NES RAM Replacement

[Spatula Tzar] Turned on her NES one day to find it no longer working. Off went the case and out came the oscilloscope. After probing around for a bit, she found that one of the RAM chips was very hot. She hot aired off the bad chip implementing an “Impenetrable Aluminum Heat Shield of Science” to protect the rest of the components. In the chip’s place she soldered a wide DIP socket for which the NES engineers had thoughtfully left a place. Then, using a 128Mbit SRAM SOIC, she soldered it to 0.100″ headers to fit in the socket. As the original chip was only 16Mbit, unused address lines are tied high or low. The console is now fully functional again. Also checkout the comments on Oldschool NES ‘repair’ how-to.

Comments

  1. Spork says:

    Very cool to repair an NES… That board she added could use some cleanup.

  2. Nemo says:

    Oh hush, it looks beautiful, and definitely a grand hack indeed :D

  3. Sprite_tm says:

    Are you sure the amount isn’t in KBit? 2 megabytes of sram sounds like a bit much…

  4. @Sprite_tm is correct, of course, The chip (cy7c1009b) clearly pictured in this article’s picture is 128K x 8 SRAM.

  5. Paul Potter says:

    Top marks for the repair.

  6. osgeld says:

    cool repair! the workmanship looks ok, Ive seen better but never produced better myself, so what can ya say

  7. cantido says:

    or… she could have just sourced the right part and soldered it in.

    Is use of basic knowledge “hacking” now?

  8. Spork says:

    @cantido if you read, she could not source a PDIP version, which would have taken care of much of the mess. Also it is more of a “hack” if you’re not directly replacing with the same part, but making a readily available part work in your application.

    Also I didn’t mean to be overly critical in the first post, I really did enjoy the hack, I just like to make hacks look ‘pretty’ when I can.

  9. CircuitMage says:

    What? Girls don’t play video games! Shenanigans!

    Awesome hack for that guy though. :0

  10. blue carbuncle says:

    Very Impressive!!! Keep up the good work sister!

  11. Lupin says:

    I think the easiest way to remove through-hole components is to cut the IC pins with a plier and then remove every pin using a desoldering pump.

  12. Davo1111 says:

    Well done OP, looks great :)

  13. nubie says:

    @ Lupin, maybe some people don’t own side-cut pliers and a desoldering pump?

    Personally I just pry on the chip and heat each pin one at a time and it comes out slowly but surely.

    The easier way (without desolder pump) is to use desoldering braid to suck out the solder around the pins, usually only a couple will stick and you can wiggle those, then the chip drops right out.

    Also less destructive if you are salvaging the chip.

    Cool hack. I also found a hackable RGB to NTSC chip in old PSX consoles, useful if you want to make a resister ladder for DAC output in color from a microcontroller.

  14. octel says:

    @Lupin
    The easiest way to remove through-hole components is with a Hakko 808 (or clone). Very popular for arcade/pinball machine repair

  15. tehgringe says:

    I just apply the heat gun to the ‘underbelly of the beast’ and pop it off without distressing the pins…wiggle wiggle…

  16. HrPuffnstuff says:

    Back in the day we used to use an IR thermal camera to spot bad chips on flaky circuit boards. We would do scans inside newly installed equipment and when we got lockups or wierdness possibly due to heat, we got out the camera, found the offending IC which was usually much warmer than normal and replaced the IC (usually a 74xx) and moved on.

  17. Ted says:

    Oddly enough, the first thing I thought was “why didn’t she have a stash of old SRAM chips laying around”. I have at least 8 of those particular chips in a tube around here somewhere.

  18. Rachel says:

    Author here. I realize a PCB would have been much nicer looking, but it would have been more work to design and etch it than it would be to simply wire it up like I did. It was only a single chip anyway.

    You’re right about the SRAM sizes. I fixed the website.

    I’ve used the side cutters + desoldering method in the past to remove ICs, but frankly a heat gun is easier. Point it at the board for 20 seconds, and the whole chip pops out easily. I probably could have done without the heat shield on a board with such hardy logic chips, but I wanted to make sure I didn’t screw something else up.

    @CircuitMage, yes, girls play video games. We also fix them when they break. Scary, huh?

    Thanks everyone!

  19. Marvin says:

    oohh.. that sounds like a dream come true :D

  20. Hitek146 says:

    Nice work, Rachel. I remember browsing your site a while back for some other project, looking at your site graphics and then reading your letter to the editor, and then wondering if you were American or Russian… :)

  21. wilfite says:

    @nubie, that’s a good way to destroy the vias in a multilayer PCB.

  22. avrnut says:

    Good job. I also dig the periodic table on your site – thx

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