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reverendshoebox

Anyone here ever repair a Famicom?

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Hey guys.

 

I purchased a broken Famicom during a recent trip to Japan, and I've been trying to figure out what the heck's wrong with it. I get absolutely nothing when I turn it on - I'm using an Atari RF switch and I've tried the TV on channels 95 and 96, but no dice.

 

From my research so far, it sounds like the most likely things to go on these are the power switch, the fuse on the power/RF board or the 7805 regulator (also on the power/RF board.) My multimeter confirmed the power switch and fuse are fine - but how would I go about checking the regulator?

 

And if replacing that doesn't do the trick, what's next?

 

Thanks a lot,

-=ShoEboX=-

 

 

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So the system gets power (check chips for 5v) but no video at all, not even black screen or *anything*?

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Hey guys.

 

I purchased a broken Famicom during a recent trip to Japan, and I've been trying to figure out what the heck's wrong with it. I get absolutely nothing when I turn it on - I'm using an Atari RF switch and I've tried the TV on channels 95 and 96, but no dice.

 

From my research so far, it sounds like the most likely things to go on these are the power switch, the fuse on the power/RF board or the 7805 regulator (also on the power/RF board.) My multimeter confirmed the power switch and fuse are fine - but how would I go about checking the regulator?

 

And if replacing that doesn't do the trick, what's next?

 

Thanks a lot,

-=ShoEboX=-

 

 

 

 

I assume you've already figured out and resolved the whole 120 vs 220 and NTSC vs PAL thing?

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I assume you've already figured out and resolved the whole 120 vs 220 and NTSC vs PAL thing?

Actually Japan uses 200V and NTSC, so not an issue. :) I thought Japan was PAL too for some reason, but nnnnnope.

Edited by reverendshoebox

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So the system gets power (check chips for 5v) but no video at all, not even black screen or *anything*?

 

Haven't checked the chips for 5V yet. I'll do that. And no, no black screen.

 

And any idea how I verify a 7805 regulator is functional?

 

Thanks muchly for the response.

 

-='Box=-

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Power supply?

 

I've tried a SMS supply (9V 1A) and TurboGrafx power supply (10.5V 730mA I think.) Polarity's correct on both. Power is definitely getting at least from the supply into the board, I've verified that much.

 

Thanks,

-='Box=-

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Actually Japan uses 200V and NTSC, so not an issue. :) I thought Japan was PAL too for some reason, but nnnnnope.

 

That's awesome! I had no idea that they used NTSC in Japan!

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Actually Japan uses 200V and NTSC, so not an issue. :) I thought Japan was PAL too for some reason, but nnnnnope.

It's 100V, actually.

 

But anyway, to test the 7805 you'll have to use a multimeter and set it to test DC voltage. With the front of the 7805 facing you, place the red probe on the third leg of the 7805, and then the black probe on anywhere there's ground (i.e. middle leg of the 7805). If you're not getting 5V or anything close to it, then the 7805 needs to be replaced.

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Haven't checked the chips for 5V yet. I'll do that. And no, no black screen.

 

And any idea how I verify a 7805 regulator is functional?

 

Thanks muchly for the response.

 

-='Box=-

 

left pin is input

middle pin is ground

right pin is 5V out

 

its also a good place to measure resistance tween 5v and ground to see if anything is shorted

Edited by Osgeld

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I'm getting a full 10 volts on all three legs of the 7805.

 

I suspect this is...um...bad. Yes?

 

Greatly appreciate the help. I actually have an EE degree but I've been in software for 21 years and I've forgotten nearly everything but the terrible Ohm puns.

 

-=ShoEboX=-

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Finally got around to replacing the 7805 and capacitor, at which point I realized that somewhere in the midst of these adventures I'd managed to blow the fuse. So I ordered some fuses and I now await those. GAAAAAAH SHOEBOX WANT MAKE THING WORK.

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Ok! Replaced the fuse, 7805, and cap. Getting 5V on the right pin of the 7805. Throw in a cart, turn the thing on, aaaaaaand...VOILA!

 

DwRrJJkX0AAkFKX.jpg

 

Thank you guys so much for the help!

 

-=ShoEboX=-

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There's YouTube tutorials up the wazoo on repairing all kinds of common issues with old systems and doing various mods and such. What held me back for the longest time was that I couldn't solder worth a damn, but investing in an actual GOOD soldering iron and watching a few instructional videos helped a lot there. Figure out what you need to know, learn it, and give it a shot. It's surprisingly fun bringing old relics back to life.

 

-=ShoEboX=-

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