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.
Also, if you have visuals on screen but they are corrupt, a great visual reference guide is here https://www.projectvb.com/nss/logs.htmīģŋ
- 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).
A good test if the CPU or PPU are faulty is to use a Super GameBoy.
If you insert a Super GameBoy of the correct region into the SNES, with a known working game, then turn on, observe the results.
- No / Black Screen > Dead CPU
- Super GameBoy Border but no Game Load > Dead CPU
- Super GameBoy Fully Works > Bad PPUs
Of course no/black screen could be power, video encoder or AV output issus too, or even RAM, but in most cases it is the CPU.
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.
