Hello, I recently purchased Final Fantasy for the Nes, and when I took it apart to clean it, I noticed one of the diodes was broken. I have no idea what type of diode it is. I know it is a diode form the symbol on the circuit board. There is another diode just like it on the other side of the board. I took the battery out to replace it. I attached some pictures so you can see what it looks like. Thank You for all the help you can give.
hi,
It could be an ordinary diode or a zener.
Can you use a ohm meter to measure the 'other' diode thats located further along the PCB, it has the same markings as the broken one.
You will have to de-solder one end of the diode to measure it.
Can you also post the colour code from the 'good' diode.??
It looks orange with Yellow paint on the end near the cathode, and a silver line down the middle. It looks the same as the good diode. I get 0.563 when I test it. There are only 2 total, and they are labeled D1, and D2. Thank You for the help.
Thanks again for all the help. how can I find out the specs that I need to go and buy one. There are no markings on it. Can I test the good one, to find out what I need?
it looks like a reversed polarity protection diode from the battery...try to check if the broken one is connected in series or parallel of the battery line...1N4148 i think will do the job..
The NES cartridges that had battery backed RAM used diodes so only the RAM was powered when it was switched off. I would just try a 1n4148 and see if it retains the memory. If it doesn't then it may require a schottky diode but I think that is unlikely.
Thanks for all the help. I am no electronics expert, but I think the broken one is parallel to the battery line. I should have mentioned that the game does not work at all. All I get when I turn on the NES is a black screen. I thought once I replaced the diode the game would work. If that diode only has to do with the battery, then something else is causing the game not to work. Everything else on the board looks fine. I can post more pictures if you want a better look.
It looks to me as if the battery has leaked acid all over the board. Clean it with a paste of bicarbonate of soda and a little water. Then clean that off thoroughly with distilled water and then dry thoroughly with a hair dryer on low heat. After that exam all track with a magnifying glass. Replace any that are damaged.