Famicom stopped working - Recommendations?

I purchased an original Famicom from japan (ebay) two weeks ago.
Today I received the package and connected it to my tube tv.
As I currently live in europe and original power brick is AC100v input, I plugged it in with my Super Nintendo power brick which has similar specs (9-9.4v output) but it didnt work.
I decided to use my Sega Genesis 1 power brick, which has the same output as the original one (10v)
The console worked fine, as I was testing several cartridges, until after 5-10 min I turned it off, changed game and turned on, to get a black screen. Then the previously tested (working) games also gave me the black screen.

The tv seems to react when I turn the power on, the black screen moves a bit.

I don't know if i messed it up when i connected the SNES power brick, as the plug might be different than the original one... But in this case, shouldn't it have stopped working right away?

Anyway, if you have any suggestions on how to proceed into this please enlighten me.

By the way, this Famicom has an AV mod.

I'm at work right now, so I can't check my notes, but IIRC the PAL SNES power plug is 5.5 OD x 2.5 ID. The Famicom and model 1 Genesis are both 5.5 OD x 2.1 OD. So the PAL SNES power plug would have just been a loose fit, but shouldn't have damaged anything.

My guess would be dirty cart slot and dirty carts, which can cause it to sporadically work and not work. I suggest cleaning the cart slot and the cart contacts really well.

The pal snes power brick outputs AC, this is bad(tm).

A famicom requires DC. But also the plug is center negative. I'm suprised it even worked after you tried the snes power plug.

edit: Forgot to give more advice. Things you can check: check if you're getting 5V out of the 7805 regulator, the pinout can be found on google. If not, replace it.

Thanks for the answers guys!

About the cleanup - yeah, I thought about it. It's really hard to clean the famicom connector and games. I purchased the famicom and several games just recently and who knows if they ever were cleaned. Tomorrow I will give them a deep cleaning and try again... But with my experience on the NES carts/connectors, by watching the output at the screen ... this smells like something else.

About the SNES power brick: Jeez. I did it all during work hours so it was all in a rush. Didn't check enough but i was 100% sure that the SNES power brick outputted dc.

Well, tomorrow I will do the cleaning and buy some tools to test voltages. Im 10k km away from home and have nothing with me. Also I'm a software guy, do not know much about hardware. So support is very appreciated.

I think, in case I blowed it up with the AC, is there chances I blowed something that I can't replace?

doubt it. i just bought a famicom with disk drive on ebay that the seller did the same thing. all it needed was a new 7805.

If I remember correctly, the Famicom has a 1.5A picofuse that is often the source of this type of problem. I've seen it blown a few times when people bring theirs to me for repair; use a cheap multimeter in to check for continuity. It's the same fuse as in a SNES and they're easy to find online.

Okay, I got a multimeter and tested the thing. First I did a good cleanup of the cart slot and still didn't work.

Now, as I've checked some videos on the internet and seen the famicom board, I noticed that the circuit for the power management is different than the ones I've seen, so I think this might have been replaced. Here's some pictures of it:


original size: https://i.imgur.com/vuiZT2o.jpg


original size: https://i.imgur.com/muNdXwd.jpg


https://i.imgur.com/wTlA73A.jpg


original size: https://i.imgur.com/U1s7DH8.jpg


original size: https://i.imgur.com/W8KVMa6.jpg

I don't seem to find the fuse around the whole board. Any ideas where that could be here? I might not be seeing it.

Now, I tested the 7805. Plugged in my sega mega drive power brick and tested the output. It is around 12 volts.


original size: https://i.imgur.com/hKeCYiP.jpg

Excuse me for my ignorance, but I also tested the power brick and the output is around 13 volts. Is this normal? Pictures of the tests:


original size: https://i.imgur.com/USm4hjZ.jpg


original size: https://i.imgur.com/hCdLI3D.jpg

In the case this is a replacement circuit without a fuse, (excuse me again for my ignorance) is there a possibility that I have fried other parts of the circuit with the AC? and with 12 volts?

I will go ahead and try replacing the 7805 next week I guess.

There is no fuse on the famicom, only super famicom.

Are you sure you're measuring the output of the 7805? If it's outputting 12V it's very likely other parts of the circuit are damaged. But I think you might be measuring the input.

As far as the power brick outputting 13V, this is normal, power bricks based on transformers tend to not be very exact, and also will vary depending on the load.

