Sega nomads no power, inverted pos/neg on the battery pack

[Andrei123]

Sooo, I messed up two nomads trying to convert a battery pack using a sony cam battery. Unfortunately now I cant get either one of them to turn on, one of them gets a light on briefly. The other nothing.
Is there a fuse on this thing that I can replace ? I bought a broken nomad before and attempted a voltage regulator fix but that didn't fix my nomad, that one has the same issue light briefly comes on but that's it.

[Andrei123]

As an update:

Well I did a voltage regulator replace on both units, that got them working which made me reeeeeally happay.

Huge BUUUT here, the units work fine for a few minutes then they just go crazy system reboots and image goes dark and shaky, sound starts to slow down. I am not really sure what is happening, seems like the voltage regulator gets really really hot and this starts to happen.

[Hobie-wan]

Did you use the proper one? Maybe some of the caps got a little roasted too before something blew.

[Andrei123]

Did you use the proper one? Maybe some of the caps got a little roasted too before something blew.

I replaced the two power caps on the power input, it didn't do anything. Then I got stupid and replaced the purple cap in the back ... which I broke big time, I messed up the lead by mistake.

But the weird thing that happens is when I power it on it works, if I touch the vOut pad on the voltage regulator with my meter it stops stuttering and starts working properly. So I am thinking its something with the voltage regulator, I soldered it and desoldered it on a few times thinking that it doesn't have proper contact with the board. Also wondering if there is a resistor or something in between that is broken, or something to drop the voltage because I measure about 10+ volts on the input.

Any help is greatly appreciated.

[Andrei123]

Sorry, forgot to mention

I used a 5volt 800ma voltage regulator, its an LM117MPX, the ones ive seen in the videos were 5volt 1a. Im not sure how that would explain the system working fine for a few minutes. As in its 100% perfect, just seems like its heating up a lot faster and starts to screw up.

[Hobie-wan]

If the original was 1A, then the replacement needs to be as well.

[Andrei123]

If the original was 1A, then the replacement needs to be as well.

p

I actually don't know what the original was, I just saw a few guides around and bought the parts they suggest.

So heres what ive found, the one Sega power supply I was using was putting out 0.85A @ 10V the voltage regulator I had in there was rated at 0.8A. So that is what was messing it up. How I fixed is by using a lower power supply, I actually had a sega power supply ... not sure exactly for what but it does 0.3A @ 10V and the thing works perfectly now.

Out of the two nomads I broke I fixed one, sadly I think the other one is gone. Once I removed the purple cap in the front it stopped working. Board gets voltage and stays on perfectly just doesn't boot the game ... or maybe boots the game but doesn't display anything.

Wish I had a schematic for the thing.

[Andrei123]

I am happy as a pig in ..

I got both of them working now, the problem was a broken lead between the resistor and the cap I replaced (the purple cap).

Just in case someone else reads this thread. If youre going to do a voltage regulator job on the nomad, make sure you buy the 1A one. Most of the ones suggested around are of .5A .8A. If youre using a sega genesis power supply for your nomads it actually puts in 0.85A which is more then the voltage regulator. I left the 0.8A voltage regulator in there but switched to a 0.3A power supply. No issues anymore.

[Hobie-wan]

Using a .3 A power brick when the official one is .85 is not good. For power bricks,the voltage should match, the polarity should match, and the Amp output of the brick should be the same or higher than what the device needs. The device will only pull as much as it needs.

[Andrei123]

Using a .3 A power brick when the official one is .85 is not good. For power bricks,the voltage should match, the polarity should match, and the Amp output of the brick should be the same or higher than what the device needs. The device will only pull as much as it needs.

Well that's the thing, this is an official sega power supply. The one I was using before was for a sega gensis. Red online that the nomad runs on the genesis power supply so that's why I used it.
Back of the nomad says 3.5w at 9V so that is roughly about .38a so technically either of the voltage regulators should do fine.
It would be good to know what actual draw the system has while its running, also im guessing the draw changes based on volume and brightness. But either way it shouldn't be more then .4a

After fixing them I rigged up a battery pack with a 7.4v 2000mah battery and it works just fine also. Mind you im not an electrical person by any means, so I don't quite understand the difference between a power supply and a battery.