(Topic ID: 182401)

GQ-4X 27c4001 troubles

By altan

7 years ago



Topic Stats

  • 9 posts
  • 6 Pinsiders participating
  • Latest reply 7 years ago by altan
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    #1 7 years ago

    Anyone had success using the gq-4x for m27c4001 chips?

    After verifying they are erased, I see

    1) failure to write (some byte didn't write)
    2) burns and verified but doesn't boot
    3) works fine

    So it's very inconsistent

    Anyone changed the speed setting to help?

    These are -10 chips.

    Thanks!

    #2 7 years ago

    Are you connected to an AC power adapter, or are you just using the USB cable?

    #3 7 years ago

    I sometimes lower the speed setting when having problems. It helps every now and then.

    I've had pretty good luck posting on MCU's forum when I have issues. It sometimes takes a few days to get an answer.
    http://www.mcumall.com/forum/forum.asp?FORUM_ID=9

    #4 7 years ago

    Check the VPP pin during burning if you are concerned about programming current dropping the voltage down.

    I have switched from using a 9v (DC!) wall adapter to a USB hub with a 1amp 5v power supply as I needed some other powered usb ports. Working fine even on 25v chips.

    ERPOMs can be fickle. Sometimes you just get a bad batch. Maybe someone in the past programmed your 12v chips at 21v and they are now damaged

    #5 7 years ago
    Quoted from ForceFlow:

    Are you connected to an AC power adapter, or are you just using the USB cable?

    Using USB. I thought about trying an external power supply, but I (of course) only have 5v, 7.5v and 12v ones!

    @stangbat, barakandl thanks for the suggestions

    Quoted from barakandl:

    ...
    ERPOMs can be fickle. Sometimes you just get a bad batch. Maybe someone in the past programmed your 12v chips at 21v and they are now damaged

    In this case, it's original WPC chips with their original factory stickers (that I've removed).

    As it turns out, I tried again this morning (using speed = 0) and it worked fine. Will see how it goes on future attempts...

    #6 7 years ago

    Never had any issues burning 27C4001. I have never needed the wall wart for them. I would try slowing the speed down.

    #7 7 years ago

    Do you guys typically leave the "Double Write" box checked when burning eproms? Couldn't find much info on this setting.

    #8 7 years ago

    To be honest, I leave it at the default, which I believe is unchecked.

    I believe double write is just that, the programmer writes the code twice to ensure all bits are burned. From what I have read, an EPROM can lose its programing over time, even with the erase window covered. Double write I imagine will last longer. I think you can burn as many times as you want as long as it is the same code.

    #9 7 years ago

    Quick update. I Have successfully burnt 2 roms tonight with speed at 0.

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