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 Post subject: Dreamcast black screen (drawing too little power?)
PostPosted: Sun May 02, 2021 7:25 am 



Joined: 08 May 2019
Posts: 17
I've been beating my head against the wall with my Dreamcast for a while now, trying to figure out why it's video is going black about 5-8 seconds after powering on.

1: Recently I did a USB-GDROM replacement, and that seems to be working fine.
2: I also did a Noctua fan swap, and wired it myself instead of buying a pre-made kit. I used an NF-A4x10 5v, and just matched the wires up with the pinout on the fan for the Dreamcast.

When my system started going to a blank screen shortly after boot, I assumed it was the PSU. I recapped it after seeing some of the caps were leaking, but the problem is still there.

So.. and here's the crazy bit; If I solder in the old dreamcast fan again, the system works fine. Re-solder the Noctua back in, and it's blank-screening again. Put the stock fan back in, and it's fine.

I've double and triple checked my wiring, and I'm sure I've got it right. The Noctua fan spins up and all.

Noctua: Yellow = RPM Speed Signal, Black = Ground, Red = 5V
Dreamcast: Orange = RPM Speed Signal, Blue = Ground, Red = 5V

What do you think this is? Is the Noctua fan not drawing enough power, and somehow causing an issue? I'd like to hear your thoughts.

Noctua Fan: 5V, 0.25W, 0.05A
Stock Fan: 5V, 0.7W, 0.2A


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 Post subject: Re: Dreamcast black screen (drawing too little power?)
PostPosted: Sun May 02, 2021 9:03 am 


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Joined: 09 Aug 2017
Posts: 1512
Location: Australia
Try a 10k resistor between red and yellow on the fan for load.


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 Post subject: Re: Dreamcast black screen (drawing too little power?)
PostPosted: Sun May 02, 2021 3:32 pm 



Joined: 08 May 2019
Posts: 17
Syntax wrote:
Try a 10k resistor between red and yellow on the fan for load.


That did the trick, thank you!


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