Visual Diagnostics (SNES)
In order to find faults on the SNES, it is often more useful to diagnose visual outputs then probing with an oscilloscope as almost all faulty SNES consoles are bad chips, not traces, and the failed chips always seem to die in a way where the waveforms are completely normal looking.
- Make sure you have a game in
- Check your fuse or bridge it
- Check reset button isn't stuck down
- Check CIC is ok or use Flash Cart to bypass it
- If there is S-CLK 8 pin chip on board, inspect it and reflow pins
There are several steps to black screen. This can be a bad CIC, CPU, Work RAM, PPU or Video RAM, or even S-ENC (uncommon).
To help identify if the PPUs are faulty, insert a Super Gameboy into the console and power on. The Super Gameboy doesn't use the PPU's so if they are faulty but everything else is ok, this would show the Super Gameboy interface on screen. No Game Boy game is required to be inserted.
If with a Super Gameboy inserted it is still blank, it could still be anything, however if it does work, it proves the issue is the PPUs.
If the Super Gameboy test still didn't work, try inserting Super Ghouls & Ghosts, or Donkey Kong. These games often show the initial CAPCOM or RARE intro screen, then black screen after, if the CPU is bad.
If you have one of the SNES Burn In Cartridge you can try that to see if it loads and then you can run the burn in tests to test work RAM, PPUs and other parts.