Some Famicom revisions absolutely have a 1.5A picofuse but not in your motherboard revision (yours is an older one, and the daughterboard is original), so there's one less thing to check. The best way to troubleshoot is to follow where the flow of power should be from component to component, and figure out where it stops. If everything seems okay, your problem is elsewhere.

check the pads labeled VCC and GND on the bottom of the main PCB for 5vdc, I wouldn't rule out that shoddily done "av mod" either. do you get audio at least?

Well, I'm actually measuring the output pin and it's indeed ~12v. The input pin measures ~13v.
It's good to know that the boards are original. Hope I can repair them.

I thought about the av mod but with the broken regulator its probably not the case. I never got any audio output after the "incident".

I ordered some new 7805s and going to give it a try when they arrive. Let's cross fingers that it's only that.

Well, I replaced the regulator. It's outputting ~5v, but still not working. The tube tv reacts every time I turn on the famicom, but the screen moves a bit only.

This is looking a bit bad to me

Thanks for all the help so far.
I will spend some hours this weeked trying to learn how to debug the circuit and see if I can find out something broken.
If you have any more ideas that can be helpful to me, I appreaciate that.

I want to check if the AV mod is working well first I guess. But no sound/image at all.

Try to look if there's any voltage on the mainboard's ICs.
Maybe there's some power circuit problems, or you have some fried ICs.

The most obvious test you could try to see if one of the ICs is fried should be the temperature test.
Just touch it and see how hot it is. If it's too hot it's probably fried.
But this test is just useless if there's no current arriving at the mainboard.
You can also try to do the diode test on the IC's terminals as described here.

To do a better test you could find another Famicom/NES/Famiclone, socket its ICs and test the suspicious component on it.
Hope you can fix it!

@OP, I did the same thing!
I recently got a Famicom console, and I knew not to use a NES power supply as it is AC.
For whatever reason I believed the SNES PSU to be DC, Maybe there's a Euro vs USA vs Japan difference?
So after doing an AV mod I plugged in the bare board to the SNES PSU.
After 2 seconds a cap (1000uf) near the power inlet popped and let out a puff of smoke.
I will be replacing that first, testing further, and obviously using a more suitable PSU.

*EDIT* I have replaced the one cap, plugged in a Sega PSU and it's fine!
Good luck with yours.

Thanks a lot for the recommendations. I'll start today after work

About USA SNES, PAL SNES and SF PSUs, I think there might be AC/DC differences for different regions actually. I bought this PAL SNES in Germany a few months ago, but all my life I've used USA consoles exclusively. My original consoles are back home and don't have them to check atm, but so far I have seen some pics of SNES PSU from different regions and seems that the NTSC (USA/Japan) output DC and the PAL ones output AC. Jeez.

I will try to upload a complete report of the debugging soon.

Great!
Keep us informed and good luck!

Alright, I did some testing and noticed a few things:

When I tested the Famicom turned off, plugged to the PSU:

- The power sub-board seems to work correctly, I followed the power flow up until the on-off switch and it was all ~5v.
- Just in case I checked if there was any voltage in the mainboard, but there wasn't.
- I checked the connection between the power sub-board to the main board and found the VCC cable:



There I saw the VCC marked cable, and in the back of the board I saw that the two cables to the (right in the photo) of the one marking VCC are connected.
None was delivering any current to the main board.

For now everything seemed to be okay. I turned on the switch and tested again, to see:

- The 7805 is now outputting what seems to be exactly 3V. Not sure if this is the normal behavior.
- Now the mother board is powered with the same charge of 3V, by the three cables mentioned before.

This may be okay, I left it turned on a few minutes and started touching the ICs. I touched them with the skin just above my nails which is a bit sensible. What I noticed is that some ICs heat a bit, some more than others, and some don't really heat:



Here I marked the ICs with dots to find them easier.

- The blue dotted ones (TC40H368P) don't heat at all.
- Also both ones next to the purple dotted ones (SN74LS139N and HD74LS373P) doesn't seem to heat at all.
- The green dotted one (RP2A03E) and the one above it (RP2C02E-0) heat up a bit. Let's say they get warm.
- The purple dotted ones which are both TMM2115BP-15 start heating up. If I leave my finger on it, it burns a bit after some seconds.

My knowledge on these motherboards is pretty much null, so I don't really know what is each IC.
How much heat should they produce?

