I have an older (non-clone) Famicom system that I don't know if it is powering up or not. I have a Super Famicom system that works just fine with the same rf/power supply on channel 95/96 so I know that's not the problem. I would like to know if anyone knows of another way to test to see if the system is powering up such as adding a led as the system does not have one. Any input on this would be greatly appreciated. Thanks.
Just attach the LED's anode to +5v through a 220-1k ohm resistor and the cathode to ground anywhere on the Famicom.
For some reason I'm thinking the FC only takes DC, while SNES/SFC/NES can take AC or DC. I could be remembering totally wrong though, since I've never had an FC. If it can't take AC or got fried from wrong polarity you could try replacing the regulator (7805) in there.
You could also use a voltmeter between VCC/GND in there and see if it's got voltage when it's switched on.
I'm not quite sure about the DC, I think it uses the same as the super famicom as shown
here.
That is the one I am using. I could be wrong though. I will try out these suggestions. Thanks for the responses. If anyone has anything else, please let me know. Thanks.
link length fixed - admin
Memblers wrote:
For some reason I'm thinking the FC only takes DC, while SNES/SFC/NES can take AC or DC.
Yes, the FC is DC only, tip negative.
(10v DC, 850mA to be exact - a Genesis AC adapter model 1602-1 works nicely)
Famicom really takes anything over 7v (DC); if you use a 7V supply instead a "10V" supply (which generally are really 12-14V or more) your regulator will be running 4-5W cooler!
SFC/NTSC SNES only runs on DC too (no rectifier, but it does have a protection diode which the Famicom does not have stuffed.)
NES/PAL SNES has a rectifier so it can take AC or DC.
Speaking of LEDs...
The camera doesn't even capture how intense and rich blue the new LED shows up as, but it's pretty nice.
My question is though, is there a resistor on down the line somewhere? One would think there would be, to keep from burning out the red one, but based on how bright the new one shows up, despite it being an ultrabright version, I thought I better ask before I take a chance on burning it out.
So that I don't screw up the system if it isn't already, does anyone know exactly where to install the led on the famicom? Thanks for all the help guys. I have my older Mega Drive AC adapter SA-106A (Output DC9V 1.2A) I will give that a try too although my old adapter was DC10V 850mA. Anyhow, any help on where to install that led so I don't screw up putting it in the wrong place would be great. Thanks.
A system that accepts AC is much more resistant to being fried, because it can almost always accept DC of either polarity, and almost always will have a voltage regulator after the rectifier, allowing a wide voltage range. A system that accepts DC needs the right polarity or things could get damaged. They usually have a voltage regulator as well, since it allows using a cheaper unregulated wall transformer.
For a long time I used a modified SNES power supply for my NES. I had added an extra plug that fit the NES, so I could have just one power supply that worked for the NES, SNES, and even Sega Genesis (but powering more than one at once didn't work well, heh). Recetly when I was testing a PAL NES, this DC power supply didn't work well at all. There was an awful hum. I tried several other DC power supplies but none worked. Once I gave in and used a proper AC power supply, the hum was gone.
FyberOptic wrote:
The camera doesn't even capture how intense and rich blue the new LED shows up as, but it's pretty nice.
The problem with those blue power LEDs is that they are very distracting, which isn't a good feature for an entertainment box that sits near the TV. Like good user-interfaces, the goal is to avoid drawing attention away from things that matter.
silkd wrote:
I have my older Mega Drive AC adapter SA-106A (Output DC9V 1.2A) I will give that a try too although my old adapter was DC10V 850mA.
I also used to use my Sega Genesis power supply with my NES, as I remember.
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Anyhow, any help on where to install that led so I don't screw up putting it in the wrong place would be great. Thanks.
With the series resistor connected to the LED, connecting it wrong won't screw anything up permanently. Pretty much if you experiment connecting it in various ways around the power switch, once it appears to work right it'll be working right.
blargg wrote:
The problem with those blue power LEDs is that they are very distracting, which isn't a good feature for an entertainment box that sits near the TV. Like good user-interfaces, the goal is to avoid drawing attention away from things that matter.
lol it's true, it lights up the room enough with the lights out to see where you're going. My PC has a similarly bright blue in the ring around the power button. But neither sit in a position to be of distraction when in use, luckily. And in the case of the NES, I could probably slip the LED back out of the plastic light channel thing and point it straight up, which would lessen the intensity a lot I'd bet.
