Artifacts on old Famicom. Any chance to fix something like this?

[Rogerwilco]

I have a Famicom that was dead. I replaced the fuse and now it turns on, and I'm using the RF on channel 95

I only have one Chinese knockout game to test, I doubt is the game the one that is bad, but ill get another one just in case during the next days.

I cleaned the famicom cartridge slot pins with isopropyl alcohol
Also cleaned the game with isopropyl alcohol

this is what I get  (the square little thing is.... captain America.  

Can anyone tell me what can I do in these case? can it be fixed?, where should I start?
Is it possible it gets fixed by doing the AV Mod?





this is the board it has




thanks

[HVC-Man]

The PPU chip, PPU RAM or related latch logic chip could be bad.

[Rogerwilco]

thanks

Ram is U1 and U4
PPU is U5
but which is the  latch logic chip ?

then I think its going to be difficult, unless the famiCLONES contain the same chips as the original famicom. And with that I guess I can make a transplant. Original famicom is very rare around here. But I have seen Famiclones everywhere, same design and even different colors

[80sFREAK]

Reflow slot first and clean it with 600 grit sandpaper. Actually it is good to reflow whole board before you start replacing chips. Just do it with Pb6/3Sn37 soldering wire.

[Rogerwilco]

thank you 80sfreak, i will start with your advise.

do you know a lot about electronics? what kind of component is the one in the picture below yellow circle?
and what is the purpose of such component?? if that is broken coult it be the issue? i don´t even know the name for that


Post Merge: November 05, 2015, 09:40:52 am
ok so i started to look more closely to the board trying to find any problem or blown thing,  and i found something.

does anyone know what this broken thing is? and if it could cause the video glitches?




any help is greatl appreciated,  what kind of electronic component is that ? so i could buy a replacement.

[famifan]

does anyone know what this broken thing is? and if it could cause the video glitches?

definitely not. It's RF modulator. it's truly analogue by nature.

these artifacts are coming from digital parts. I second that it could be caused by slot connectivity or PPU, related SRAM, latches.

I only have one Chinese knockout game to test, I doubt is the game the one that is bad, but ill get another one just in case during the next days.

i think that could be an issue. Have you tried original (non bootleg) game for famicom?

i think that latches incompatible with modern CMOS/TTL ICs. http://www.famicomworld.com/forum/index.php?topic=9770.0

[Rogerwilco]

awesome!

thank you very much for your support, i can only say that it is working now, the problem was that brand new 10in1 cartdrige, somehow it is not compatible with my original Japanese famicom system.

I had to go to an old shop to get another famicom game, not original japanese because those are expensive here, somewhat a collector area
. but i got one that is a copy and that is very very old, like it has been used for years

I also did the the 600 sandpaper thing to clean it a littlebit

So the other old game runs perfectly,  THE ONLY BROKEN THING NOW IS THE RESET BUTTON, IT DOESNT RESET.

today this beauty was saved!... and i will do the AV mod in a few days

[80sFREAK]

A bit late reply to PM. About problems with modern carts, somewhere here was solution provided by our Polish friends

[Rogerwilco]

hi 80sfreak, i think you mean the solution below?

So far i found this diagram that seems to fix the problem but my chips are different



i got two : 29F800BA-70






i think the chip and schematics can be seen on this datasheet
http://www.datasheetcatalog.com/datasheets_pdf/M/B/M/2/MBM29F800BA-70PFTN.shtml

So on the PDF the OE is pin#14 at the bottom of the chip, and i need to lift it, and bridge it to pin#17 CHR

im i right?

What about the chip on the left? something needs to be changed there too?

[Rogerwilco]

ok i did this fix and the new china pirate is working correctly now
Just an FYI they might be ussing diffrent kind of chips inside, you will need to search which pins is OE, lift it up, then bridge the pin with #17 on slot

i cant belive these china pirate games the menu shows MARIO 9, and its a hack of adventure island, with mario head.

[famifan]

glad to know that it could be fixed.

sometimes they use glob top chips, giving no chance to find #OE pin.