My SNES is having an odd video issue

Discussion in 'Repair, Restoration, Conservation and Preservation' started by foldor, Dec 3, 2018.

  1. foldor

    foldor Member

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    So my SNES just started doing this thing where certain types of objects on the screen will kind of stretch a colour across the screen. I first noticed it while playing Brain Lord when anything white would smear blue across the screen. I then ran the SNES Test Cartridge where I noticed that the vast majority of the tests will look and perform just fine, but the one they call "objtest" or "Object Test" will produces the same smearing effect. But all of the other tests look fine to my eyes at least. I did notice that when I ran the controller test it works fine, but when I get the PASS confirmation it will again do the blue shift like in Brain Lord.

    The following things are what I've done to narrow down the scope of my issue:
    • Checked 4 different TV's two CRT's and two LCD's.
    • Checked 4 different AV cables, two S-Video and two Composite.
    • Checked two different OEM power supplies that are known working.
    • Done a visual check for any noticeably leaking capacitors. I'm no expert on this though.
    • Tried multiple different games, both originals and with an SD2SNES.
    • Based on a Reddit suggestion I tried tweaking the TC1 potentiometer to no benefit.
    • Cleaned the entire board with isopropyl alcohol since there was some minor flux like residue on the board (likely from the factory). Some photos below are before/after this cleaning.
    I've included an album with some photos of the problem, as well as photos of my motherboard which appears to me to be clean and in good shape, I've had this console since I was a kid.

    Album Link Here

    If anyone can take a look and let me know if they've seen anything like this before, and what might be the root cause I'd appreciate the help. At this point I'm leaning towards it being a PPU issue, which for me would mean I'll need a new console since PPU's aren't exactly up for sale anywhere I can find. Though I'm open to replacing it if I could find a good source. Anyone know of any places that would sell it?
     
    Last edited: Dec 3, 2018
  2. Tokimemofan

    Tokimemofan Intrepid Member

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    CPUs go bad more than ppus often with similar symptoms. Call it a day and replace the motherboard unless you have the equipment to replace smd components and a donor
     
  3. foldor

    foldor Member

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    Fair enough about replacing the motherboard. I do have the equipment to replace SMD components, but no donor. A quick look on eBay for me reveals no decently priced known working motherboards unfortunately. I imagine most of the time, if the motherboard is good, the case is fine as well.
     
  4. Ergot_Cholera

    Ergot_Cholera Flaccid Member

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    What is the board version? You could get a cheap Super Famicom for donor chips or just use the new board in your SNES case (swapping over reset button, power socket panel etc.).
     
  5. foldor

    foldor Member

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    Well, you should be able to see the board revision from the photos, but it's SHVC-CPU-01 all the way from 1990. One of the very first revisions as far as I can tell. I could get a cheap Super Famicom, and by the sounds of what everyone is saying, that may very well be the only reasonable option for me. I really was hoping to just repair this one if possible, but if the problem truly is just in the CPU or PPU, then I'm shit out of luck.
     
  6. zzattack

    zzattack Spirited Member

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    CPU and PPU are easily transplanted from $10 Super Famicoms.
     
  7. foldor

    foldor Member

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    I'd love to find a $10 Super Famicom. I've searched eBay, but the cheapest I can find one is $23.99 USD (~$32 CDN for me). Is there a better source for finding a cheap one?
     
  8. zzattack

    zzattack Spirited Member

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    It's been a while so maybe not as easy to find a good deal, but I've personally had 25 delivered for $250. Took two months by boat but all 10 worked.
     
  9. foldor

    foldor Member

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    Fair enough. I've bought 15 Sega Saturn's that way once, but I'm not looking to get bulk Super Famicom's right now since there's less of a market for reselling them as there is for Sega Saturn's since SNES consoles are much more common than NA Saturn's. Thanks anyways :)
     
  10. Tokimemofan

    Tokimemofan Intrepid Member

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    Chances of it being the cpu are at least 80% the balance is ppu related. shvc is garbage, if looking for a donor look for water damaged or roached units they make great chip donors, as do rgb and apu boards that are black screened, to put it simply if you replace the cpu use a b revision, I think they started using those in the late gpm boards. They fixed whatever caused these problems in that chip revision
     
  11. TriMesh

    TriMesh Site Supporter 2013-2017

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    If the test cartridge is not reporting any errors then it's almost certain that the CPU is good. It could be bad a PPU, but judging from the screenshots, it could also be bad video coupling caps - try getting a 220uF cap and connecting it across C58 or C60 and see if the video improves (you don't need to remove the existing cap for this test) - if that fixes it, then replace all the video coupling caps (C65-C60).
     
  12. rama

    rama Gutsy Member

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    +1 for the video coupling caps. Easy repair :)
     

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