Anyhoo, I didn't realize it at the time, but I guess it was pretty rude to hijack the topic with my own mostly unrelated question. Sorry about that, silkd!
blargg wrote:
For a long time I used a modified SNES power supply for my NES. I had added an extra plug that fit the NES, so I could have just one power supply that worked for the NES, SNES, and even Sega Genesis (but powering more than one at once didn't work well, heh).
I have the same power adaptator for my NES and SNES, as well as the same AV output, and I didn't modify anything here. I just think american users got different power adaptators, wile european users got the same.
Yes, PAL SNES take AC over a normal power jack like the NES, U/C SNES use a proprietary connector.
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So that I don't screw up the system if it isn't already, does anyone know exactly where to install the led on the famicom? Thanks for all the help guys. I have my older Mega Drive AC adapter SA-106A (Output DC9V 1.2A) I will give that a try too although my old adapter was DC10V 850mA. Anyhow, any help on where to install that led so I don't screw up putting it in the wrong place would be great. Thanks.
Hey silkd, the second post, the one by Calpis explains how to install the led. Super simple...just 4 soldering points.
-Rob
Put the led on, didn't seem to work. I need to get another battery for my multimeter and I will test the system to see if it's powering up. I saw the pinout for the cart port somewhere around here. If it still doesn't power up, I will put a new switch in to test that...after that any sugguestions? Possible to replace the power supply in the famicom itself? Thanks for all the responses guys.
Switch is probably OK, though I imagine you could test that with the multimeter.
I would test the power at the voltage regulator (7805, 3-pin thing connected to a heatsink of some sort). First pin (near the dot) is the input voltage, that should read as what the DC input is from the power adapter. Middle pin is GND, 3rd pin is output voltage which should be around 5V. If you get different results, put in a new 7805. As far as the power supply, if the previous owner mis-used it the 7805 would be the first (and only?) thing to go. Also check for damaged/exploded capacitors near the regulator.
I will keep you updated on how this goes. I have to run to the store and get a new battery for my multimeter. Thank you again for your help.
Just an update: I tested the 7805 voltage regulator and got nothing on the input or the output. If it was damaged, would I get anything at all on the input? Either way, I am going to try and replace it tomorrow. If anyone has any other ideas/suggestion I'm all ears. Thanks once again for everyone's help.
If you've got nothing on the input with respect to ground (as I remember, the pins are Vin, GND, +5V out), then power isn't getting to the regulator in the first place. Have you verified that the power adaptor works at all? If so, then see if it's getting to the power jack and trace that to the regulator.
The power adaptor is working properly, I have tested that. As far as testing from the power jack, any advice? Thanks.
Sorry if this is a dumb suggestion, but be sure the meter is set to measure DC voltage and not AC voltage. AC mode is usually depicted with something like a wavy line.
To check the power jack I'd just look and see if it's looks like it's soldered properly, hasn't came loose or something. That's probably the most likely point of failure.
Although unlikely, maybe the regulator blew? Are you getting power before the regulator? Because if the adaptor is defeinitely working, and there's no power to the regulator, something inbetween those two, or the regulator is fucked up.
-Rob
Yes, it is set to DCV. After testing more, the best I can tell with limit knowledge is that I am not getting anything before the regulator. I tested at what I think is the power jack (very small area, not able to see from the top, tested on bottom of board) and it didn't even register 1 volt. I know the multimeter is working just fine. Any suggestions now? Replace power jack? Let me know guys and thanks for the input.
If the power supply is working, then you MUST have something on the input. Are you sure you're measuring right? Just in case, it's black probe to middle pin, red probe to left/right.
Power supply is working. I confirmed the multimeter is working properly by testing it on other devices, batteries, etc. I am getting a .22v on the input of the regulator and 0 on the output (testing middle/ground and the input and output of the voltage regulator) Still not sure what's going on. Is it possible to connect a different power supply direct to the votage regulator to test if the system will power up? Can another power source connect direct the input of the regulator?
