Powering NES with a ATX PC power supply and no 7805 IC

[wyatt8740]

Would it be safe to remove the 7805 IC (because it can only safely regulate power with at least 7 volts) and power my NES directly with an old IBM power supply that outputs 5 volts at 14 amps? I know that the 7805 brings it down to 5VDC and I am pretty sure a PC PSU is well regulated.

If you need to know why I want to do this, it is because I have a problem with my everdrive N8, and I want to check if the FPGA on it is simply not receiving enough power. I don't have any wallwarts that provide a decent number of amps to test this theory.

[Super-Hampster]

I don't see why not. I've done it before with a small power supply out of an external hard drive enclosure and it worked fine.

[wyatt8740]

So you did remove the 7805 and connect it in it's place, right?

To clarify: I'm not talking about running through a barrel connector. I mean directly into the NES, bypassing it's internal protections.

[lidnariq]

PC power supplies often have a minimum load requirement on the +5V and/or +12V lines, and if there isn't that minimum load regulation isn't guaranteed. Make sure you don't run into that problem. Otherwise I think it should work.

[ApolloBoy]

If you need to know why I want to do this, it is because I have a problem with my everdrive N8, and I want to check if the FPGA on it is simply not receiving enough power.

14 A is overkill for the NES, why not just use a model 1 Sega Genesis power supply?

[Memblers]

So what's the rating of your usual power supply? I always use a 600mA rated one, and have never had a problem.

Other than the previously posted warnings, to be safe I'd run it through a fast blow fuse (maybe 1.5A or 2A?). Not strictly needed, but at 14A I'm thinking a fault would blow the traces right off the board.

From what I understand, ATX also supplies standby power at 5V. So you'd have to use one of the pins on the connector with a switch (or just short it) and also draw some minimum amount of current, but the standby current will always be there. I don't know what the threshold is, but if the NES was near it, I'd guess that could be bad.

[tepples]

PC power supplies often have a minimum load requirement on the +5V and/or +12V lines, and if there isn't that minimum load regulation isn't guaranteed.

Then how do they work if the machine goes to Suspend state?

[lidnariq]

Suspend doesn't draw power from the front +12V and +5V lines, only from +5VSB. Otherwise they couldn't achieve the very low standby power consumption necessary for Energy Star approval when on standby.

(Power supplies have a specific amount of power at which they operate at maximum efficiency, and anything above or below that is less efficient. A 400W supply that's providing 2W could well consume 10W or more.)

[MottZilla]

If you need to know why I want to do this, it is because I have a problem with my everdrive N8, and I want to check if the FPGA on it is simply not receiving enough power.

14 A is overkill for the NES, why not just use a model 1 Sega Genesis power supply?

The Genesis Model 1 (and I think Sega CD too) power supply provides 1.2amps of power. More than enough for the NES and some cartridge that may be drawing more power than usual. It would be a better way to test your theory since you'd just plug in a different power supply.

[wyatt8740]

If you need to know why I want to do this, it is because I have a problem with my everdrive N8, and I want to check if the FPGA on it is simply not receiving enough power.

14 A is overkill for the NES, why not just use a model 1 Sega Genesis power supply?

If you need to know why I want to do this, it is because I have a problem with my everdrive N8, and I want to check if the FPGA on it is simply not receiving enough power.

14 A is overkill for the NES, why not just use a model 1 Sega Genesis power supply?

The Genesis Model 1 (and I think Sega CD too) power supply provides 1.2amps of power. More than enough for the NES and some cartridge that may be drawing more power than usual. It would be a better way to test your theory since you'd just plug in a different power supply.

I don't have a genesis.
=[

I'm still 17 and my parents won't let me bring home more consoles to take apart until I throw something out, which is sacriledge.

And I thought that the NES AC adapters were rated at 1.3 amps? Isn't that more than the genesis? or does it have to do with the conversion of AC->DC why the genesis one would be better?

Also, a list of consoles I DO have, in case one has a viable alternative to the ATX PSU:
Three NES systems (one a broken top loader), a SNES, an atari 2600, a commodore 64 with a homemade PSU (it runs on 9VAC from a NES transformer), a VIC-20 with the original power supply brick, and a tandy 1400 laptop's internal power supply.

[Super-Hampster]

So you did remove the 7805 and connect it in it's place, right?

To clarify: I'm not talking about running through a barrel connector. I mean directly into the NES, bypassing it's internal protections.

I didn't remove anything. I soldered it right on to the 5v input.

[ApolloBoy]

I don't have a genesis.
=[

I'm still 17 and my parents won't let me bring home more consoles to take apart until I throw something out, which is sacriledge.
.

Nobody said you had to get a Genesis...

[MottZilla]

Right, you just need the power brick for one. You don't need the console.

If you are using an original NES power brick, it does output 1.3amps. If that isn't enough then I bet something else is the problem.

I use as 3rd party AC adapter that outputs 9VAC at 1.3amps and use the PowerPAK with no problems. I don't have an EverDrive though. I would think it couldn't use that much more power but maybe it does.

[tokumaru]

Both my PowerPak and my Everdrive work fine with the original NES power supply. I'm sure Bunnyboy and Krikzz would have a lot of trouble if they didn't. That being said, there could be something wrong with your power adapter in particular, but confirming that with a PC PSU might be overkill.

[Pokun]

My Famicom + Everdrive works perfectly with my 1A AC-DC adapter I use with my Famicom even. You could try a new NES AC adapter first.