Jump to content


  • Content Count

  • Joined

  • Last visited

Community Reputation

518 Excellent

1 Follower

About ChildOfCv

  • Rank

Recent Profile Visitors

4,282 profile views
  1. BTW, some armors in the game cast rever when used as an item. They can also be used outside of battle. Some armors cast gires, but only in battle.
  2. Okay, updated the program to change its messages for the bad cartridge tests. Also, if you only had the single video test, you now have one for NTSC and one for PAL. The NTSC one should also now have good timings, so no more weird tearing. As usual, plug into Windows, find out which COM port it is, and run diag_flash COMx where x is the port number. diag_flash.zip
  3. I suppose a microcontroller could be used to perform this. You'd have one output pin with a 1K resistor. It connects to an input pin and to the paddle input. Finally, it has a sensor from the digital pot. Operation would be: Output goes high. When Atari resets to get paddle position, this brings its trigger input low and it turns off the output. Output waits for a period of time according to digital pot, then turns back on. This allows it to respond to the Atari's paddle dumper. But instead of a sawtooth rise like you'd normally see with paddles, it just sits low until trigger time and then suddenly charges up.
  4. Who said you're not supposed to socket the chips? You do have to be careful since they used thin traces, but I have not heard of adverse affects from socketing. Did the seller you bought that top board from say anything about doing repairs? Maybe you could send your old top board in to have it fixed.
  5. Even worse, the Anti magic has a percentage chance of working rather than being a sure cure. You have to adjust your technique strengths to decide which one is most important (and mostly important).
  6. It is the same as on the Adam. The mistake is that Texas Instruments labels the bits backwards on many of the 99xx series. Look closely at the bus connections to pins 17-24
  7. Look closely at the connector. Are the pins deformed? Are they multi-colored due to oxidation? Do you have a cartridge without the case that you can test continuity with?
  8. Just some followup on this since I am partially building another board at the moment. The connectors are Molex(R) and gold-plated, so it probably isn't a connector problem. The ribbon cables were hard to find, and I finally got a batch from somewhere (can't remember if Amazon or eBay). Anyway, I would easily blame them for the problems. https://www.mouser.com/datasheet/2/276/1/0878340611_PCB_HEADERS-152817.pdf
  9. That's bad news. I wonder if it's the ribbon cable connectors or that the pins might be too skinny for spec. Well, one alternative might be to use dupont connectors. They'll definitely fit those pins and sockets. Just make sure to match up pin 1 etc
  10. I did some analysis of leakage current for chips that are on the bus but not sending. Resistance of a transistor is, of course, not constant. But I used datasheet values to estimate a resistance range to see what they all end up doing together. Input ICs: 135K each SRAM: 400K (there are two, of course, but they are divided between the data lines so a single data line only considers one of them) CPU: 500K ROM: 240K VDP: 52.5K (yikes) Parallel resistance: Around 23.5K. So that does put up a decent fight with the 10K resistors. Perhaps they should be reduced to 2K. If you have the solder skills and confidence, try replacing R12-R15 and R22-R25 with 2K resistors.
  11. Also, note that the text stated that if one of the select lines (x000) are implicated, then you should look at U5. I guess it mentioned them while activating them specifically, but the only thing implicated in those tests was the shield line. I guess that's to be expected though when you've removed the RF shielding, and therefore it has no conductivity to ground. Maybe I should make a note about that too. Hmmm, I just realized that it's the lower half of the shield that's supposed to connect the cartridge shield ground. So removing the upper part wouldn't be a problem. If someone removed both halves though, you have a problem and need to solder a wire from the shield connection to ground. I'll also make an attempt to adjust the code so that it doesn't print the troublesome message unless one of the select lines failed to activate.
  12. Some of that could be the connection to the system. I noticed similar problems while developing due to residue of flux getting on everything. Before connecting to the expansion port, clean it as well as you can. You may even want to go over the card edge contacts on the diag board to make sure they remain uncontaminated. Contact cleaner may help, but make sure it has no alcohol or other conductive stuff in it or else you have to clean it up after use too. DeoxIT cleaners claim to have no alcohol and claim to be nonconductive. But anyway, if it can't make a good connection, it's not driving the system. It's only making suggestions. To answer the question about what the stuck pins test does, it uses a 10K resistor to pull the pins in question high, then tests if there is anything fighting against that. Then it repeats the test while pulling everything low. It could be that 10K isn't aggressive enough, but it seems to me that if no chip is attempting to drive the bus, it ought to be enough. However, it is possible that some chips are "leaky" but not enough to keep the system from failing outright. Generally if one chip is only sorta shut down, another chip that wants to drive the bus can do so, but at the cost of increased power. I've wavered between whether or not to use a smaller resistance to do the tests with, or to say that maybe there is a chip that's on the verge of failing, or is at least not within spec, and it really should be tracked down and replaced. On the other hand, it's a game console. What do you expect? Still, since Zak's system seems to have a bad VDP, it's possible that it is the culprit in the stuck pins too.
  13. Yeah the Atari version has different timing delays between outputs, as opposed to all the standard ones with constant delays.
  • Create New...