You're not trying to use a NES power supply are you? One reason for the .22V may be because it's not a DC supply! Put the meter in AC mode and see if that makes a difference. Also are you sure you have the thing on the correct range setting?
If it is a DC supply, measure the voltage with your meter. You can directly attach a regulator to the supply but depending on the regulator and supply, the ripple may be too much for the Famicom. (You may need the capacitors.)
Yeah, it's a DC supply. putting in AC didn't do show anything. I'm really thinking about wiring a battery supply to the famicom similar to what they did in many portable nes projects just to deliver power to the regulator to get the 5v to power the system. I will give that a shot tomorrow. If anyone else has anything, give me a shout. Thanks guys.
If your power supply works, there's no need to wire a battery, your supply is directly connected to the regulator. The only last thing I can think of is a center polarity positive supply. What type of supply are you using?
This makes no sense. If the adapter is definitely working, then you should have straight power before the regulator. Unless the board is actually cracked right there. WTF?
-Rob
Adapter is definitly working (tested with S. Fami) I was playing with it a bit more today and right out of the power supply I am getting about 22.1v I get that up until a (fuse?) labeled 50c 1.5a on fuse itself and 1.5a ssfr right next to it written on the mainboard. other side I am not getting anything. If that is a fuse, i'm guessing it's bad....am I on the right track? Thanks.
Sounds like an open fuse, and of course whatever caused it to open in the first place. One possibility is that 22 volt power supply! That sounds a little on the high side, even for an unregulated 9V supply without any load.
After a bit of research on it, it is a 1.5a pico fuse. I need to just find a replacement for that....makes me wish I wouldn't have tossed a couple of old nes and snes non-working systems I had around a couple years back
Anyway, would I be able to use a different amp fuse? Would it be ok to use a 3 amp pico fuse? Thanks.
Me being a little on the ignorant side when it comes to electronics, is an open fuse just a bad fuse? That was 10v power supply I am using that is giving me 22v on the famicom. I just tried a 9v power supply I had and it gave me 14v.....what would be causing that?
Normal AC adapters are unregulated and run at higher voltages unless they have the load applied to them that they were designed for. A volt meter obviously doesn't supply much load, so you see way more than the rated value. The power gets regulated once inside the NES/Famicom to keep a constant voltage for the parts.
Regulated by the 7805 chip correct? It regulates it to the 5v needed by the componet?
Interesting. I didn't know about the Famicom, but I don't think there was a fuse in the NES. Yes, open is bad. It means the circuit is broke (disconnected). I don't know how that would've happened, but maybe it'd be worth a quick check that VCC and GND aren't shorted in there. A 3A fuse replacement should be OK. Or just a wire. As long as whatever fried it is gone.
22V does sound really high, must be really cheaply made or something. Should be OK still though. I have a 12V 1500mA supply from Radio Shack that measues ~14.6V with no load, sounds great by comparison.
I know the fuse is there for a reason, but would it be safe to test and rely on the regulator just for a few minutes?
A bigger than big thanks goes out to everyone that helped me out with this. I finally got it working!!!!
In the in, it was just that simple 1.5a picofuse which I have bypassed with just a wire for now. I plan on replacing that as soon as I can find one. A 3amp should work right guys? I just want to thank everyone again for all their time, guidance, and patience with helping me out with this. For my next stunt, I am going to try my hand at an AV mod, which shouldn't be too hard at all. Thank you everyone who helped me with this.
3A slow blowing fuse is not a really good idea since that won't protect the 1.0/1.5A regulator at all. In the case of a short, it also may be too late.
You should stop using that supply immediately BTW, (22V-5V)/.850A = 20W; I'd be surprised if the RF modulator chassis doesn't desolder itself :)
I will try to find a better power supply from the shack as soon as I can. As far as the fuse would a 1 amp fast acting fuse be a better choice? Again, I am very unfamilar with electronics and such, so please forgive me.
The original supply is only rated for 850mA so I think that will be fine for even top-heavy carts ;)