Then things got interesting:

After maybe 3-4-5 minutes I started smelling a bit of heated up plastic. And smelling around, I found out that it came from the power sub-board.
- Then, I realized that the whole metal cover had an intense heat, that would burn my fingers if I touched it.
- I turned it off and unplugged everything.
- I plugged the PSU and turned on the famicom again after everything cooled down (10~ mins).
- I noticed that the 7805 was heating up really fast, heating the small heat sink and the whole metal cover that's in the power board.

I don't have how to measure temperature, but it was really hot, much more than the ICs. Not sure if this is normal though.
I didn't want to leave it turned on much more.

Do you think that the ICs are fried? In that case, it's pretty much not worth it to find substitutes?

@Addam: Does your FC have a fuse somewhere?

The 2 ICs that heated a lot may be defective. Try the diode test on them.
Also, it's not normal the 7805 outputting 3v neither heating that much.

The burnt smell makes pretty sure there's a short circuit somewhere and possibly are these ICs.
They are the RAM of the console, the one that is connected to the 74LS373 being the CHR RAM, the other is the PRG RAM.

Try to find what's causing the sort circuit before powering up again, if you need to test, watch the 5v output to see if the short is gone or more damage can be made.

Good luck!

The CMOS RAMs (e.g. the TMM2115) tend to be some of the most easily damaged parts in a NES/Famicom. I wouldn't be surprised if that's why it's broken now.

A 7805 will emit less than 5V if one of two things happens:
- Too much current is drawn (which is also consistent with the RAM being damaged)
- Too little voltage is supplied (which you've already verified is not true)

@FIsher: So I've done the diode test, using the thread you suggested to me.

I used the image in this post for the names of the pins:
https://forums.nesdev.com/viewtopic.php ... st#p201653
Even if some chips have slight different names and numbers I used the pin names found there.

In the lower 2k x 8 SRAM I found:
- A10 pin - infinity
- all other pins show different values

In the upper 2k x 8 SRAM I did'nt get infinity on any pin.

In the PPU
- On Pins 14, 15, 16 and 17 when I test, the values move a bit and drop to zero. Seeing the image one of these pins is GND.
- No pin has infinity.

In the CPU:
- /IRQ pin has infinity
- CLK has infinity

In the 74LS139 there's no pin with infinity.

The 74LS373P guy has no pin with infinity either.

The I measured the two toshiba TC40H368P at the bottom on my motherboard. For this i used the datasheet:
https://www.datasheets360.com/pdf/7486811487654332985

In the one on the left (on the last image i posted of the mother):
- 6A, 4A, 2A, 1A = inifity

In the one on the right (on the last image i posted of the mother):
- 6A, 5A, 4A, 3A, 2A = infinity

Well, I have done this test twice both on saturday and sunday, to confirm the measures.
I guess I have a few doomed chips and they are probably the cause of the short circuit.

You can try to remove the suspicious chips and see if the sort circuit persists by watching the tension at the +5v line.
Try to test it quickly or you can have the bad smell again and something more can be damaged.

To do these kind of tests I used to unsolder the +5v and/or gnd, but I was told that's not a good practice so I recommend you to remove the suspicious chip entirely.

Good luck and happy father's day!:-)
Please, keep us informed of your progress.

Haha I see you are from Brasil! happy father's day to you too

I desoldered the CPU and quickly measured the 7805 output. The outputted voltage measured around 3,7 volts.

I was desoldering the ram and my unsoldering unit started working bad. I will try to fix it and go on tomorrow.
Will keep posting the results.
Thanks again

No fuse, I just replaced the 1000uf cap and found a suitable PSU.
I was lucky, the damaged component was easy to find.
You might need to do a little more diagnostics. Do you have a multimeter?

Yes, I borrowed a multimeter from a friend.
I followed what Fisher told me to test, so I made diode testing on all the IC's.
I found that removing the CPU made voltage increase a bit, but it seems there's still a short circuit. I started de-soldering the suspicious ram chip but the desoldering unit was heating the chip way too much.

All in all I ended up buying a famicom top-loader, but I still want to fix the original famicom. Right now I believe chances are that I blowed a few IC's. And I guess that fixing this would involve buying several junk famicoms and make some sort of frankenstein unit. I doubt it is a capacitor (or only a capacitor) at this point

I will go back at desoldering tonight.

I would be tempted to cut my losses and just buy another cheap famicom like this:
https://www.ebay.co.uk/itm/Untested-As-is-For-Parts-or-repair-NES-Console-Famicom-NINTENDO-FC-AU-Oa8/192592628934?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649