Posts posted by Bluebass

  1. Posted

    I guess I could start... I ended up buying another system last night because I didn't feel like fooling with my Junior anymore.

     

    I bought the Junior With 10 commons and 2 original sticks for $25

     

     

    I paid $30+shipping for my Vader with 2 third-party sticks, two originals, a set of paddles and 8 games, some of them I already have.

     

    What did everyone else pay???

  3. Posted

    Would you send me the bad one? :D

     

    My dad works on Mainframe computers, and used to test circuit boards for his company. I'm giving it to him. He screws around with stuff like this when he's bored.

  7. Posted

    You've probably got a bad 4050 then. Try replacing that chip or bypassing the ciurcut traces for the two firing buttons. As far as the composite mod, you'll be much better served with Ben Heck's second mod using a transistor. This mod is compatable with more TV's than the first one ever was.

     

     

    Do you have a link to his second mod? And where can I get a 4050. I've looked at some electronic dealers and can't find one.

  8. Posted

    Ben Heckendorn did eventually succeed in miniaturizing a Junior motherboard (the rare single-chip version) but then accidentally fried it. The proper method for a Junior will be different than for a 4-switch, and I don't think you can get a Junior down to a neat 4-inch square without a few extra circuit sections patched back onto it.

     

    If you're using a Junior, you're gonna be almost on your own, so at the very least you should have some good close-up photos of both sides of the board before you hack it, and save everything you cut off, in case you have problems so you can trace out the circuits to see what you broke.

     

    Your color problem sounds like you have the resistors connected wrong, and are not getting the proper luma levels. Are you using Ben's first composite mod, or the second one (with a transistor)?

     

    Another possibility is that you're using the wrong mod. Where do you live? Most of the half-dozen or so mods on the net, including both of Ben's, are for NTSC consoles only. The PAL TIA has a different pinout. If your Junior is PAL, then an NTSC mod will not work.

     

    The fire button signals on the Junior go to a 4050 buffer IC, then to the TIA IC (the 40-pin farthest from the cart port). Are you sure you didn't cut their tracks, or the tracks to their pullup resistors?

     

    I'm not making a portable. I don't think it is the mod either. I pulled out the Ben Heck's (2 pot version) and tried the one listed in the FAQ for the Atari Jr. That didn't change anything. It still looks exactly the same.

     

    As far as PAL or NTSC, I live in Tennessee, but I bought the Atari online. I can't remember where the seller was exactly, but he was state-side. I would assume the system is from the US also but who really knows. He claims the system was working perfectly, but then again, he didn't send me anything to connect it to a TV. I wonder if he even tested it.

  9. Posted · Edited by Bluebass

    I just noticed you mentioned a "mod", are you trying to build a portable? If so, both of your problems could be explained by construction mistakes.

     

    Turning the color adjust pot may not be able to give a B&W picture in every unit, but the Color/B&W switch should do so when using an early Atari-made game (just about any title with a text label should work for a test).

     

    No, the mod I did was Ben Heck's composite output mod. Just to make things simpler I'll put all the symptoms in one place:

     

    1. trigger buttons don't work from either port. Tried two sticks w/ same results.

    2. B&W picture is none existant. I flip the switch to B&W and the screen turns completely black.

    3. While in color mode, the colors are really messed up. I can get blue red green and black. I have yet to seen any lighter colors, i.e. white, or lighter variations of blue or green. Color is affected by the pot, but is never even close to the correct colors.

     

    I've never worked on a Atari, and I'm quite the novice when it comes to electronics. I've fiddled around with it as a hobby. I am sure I had the mod hooked up correctly, though. I believe I may have discharged a capacitor on the right side of the board opposite the RF circuit. about midway between the top and bottom of the board. I'm not sure though. I didn't smell any ozone, and nothing is visibly fried.

     

    P.S. as I understand it, you can't chop the atari Jr into the 4 inch square to do the portable version. At least, I think that's what Ben wrote. right or wrong??

  13. Posted

    Check the output of the 7805 voltage regulator. If it's low, it may be affecting the video quality and the controller ports. Both fire input needs to be pulled to 5v to be "off" and if it's floating lower than that due to weak voltage regulator, bad pullup resistor, shorted caps, or bad 4050 buffer (if used).

     

     

    7805 is putting out 5.06V. Is it possible that I discharged a capacitor somewhere, and something else went on it? I accidentally brushed the board and heard a pop. I didn't smell any ozone, and I couldn't visually see any fried parts.

  14. Posted

    I'm not sure why, but I can't get the colors to adjust right with the Ben Heck. AND the trigger button isn't working for either port. I'm looking for a schematic so I can test it. I had never even seen the inside of a 2600 until last night.

  15. Posted

    Does anyone have a schematic of the Atari Jr. I'm trying to figure out what is wrong with my atari Jr. I just bought it on EBay with no RF switch, so I wasn't able to check it before the mod. Now, the trigger doesn't work from either control port.

     

     

    Also, I can't seem to get the color adjusted right.

  16. Posted

    Does anyone here know how the S-video conversion was done? There was a website that sold conversion kits, but apparently they have quit offering them so you have to buy their upgraded systems. I read a review where the s-video conversion was supposedly more clear than some of the other methods of connecting to a TV.

     

    If I can't do s-video, I'll do the composite output conversion... unless someone knows a better way :?

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