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Thread: Replacing a Sega Nomad's Voltage Regulator.

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    Great Puma (Level 12) jb143's Avatar
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    Default Replacing a Sega Nomad's Voltage Regulator.

    Does anyone happen to know the internal regulated voltage of a Nomad? I'm assuming it's 5V but I'm not sure. My Nomad had a fried regulator when I got it and I thought I made a work arround. But now I found it won't work on fresh batteries...only half dead ones...which usually isn't a problem with the Nomad but now I'd like to use an adapter for obvious reasons.

    I want to attemp to replace the regulator so any help will be appriciated. Extra points if anyone actually measures the voltages. I'll be sure to post my results here so others can make the same repairs. Thanks.
    Last edited by jb143; 04-25-2008 at 11:18 AM.

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    Pac-Man (Level 10) FABombjoy's Avatar
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    Probably 5v, but you might be able to determine it like so:

    1 - Locate the datasheet for another component
    2 - Verify continuity between VCC on that component and the output leg of regulator
    3 - Per datasheet, VCC for component is regulator output voltage

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    Strawberry (Level 2) SnowKitty's Avatar
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    Quote Originally Posted by jb143 View Post
    Does anyone happen to know the internal regulated voltage of a Nomad? I'm assuming it's 5V but I'm not sure. My Nomad had a fried regulator when I got it and I thought I made a work arround. But now I found it won't work on fresh batteries...only half dead ones...which usually isn't a problem with the Nomad but now I'd like to use an adapter for obvious reasons.

    I want to attemp to replace the regulator so any help will be appriciated. Extra points if anyone actually measures the voltages. I'll be sure to post my results here so others can make the same repairs. Thanks.
    i'm pretty damned sure it's +5V dc.
    meow :3

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    Great Puma (Level 12) jb143's Avatar
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    I'm almost positive too...I just havn't been able to cross reference the regulator. I jumpered the input voltage to the output of the regulator but any voltage that's too high it just won't work...and I disconnect for fear of burning something up.

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    Pac-Man (Level 10) FABombjoy's Avatar
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    Wait... you jumpered the regulator input to the output?

    uh...

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    Great Puma (Level 12) jb143's Avatar
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    Yes...to verify operation. It was completely dead before that. Don't worry...I didn't plug in an adaptor.

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    I'm still not too clear on what you were trying to accomplish, or where the fear of burning something up came from if it wasn't plugged in

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    Great Puma (Level 12) jb143's Avatar
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    Other than a very quick flach of the LED when you turn it on or off it was dead when I got it. There wasn't any noticible problems so I got out the ole logic probe and multimeter. Everything before the regulator had power...everything after, not so much. I powered the backlight seperatly and it worked so I knew no voltage was getting there. So then I just routed power arround the regulator and voila...as long as the batteries were just dead enough it worked great.

    As far as not wanting to burn anything else up. I really have no idea what happens to TTL or CMOS with overvoltage, or how long the smoke will stay in them. Why take my chances.

    I'm thinking that the previous owner plugged a reverse polarity or AC out adapter into it and fried the reg so they tossed it in the box o' game stuff that I bought from them.

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    Great Puma (Level 12) jb143's Avatar
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    I've verified 5V...now I just need to find a sutable replacement for the regulator. It seems to have a different pinout than most I've seen...although I'm pretty sure I could solder an LM7805 in there.

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    Great Puma (Level 12) jb143's Avatar
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    Default Regulator replacement instructions.

    I finally got around to replacing the regulator and it works great now. I've had several people ask me about this so I figured I'd post what I did. It was pretty simple to do and took me about 15 minutes to do. Please ask any questions becasue I'm sure some of this will need cleared up a bit.

    I could never find an exact replacement so I used part number MC78M05BDTRKG - 68cents from digikey.com. I mainly used this becasue it's what I had access to and it had a higher current rating than others. It's a "D-PAK" package so it's quite a bit bigger than the original regulator making it easier to work with but it's still an SMT part making is small enough to fit in there. I'm pretty sure any +5V linear regulator will work though.

    The first step was removing the old regulator. I used a hot air gun but I realise most peole won't have access to surface mount rework equipment so heating with a soldering iron and prying the chip off will probally work just as well. Then clean the pads up as much as possible making sure that there's no solder shorting them out.

