Help fixing an old SNES.

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Fisher
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Help fixing an old SNES.

Post by Fisher » Thu Jan 12, 2017 3:50 am

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:
Title screen
Title screen
Curiously, after the Konami's logo, at least the image syncs:
Konami logo
Konami logo
But stays distorted:
Boot Screen
Boot Screen
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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TmEE
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Re: Help fixing an old SNES.

Post by TmEE » Thu Jan 12, 2017 5:49 am

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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Fisher
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Re: Help fixing an old SNES.

Post by Fisher » Fri Jan 13, 2017 2:57 pm

Great!!
That was it, two electrolitic capacitors.
One on "compushit" :lol: other on the luma output.
Many thanks!!

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TmEE
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Re: Help fixing an old SNES.

Post by TmEE » Sat Jan 14, 2017 2:18 am

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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