Proper voltage regulator replacement for NES

The voltage regulator on the NES system reads 17805, whereas other common systems have a 7805 regulator, like the SNES or Genesis.

I'm wondering a few things:
a) Are they interchangeable or the same regulator? In short, is the 17805 regulator replaceable with a 7805?

I've actually already replaced the NES voltage regulator with a 7805, and it did work for about 10 minutes then conked out. I'm not sure if I have a bad batch of Voltage Regulators, because I replaced a fuzzy Genesis with the same 7805 regulators (bought off eBay) and it seemed to work great for about 15 minutes, but now I'm getting no power on the Genesis as well.

I don't know how much the type of current (AC or DC) may effect the type of regulator used, I realize that the NES is DC in, whereas almost all other systems are DC out. Any tips, maybe just to know I'm doing something wrong or not is very much appreciated.

 

It's just a normal 7805, nothing special.

 

As the previous poster said. Nevertheless, if you want to have something special, you may use a voltage regulator which does not need any cooling attached to it. In example I use these two here in my NES' and SNES':

- http://www.digikey.com/product-search/en?x=18&y=10&lang=en&site=us&keywords=945-1610-5-ND
- http://www.digikey.com/product-search/en?KeyWords=811-2196-5-ND&WT.z_header=search_go

 

It seems rather pointless to replace a 50 cent voltage regulator, for which there's already a heatsink, with a $10 component.

The NES PSU is AC, not DC! Are you not using a proper NES PSU?

If you've replaced the regulator and it still doesn't work, either you did it wrong (did you use thermal paste to adhere it to the heatsink?) or there's another fault.

 

The NES can be powered by AC or DC, the console converts the AC internally anyway.

 

Check - the AC is converted with four diodes to DC internally. After that, there is the large 2200uF cap, power switch and the 7805.

I just said "if he want to have something special". Of course it is rather pointless, if you use original components. Personally, I removed everything including the heatsink and replaced the whole silver box with an own solution with AC/DC with diodes, DC/DC and video out. On my PCB there is also a MultiAV output to have it similar with the SNES

 

Since the OP is in Toronto, he presumably has a NTSC NES, which uses a DC supply - it's just the PAL ones that used AC.

Why, I have no idea.

 

NTSC ones used AC also. They all have a rectifier circuit inside to convert the AC to DC. DC supply would pass right through, regardless of center pin polarity on the adapter. The only problem with this is, you need at least a 9V AC or DC supply. 2 diodes in the rectifier will drop the input voltage ~1.4V and the 7805 needs at least 7V on the input pin to output a regulated 5V.

 

Yeah, I was having a dumb moment and was thinking of the SNES rather than the NES.

 

So to get back to an old thread, I just replaced the 7805 with a dud SNES system voltage reg. And, come to think of it, no I did not add thermal paste.. damn shame since I threw it out after that. Good tip to know, I will dig up my Arctic Silver on the next repair.

I stand corrected on the NES PSU being AC.. that is true, just a little mindfart on my part.

 

The Vreg in my famicom gets soo hot it will burn you :/ I'm using a pal MEga drive psU..
Should I replace the psu or Vreg with a switching one

 

What are some symptoms of a poor voltage regulator? I'm trying to figure out why I'm getting a gray screen of death. It's not the connector or dirty games. The RF capacitor looks fine. I'm running out of ideas. Every game except Mario/Duck Hunt gives me the gray screen and M/DH has some serious video problems. Half the screen is normal.

 

Wrong voltage output

 

Be careful changing the 7805 in a NES. If you short anything for even a split second it will kill your main CPU chip. Found this out the hard way since NOTHING is fused in that bastard and the main CPU is the most fragile of all. Resistance inside should measure ~240 ohms across the power rails. and for the love of god, add a fuse when working on this thing.

I have a custom SMD 7805 in mine now connected to a giant copper heatsink. The stock one indeed does get DAMN hot. Just another case of #NINTENDONT

 

Only reason a powered off system would kill anything on a short is if there is power left in the caps.

Unplug the system and turn the power on, then it's safe to work on.

Snes is exactly the same, the caps store enough power for the led to come on and also to blow the fuse if you work on it without discharging the caps.

 

The NES holds a lot of voltage in the 2200 16ufv cap for the 7805 input. It doesn't have proper bleed off resistors so it holds it there for minutes. Pressing the power button while off does nothing to alleviate this, since the LED and power switch run of the +5v rail. The SNES (and 90s consoles in general) does not hold 15v on power off like this.

And there is no fuse in the nes +5v rail.

 

If the cap is on the input, drawing power from via the 7805 is exactly how to drain it.

I've worked on many snes and nes, removing the cpus etc. Putting the power on works just fine. Same as anyone else who has installed nesrgb kits etc.

If you are drawing power from the 7805 and it's getting it's power from the cap...... Where exactly do you think the power on the 5v rail is coming from?

If I hadn't just sold my last 2 nes consoles, I'd have hooked up the scope and shown you.

 

yeah, I that makes sense. I think my issue came from powering it up without the 7805 installed because I was replacing it at the time and doing a bunch of mod work on it. It stored all the voltage in that cap and caused me some probs because there wasn't an easy way to discharge it.

 

Yeah that sounds like exactly what's happened.

Power input -> bridge rectifier -> large input cap -> 7805 -> power switch -> rest of the hardware

If you have the 7805 removed, the cap will get charged if you plug the power in (or didnt discharge the console before removing the 7805).