    As far as clearance goes the only thing you need to worry about is the plastic circle on the other half on the Nomad. I had to relocate my regulator becasue I couldn't get it closed back up the first time.

    I then soldered a wire to each of the legs of the regulator. One was Vin the other is +5V out. These should be marked on your regulators datasheet. +5Vout n the board is the larger pad where the regulator used to be, so the other end of that wire should be soldered there. For Vin I soldered it to the point where +V comes off the power jack.

    To help dissapate heat I decided to solder the regulators ground tab right to the circuit boards ground plane. To do this I sanded away a small square of the boards coating near the edge of the board making sure the plastic circle I mentioned above would clear it. This left a square of exposed copper roughly the same size as the regulators ground tab. Be sure to clean off the dust made from sanding.

    Since the ground plane will dissapate heat, you'll probally need to hold your iron on the copper pad you just made for qute a while in order to heat it up. Once it's hot enough, add a layer of solder and then place the regulator down. Again, it's probally going to take a bit before the solder takes.

    If all goes well you should now once again be able to enjoy handheld Genesis goodness.

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    Strawberry (Level 2) phreak97's Avatar
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    if anyone has a nomad that doesnt work, ill pay $5 for it :P


    nice work on that repair.. though i wouldnt have put new batteries in it at all.. six aa batteries puts it at 7.2V with rechargables or even 9V with alkalines.. either way is a bit too toasty warm for 5v ICs.. the smoke is built in for a reason, it needs to stay in there.

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    Great Puma (Level 12) jb143's Avatar
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    Quote Originally Posted by phreak97 View Post
    nice work on that repair.. though i wouldnt have put new batteries in it at all..
    I never put in fresh batteries...I just tried some that weren't quite dead enough to get 5V at first...and once it wasn't working I turned off power immediatly.

    All is good now and I've testing with rechargeables and a power supply.

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    Great Puma (Level 12) jb143's Avatar
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    Default Regulator Diagram

    Here's a picture that might help anyone trying to make this repair.



    It's basically a surface mount version of a regular 7805 regulator that you can usually get at Radio Shack.(If you find room in the Nomad then you could probally use one of those)

    I'll try to add actual photo's of my repaired board this weekend to show where everything goes.

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    Strawberry (Level 2) phreak97's Avatar
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    ah ok, all good then

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    Cherry (Level 1) raylydiard's Avatar
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    Great Puma (Level 12) jb143's Avatar
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    Yup...that looks like the part I was looking for several months ago. Mine has been working fine and the repair has held up quite well.

    btw...the digikey part number for that part is LM1117MP-5.0CT-ND
    "Game programmers are generally lazy individuals. That's right. It's true. Don't let anyone tell you otherwise. Since the dawn of computer games, game programmers have looked for shortcuts to coolness." Kurt Arnlund - Game programmer for Activision, Accolade...

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    hi did you make a photo of your repaired board

    Quote Originally Posted by jb143 View Post
    Here's a picture that might help anyone trying to make this repair.



    It's basically a surface mount version of a regular 7805 regulator that you can usually get at Radio Shack.(If you find room in the Nomad then you could probally use one of those)

    I'll try to add actual photo's of my repaired board this weekend to show where everything goes.

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    Great Puma (Level 12) jb143's Avatar
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    Quote Originally Posted by raylydiard View Post
    hi did you make a photo of your repaired board
    Hmmm...I don't think ever did. It wasn't too pretty but it's worked fine for these past 2 years. If I would have been a bit more patient and found the exact regulator you mentioned above, I would have gone that route.

    If you're interested in seeing it though, I'll try to remember to snap a picture this weekend.
    "Game programmers are generally lazy individuals. That's right. It's true. Don't let anyone tell you otherwise. Since the dawn of computer games, game programmers have looked for shortcuts to coolness." Kurt Arnlund - Game programmer for Activision, Accolade...

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    thanks ?

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    Quote Originally Posted by jb143 View Post
    Hmmm...I don't think ever did. It wasn't too pretty but it's worked fine for these past 2 years. If I would have been a bit more patient and found the exact regulator you mentioned above, I would have gone that route.

    If you're interested in seeing it though, I'll try to remember to snap a picture this weekend.
    ---------------------------------------------------
    I'd much rather you send a photo as he did the procedure, so that you would help me a lot.

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