Search results

  1. channelmaniac

    MV1FS question (UPDATE - actually no sound!)

    Look into getting a small spool of 30ga Kynar wire for doing the patches. Easy Peasy.
  2. channelmaniac

    MV1FS question (UPDATE - actually no sound!)

    Hey, I know that asshole in that video! :) (Me!) If you get the beeping and scratchy sounds then you have digital data making it to the DAC. You either have a bad DAC (unlikely) or a bad cap (VERY likely) in the audio section. RJ
  3. channelmaniac

    MV4 top board issues, only slot 1 works

    Nice fix! If you look closely you'll see that there are 4 repeating rows of chips on that top board. They are all connected together on the Neo side of things with the other side if the chips going to the slots. The 74LS138 in the bottom corner is used to select which slot. The 74LS244 chips...
  4. channelmaniac

    Revolution x wont boot up need a board repair

    I've fixed a couple of these boards... They suffer from 2 common ailments: 1) Spills corroding things as the board is mounted in a bad place in the cabinet... and 2) the capacitors leak and the electrolyte eats traces. I absolutely hate working on them as desoldering leaking caps stinks the...
  5. channelmaniac

    MV1FZNB2 Garbage Screen/Green Screen Loop

    Click of death is most likely a RAM failure - Work RAM or Backup RAM... or a failure on the control lines to the Backup RAM. See if you have signals on /CE and /CS. It's normal for one to be tied to ground... but the other should not be stuck low. If both are low then you'll have those RAMs...
  6. channelmaniac

    Sound Issues on MV1-FT

    It's not going to be the Z80. You have sound sample ROMs on the top cartridge board (the one with the Program ROMs on it.) One of the address lines isn't connected to those Sound Sample ROMs properly. If you were getting just scratchy sounds, I'd say check for a missing data line... Incorrect...
  7. channelmaniac

    STV Cartridge instructions and trouble shooting

    Folks, ST-V systems aren't the best designed systems... the PCB flexes too much and operators generally didn't put mounting feet on all the mounting points to keep it stable. When you buy one the first thing you do is run the self tests. The second is to run the factory tests. Test mode: Power...
  8. channelmaniac

    Fixed! - Was: Need a ROM file to repair a Super Contra...

    Edited the post to add a few more things I forgot that were replaced. There was a bad SRAM, rotted pin Sound ROM, and corroded program ROM sockets. I was able to clean the pins and save the Program ROMs, but the Sound rom left multiple pins behind when I removed it from its socket. Another...
  9. channelmaniac

    Fixed! - Was: Need a ROM file to repair a Super Contra...

    Got the 27C400 EPROM from China - real Intel chips too... Super Contra is fixed. That last EPROM would properly checksum but not work at speed in the circuit. Replacing it finished the repair. :) So that repair consisted of 2 dead Fujitsu 74LS74 and sockets, 3 dead and 1 chattering Fujitsu...
  10. channelmaniac

    Mystic warriors pcb arent showing sprites.

    Reflow the chips around the one you pressed on. You flexed the board when pressing.
  11. channelmaniac

    Moonwalker with white stripes.

    Or a bad RAM. Not all show up on self tests.
  12. channelmaniac

    MVS 2 Slot No Sound

    On the 2 slot boards... if Backup RAM gets corrupted it can do that odd thing where you hear the beep in test mode but no audio from games. Reset the Backup RAM and try again. Next, if you have bad continuity between the slots and the NEO-G0 or NEO-257 chips over by the sound CPU then you won't...
  13. channelmaniac

    MVS 4 Slot Repair Help

    Oh, and try flipping all the DIPs on. Sometimes when you have stuck enable lines or bad Backup / Work RAM, it will help the error messages to pop up. It starts a diagnostic routine on the standard BIOS.
  14. channelmaniac

    MVS 4 Slot Repair Help

    A few things come to mind... Bad Backup or Work RAM can cause this. Battery leak damage? If so, check the traces around the 74HC32 for continuity. If you have stuck low conditions on the Backup RAM you'll end up with data bus collisions. Sometimes the 74ALS245 chips on the data lines going to...
  15. channelmaniac

    Mystic warriors pcb arent showing sprites.

    The couple that came across my bench both had bad solder joints on the SMT customs causing the graphics issues.
  16. channelmaniac

    Power Up Baseball Conversion

    Bump... Built one tonight... wasn't too bad at all. I had a crusted up corroded MK3 with plenty of 27C080 EPROMs on it so I figured why not? I picked up the GT2K board as scrap for parts in a trade. Worked first try. Only hiccup was having one SMT 0-ohm resistor go flying, but I have a drawe...
  17. channelmaniac

    Fixed! - Was: Need a ROM file to repair a Super Contra...

    Down to 1 ROM error... and it's a ROM image in the last mask ROM... but I ran out of those oddball pinout EPROMs in the parts drawers. Have to go dig in boxes now to find more.
  18. channelmaniac

    Fixed! - Was: Need a ROM file to repair a Super Contra...

    OK!!! Pin 87 of the 051961 custom was dead. That's the NIRQ signal to the CPU that gets buffered by a 74LS367. The CPU was waiting for the interrupt to be returned and it never arrived... Watchdog reset hit the CPU. Replaced the custom and it's working... BUT... There are graphics problems with...
  19. channelmaniac

    Simpson board

    Last I saw, Delilah was hoarding them.
  20. channelmaniac

    Fixed! - Was: Need a ROM file to repair a Super Contra...

    OK... Yet another Fujitsu LS153... This one had chattering outputs. Also a dead trace to pin 22 of the hybrid. Now I have the proper color text and the crosshatch showing up before it reboots.