Installed GDemu on dreamcast but not working

Discussion in 'Modding and Hacking - Consoles and Electronics' started by namrood, Dec 5, 2018.

  1. namrood

    namrood Active Member

    Aug 15, 2016
    Likes Received:
    Hi everyone

    Other half bought a GDEmu 5.5 (2018-04-25) for my birthday but now has been the only time I have been able to start this project due to having limb manipulation on my shoulder and I'm off work. But I am having some issues. I have copied over the files to make it work and setup some games in the directories (01, 02 etc)
    But when I turn iy on the GDEmu it flashes once and nothing else happens (no display etc)
    My dreamcast is PAL/UK and the case has the 1 in a circle and on the board it says 'Katana' so I'm sure it is a VA1

    What I am I doing wrong before I scrap it and buy a new dreamcast with a working drive.
  2. linglang

    linglang Rising Member

    Oct 21, 2014
    Likes Received:
    Did you buy one from Deunan (the original creator), or a Chinese clone on which you can not update the firmware ?

    If it is a Chinese clone, you are on your own, but you could try these "solutions".

    There is a status LED on the GDEMU, it should blink once during power-up and then remain off.
    If the LED is lit, or starts blinking during gameplay, an internal error has occurred.
    There are many possible causes of that, including SD card data transfer errors.
    The only way to restart correct operation of the device is to power-cycle the entire console.
    If the problem persists try a different card brand/size.

    In what format did you copy the games to the folders, .cdi, .gdi ?

    Are these the correct dumps, from the correct release groups ?

    "IMPORTANT: Recently some new dumping groups have been releasing GDIs dumped with PC CD-ROM drive using so-called “swap method”.
    Technically there is nothing wrong with it except for slightly different “offset” on audio tracks compared to what Dreamcast drive would produce, nothing you’d even notice.
    But they’ve changed the way track starting address is calculated and as a result all games that have digital audio, or data split beyond track #3, will not work properly.
    This is not a GDEMU issuse and there is no fix planned for this – avoid such dumps."

    You use the original BIOS ?

    No other modifications ?

    Even an original GDEMU is very picky about memory cards, it has to do with random access times.

    Try another brand / type of memory card, FAT32 formatted.

    I had audio sync issues with some type / brands of cards, on an original GDEMU.

    In what file system did you format your memory card, FAT32 ?

    What is the capacity / brand of the (genuine) memory card ?

    As Deunan himself says:

    I’ve been getting more and more emails from people who bought and tested 64GB+ cards.
    It occured to me that rather than having to retype this every time I should just make a public post.

    Yes, I know SDXC cards work. If formatted to FAT32 that is, preferably with SD Formatter.
    However, GDEMU was not designed with that in mind and while it seems to work for most people, for some it just might not.
    I cannot test every brand and model of SD cards, and there are some that don’t behave nicely (like the Transcend Class 10’s) and there’s nothing I can do about it.
    I don’t want people buying expensive high-capacity cards only to learn they don’t work well, or at all.
    Therefore the official support ends with 32GB SDHC cards and it’ll stay that way.
    If you feel lucky and want to try something bigger, you’re on your own.

    Obviously for bigger cards the current limit of 64 folders is too low.
    I’m going to skip the usual rant on design choices I’ve made – you want the limit to be 99+, you can get it.
    For a price. Right now GDEMU does a prescan of the card folders and can gracefully skip holes in numbering.
    With more folders both the prescan and the storage of results get too costly, so will have to go.
    Scanning on keypress would introduce too much lag with many folders, so basically it would become a dumb “try N+1,
    wrap back to 1 if it doesn’t exist”.

    USB support, long filenames, breakfast making – not coming in foreseeable future. Don’t bug me about it.

    Did you place GDMENU in the first folder ?

    No strange long names and characters in the file names ?
    Helper app for easy converting GDI dumps with long names to 8.3 format.

    Power supply problem ?

    Known issue – all Dreamcast's suffer from a poor connection between the power supply (PSU) board and the mainboard.
    This is typically caused by oxidation of the metal pins on the mainboard and gets worse with age but most of the time can be easily fixed, see below.

    "But when I turn iy on the GDEmu it flashes once and nothing else happens (no display etc)"

    No video signal at all ???

    GDEMU has undervoltage detector that will cause it to reset itself and blink the status LED if the 3.3V line drops below 3V. This is on purpose, most SD cards will not work properly with unstable power supply and this issue cannot be easily detected otherwise.
    Typical effects include:

    • random game hangs (note: these can also be caused by SD card itself)
    • random resets/reboots
    • sound “too slow” and/or wrong pitch, or missing completly
    • GDEMU status LED blinking randomly
    NOTE: Sometimes the original drive will appear to work in a given console but GDEMU won't.
    This is because neither the drive nor the mainboard have any sort of undervoltage protection – however this configuration will not be stable and will eventually also start randomly resetting itself and even fail to boot at all .

    The fix is simple and can be done by anyone capable of installing GDEMU:

    • disconnect all cables from the console
    • unscrew and remove the upper part of the case
    • unscrew and remove PSU board (there is also a plastic latch holding it in place)
    • wipe the metal contact pins sticking out of the mainboard well with a clean cloth
    • assemble everything back and test
    Small amounts of alcohol on the cloth can help remove any contamination, however do not use any aggresive solvents or acids, or sand paper instead of cloth. The issue can be made worse if improper repair is attempted and the spring contacts in the PSU are bent, or the pins are treated with abrasive material and the anti-oxidation layer is completly scraped off.

    Worst case scenario the PSU or mainboard might need to be replaced. Alternatively the pins and PSU connector can be desoldered and replaced with wires – it’s not as easy but will permanently fix the problem (provieded the PSU is not faulty to begin with). Note that attempting to solder the pins and the connector contacts together usually ruins both while not actually providing a good connection (the solder tends to break off after a while).

    Do not put stress on the solder connections on the mainboard, do not break it !

    Does it say 3,3 V on the original GD Drive ?

    Anyhow I hope for you this helps, and happy birthday !!
    Nully likes this.

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