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 Post subject: Help fixing an old SNES.
PostPosted: Thu Jan 12, 2017 3:50 am 
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Hi.
I just got an old SNES that didn't work.
First I checked the fuse, it was blown. I exchanged it and them it powered up.
After powering up, I saw no image, nothing.
I took a look at the crystal and it was fine, but the trimmer was completely loose.
The trimmer was originally like this one.
I exchanged the trimmer, but I could not find the same one and used one like this one.
So far, so good, I can hear the sound though the audio output, but I only get image though S-Video and like this:
Attachment:
File comment: Title screen
20170111_211517.jpg
20170111_211517.jpg [ 730.08 KiB | Viewed 249 times ]

Curiously, after the Konami's logo, at least the image syncs:
Attachment:
File comment: Konami logo
20170111_211529.jpg
20170111_211529.jpg [ 965.24 KiB | Viewed 249 times ]

But stays distorted:
Attachment:
File comment: Boot Screen
20170111_211537.jpg
20170111_211537.jpg [ 937.5 KiB | Viewed 249 times ]


Could this be related to the trimmer not being the same as original?
I've added a capacitor as on the first link and saw no differnce, changing it's value or adding more capacitors would make any difference?
Thanks in advance.


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PostPosted: Thu Jan 12, 2017 5:49 am 
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Since you got color the freq is roughly correct so the problem is elsewhere. Since the thing kind of syncs only on brighter screens it suggests video signal isn't in spec for some reason. There should be some 220µF caps in series with composhit and luminance signal, I would look at replacing those.

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PostPosted: Fri Jan 13, 2017 2:57 pm 
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Great!!
That was it, two electrolitic capacitors.
One on "compushit" :lol: other on the luma output.
Many thanks!!


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PostPosted: Sat Jan 14, 2017 2:18 am 
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You should also replace the other e-caps, when one goes all others follow. There's a couple on audio signals, and I imagine the sound has lot less bass than it should due to loss of capacitance.

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