Mega Drive 1 - No video or sound, LED does NOT come on

Discussion in 'Repair, Restoration, Conservation and Preservation' started by Shaitan, Apr 3, 2014.

  1. Shaitan

    Shaitan Member

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    Hi everyone!

    I have a Mega Drive 1 that, when turned on, displays a flash on the screen, followed by a black screen. I hear no sound and no humming coming from the console. Also, the LED does not come on.

    I am using an original AC adapter and AV cable. The board seems to be OK, with no visibly blown fuses (EDIT: I meant caps) and the cart slot has been thoroughly cleaned.

    What else should I look for?

    Thanks in advance for your help.
     
    Last edited: Apr 8, 2014
  2. dc16

    dc16 Dauntless Member

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    You might need to break out a multimeter and start checking.
     
  3. Shaitan

    Shaitan Member

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    Thanks for you input, but I have no idea how, where or what for... :/

    Would you be so kind as to elucidate me?

    Thank you very much.
     
  4. retro

    retro Resigned from mod duty 15 March 2018

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    Basic troubleshooting. I'd suggest getting some beginner's electronics books first and having a read - you'll learn a lot.

    If the LED isn't coming on, you're basically checking power at various points first (PSU, LED, chips....)
     
  5. Shaitan

    Shaitan Member

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    Well, now the LED does power on. It was torn apart from the board when I received it, so I may have connected it wrong and now that i've de-soldered it and connected it again, it does come on.

    The rest of the console remains the same. Please note that after the screen flash, there is image being transmited but it's completelly black.

    Tomorrow I'll get a new battery for my multimeter and try to check somethings. I think I've learned how to check the voltage regulators, so that will be the first thing.

    Again, thanks for your input.
     
    Last edited: Apr 9, 2014
  6. Nully

    Nully Dauntless Member

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    I'm having the same issue with a model 2. I thought it may be the video chip so I went as far as cleaning the solder points with alcohol, touching it up with new solder, desoldering it and soldering it back in. It didn't help so I would advise against blaming that I suppose. I don't have an AV cable so I'm just using RF but it works with 2 other model 2s. I also cleaned out the cartridge slot. I'll tell you if I figure it out, but I'm stumped for now.
     
  7. Shaitan

    Shaitan Member

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    OK. Voltage regulator output is 4,92v. Compared to 5v, I don't know if that's enough... I have a working Model 1 whose volt regulators output 4,98v.

    Nully, I really hope the problem is not on any of the chips... :/
     
  8. retro

    retro Resigned from mod duty 15 March 2018

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    Don't just probe the regulator, check other sections of the circuit, e.g. chips for power as a start.
     
  9. Shaitan

    Shaitan Member

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    I tried to research how to check the rest of the circutry with a multimeter, but the only info I could retain was "Do NOT screw up, or you'll short circuit something!" As such, I am very weary of doing it... :/
     
  10. Lastcallhall

    Lastcallhall Rapidly Rising Member

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    First, check the power regulators at the heat sink. You should have roughly 10-13v coming in, and ~5v coming out. If those are good then you know your power jack is good.
    Next, flip the board upside down and check the AV pinout. Here's a diagram: http://atariage.com/forums/uploads/monthly_06_2011/post-29207-0-78876700-1306894337.jpg You should get 1-3v from everything except 5v and ground. If all those check out, take the heatsink off and check the video encoder (CXA1145). Here's the datasheet: http://console5.com/wiki/CXA1145. You should get some sort of voltage from everything except 1 and 24. Beyond that, you're looking at measuring caps and resistors individually. If there's an actual SEGA logo flashing, then it would seem something is shorting it out, but if it's just a flash, that's just an indicator that there's power going to the board, and something else is at play.
     
  11. dc16

    dc16 Dauntless Member

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    Most problems with Segas are the capacitors. Buy a capacitor kit and two 7805 voltage regulators from Console5.com.
     
    Last edited: May 2, 2014
  12. compil3r

    compil3r Active Member

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    I agree that it should be a capacitor problem. I've read that almost all of our beloved consoles from that time should start to give capacitor problems today due the time that has passed.
     
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