famicom blew 20 years ago(FIXED)

[Ribap]

Hello,

I'm completly new to the famicom world, this is my story with it:  My famicom blew 20 years ago and has been in storage since then as i bought a european NES right after, now after all this time  i would like to fix it.
My famicom was bought 22 years ago in Japan, and brought to Europe, i think it is one of those weird PAL famicoms, it is PAL because i was able to play with it in Europe without any mods, just as it came from japan.
I remember that when it blew, some smoke came out of it and some burnt smell, i have read that this problem usually is because of using Nes AC adapters with the famicom. I have been reading lots of post about this and  it seems that i could fix it changing the 7805 regulator or the fuse. I dont think the 7805 reg is the problem as it looks ok, but, there is some dirt around some capacitors, it looks as the problem is there, but i dont really know as i dont know anything about electronics. My motherboard is quite rare, i have not seen any like mine in here, it doesnt even have a number, that makes me think that maybe i have a famiclon...but the rest looks legit, who knows...anyway, i leave some pics, so maybe you could help me find the problem:


upload picture

this is the motherboard, as you can see, is quite rare:


picture hosting

Thanks.

[133MHz]

It is indeed a clone. Replace the 7805 and the electrolytic capacitors around it, they're dirt cheap so don't skimp on that.

If you want to know if it's NTSC or PAL, check the value on the crystal oscillator (the component that looks like a skinny tin can). 21.xxx for NTSC and 26.xxx for PAL (the part number on the main chips start with P so it's very likely that it is indeed a PAL machine).

[80sFREAK]

Dead parts usually looks ok from outside.
Japan=NTSC-J, so no PAL equipment here.
Do you have 1)multimeter 2)soldering iron 3)basic knowleges?

P.S. LOOK! WOW! RARE!

[jpx72]

P.S. LOOK! WOW! RARE!

I like the word "KONAMI" on the board (the first picture)

Your famiclone has two crystals, that's weird None of my PAL famiclones of this type has two crystals. Also, none of my famiclones has a fuse 

[manuel]

P.S. LOOK! WOW! RARE!

Last time I checked it's L@@K! 

[Ribap]

Thanks for the help.

I checked both crystal oscillators and one of them has 21.xxx and the other is 26.xxx as you can see in the pictures:


upload pictures

So in order to repair it i am going to replace the 7805, the three capacitors around it, and that black fuse close to the small capacitor (although i'm not sure it is a fuse, is it??).
Before trying to replace anything i'm going to check with a multimeter the fuse and the 7805.

So it is a famiclone 100%, both controllers have turbo buttons, the motherboard even has the KONAMI logo on the back.

I will update my progress.

Thanks.

[jpx72]

I checked both crystal oscillators and one of them has 21.xxx and the other is 26.xxx as you can see in the pictures:

Heh from what I see your famiclone might be first universal PAL+NTSC clone I've ever seen! Congrats!

[Ribap]

Well, i have checked the fuse and the 7805 and they are ok, the 7805 has an input of 14.8 more or less and the output is 4.8 more or less, so that means that it works, does it?
Is any way to check the capacitors?

Regards.

[ericj]

You can check the caps output for + voltage, just ground the other lead of your DMM.

However, I'd first check for voltage at the cart connector. If you don't find it there, you can either work your way forward from the 7805 or backward from the cart connector to find the source of the problem.

[Ribap]

The caps output have voltage, also both pin 30 an 31 from the cart connector have voltage, although only 1,30 more or less. What else could i check?. It may be that the famicom is not sending any signal to the tv??

[jpx72]

only 1,30 more or less.

On cart connector should be the same value as on the 7805 output. So in your case 4,8V

[80sFREAK]

Can you measure voltage between pin20 and pin40 of CPU?

[Ribap]

only 1,30 more or less.

On cart connector should be the same value as on the 7805 output. So in your case 4,8V

I have a doubt with this, should pin 30 alone give a 4.8V? or the sum of pin 30 and pin 31 voltages should be 4,8V?

Can you measure voltage between pin20 and pin40 of CPU?

do you mean check the voltage in pin20 and then in pin40 and see the difference?

Thanks for the replies.

[jpx72]

only 1,30 more or less.

On cart connector should be the same value as on the 7805 output. So in your case 4,8V

I have a doubt with this, should pin 30 alone give a 4.8V? or the sum of pin 30 and pin 31 voltages should be 4,8V?

Pin 30 should have +5V, also pin 31 should.  Pin 01 is GND. Check the pinout:
http://wiki.nesdev.com/w/index.php/Cartridge_connector

Can you measure voltage between pin20 and pin40 of CPU?

do you mean check the voltage in pin20 and then in pin40 and see the difference?

Thanks for the replies.

Pin 40 of the CPU is +5V, pin 20 is GND.  He want's to know if the CPU is getting the proper power supply.

[80sFREAK]

jpx72 is exactly correct - it's good to know, if PCB wasn't damaged and all chips powered correctly. Same about slot - crack the cart(non glob-top), plug it in proper, measure voltage on chips.