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Repair guide

SNES and Super Famicom will not power on

Start with the cheap external checks, then look at the reverse-polarity diode and decoupling capacitors that commonly kill the power path. Board references are for specific revisions, so match them to your board.

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Diagnosis · Careful · about 60 minutes. Worth doing. Reports say this fix helps on many machines.

You are in the right place if: No power light, no picture, nothing happens when you flip the switch.

Before you start

  • Work with the console unplugged. The adapter is external, so there is no mains inside the console, but the power stage can still hold charge briefly.
  • Do not guess at part values. Board revisions differ, and the D1 and C30 references come from specific boards.
  • If you cannot find the fault in an hour, stop rather than replacing parts at random.

Board revisions and models

The D1 repair was on an SHVC-001 board. The decoupling capacitor short was reported on a different SNES board. The Jr. SNS-101 has only one board revision.

Parts you may need

  • SB20-03P or equivalent Schottky diode. used for the D1 swap on a Super Famicom Amazon · eBay
  • Replacement SNES AC adapter. if the adapter is the culprit Amazon · eBay
  • Ceramic decoupling capacitors. only if a short is found Amazon · eBay

Tools

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Step by step

  1. Check cable and adapter Clean the AC adapter plug and console jack with isopropyl alcohol, dry them, and try a known-good adapter. The North American SNES uses a unique plug, so do not force an NES adapter.
  2. Check the switch The power switch may be disconnected or worn. With power off and unplugged, confirm the switch is seated and clicks properly.
  3. Open the console Unplug and remove the screws, then lift out the board. Photograph the layout and the DC jack area.
  4. Inspect the input stage Look for cracked solder joints at the DC jack, burned parts and any lifted pads.
  5. Test the D1 diode On a Super Famicom SHVC-001 the D1 diode protects against reverse polarity. With the unit unplugged, test it with your meter's diode mode and replace it if it fails.
  6. Check for a shorted power rail Measure resistance from the power input to ground, unplugged. A very low reading points to a shorted component, often a ceramic decoupling capacitor.
  7. Find the short If the rail reads low, compare readings across likely capacitors. Continuity across a decoupling capacitor means it is shorted and needs replacing.
  8. Replace the failed part Use a part with matching ratings. For D1, one restorer used a 2A 30V Schottky diode.
  9. Reassemble and test Reconnect AV and power, test with a known-good cartridge and watch for heat in the first few minutes.

Tips, tales and maybes

Found in write-ups and forum threads. These are other people's reports, not tested by us.

  • Story (Medium confidence). A Super Famicom with no power was brought back by replacing the D1 diode with a Schottky diode. Source
  • Story (Low confidence). A thread on a dead SNES traced the lack of power to a shorted ceramic decoupling capacitor after the fuse, transistor and choke had been replaced without result. Source
  • Tip (Medium confidence). iFixit's troubleshooting page also lists a disconnected or faulty power switch and a dirty power cable plug as causes. Source

Guides we used

We wrote the steps in our own words from these. They have the photos and the full detail, so please read them and support their authors.

Boards and models vary, so check what is in front of you. A repair can involve hot tools, chemicals and, on some machines, dangerous voltages. You do it at your own risk.

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