kiltro
.
- Joined
- Sep 6, 2025
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Hi all,
I have a PAL Nintendo 64 (NUS-CPU(P)-01 with DENC-NUS). Initially the console wasn’t outputting video. I disassembled it, cleaned everything, and surprisingly it worked again. After fully reassembling it with heatsinks and screws, the console stopped working (no video on TV). I had to disassemble it again to run tests.
Currently: console powers on (red LED on), but TV shows “no signal.” With the oscilloscope, I see a composite signal (~350 mVpp, ~4.46 MHz) on the “C” pin and at DENC pin 20 immediately after power-on. After about 1 second the signal collapses to DC and stays flat. The TV never shows an image.
What I’ve checked so far:
• All power rails remain stable (12 V, 5 V, 3.3 V)
• Reset behaves normally (stays high, drops when reset button is pressed)
• 17.7 MHz clock present and stable
• FSC at 4.43 MHz appears briefly at startup
• CSYNC (DENC pin 15) rises to ~2.5 V then drops to 0 V
• Data lines: D0–D3 show ~12 MHz activity (~1.4 Vrms), D4–D6 stay flat at 0 V
• DENC pin 11 (clock in, ~50 MHz) stays active even after composite disappears
• No R28 jumper on this revision
• Cartridge slot and Expansion Pak connector cleaned, tested with known-good cart and Expansion Pak
• Power switch and LED work normally
So the DENC gets clock and power but loses sync and stops producing video after ~1 second. Since it briefly worked after cleaning but failed again after reassembly, I suspect mechanical stress: heatsink screw pressure flexing the board, cracked QFP solder joint on RCP/CPU, or a connector not making full contact.
Has anyone seen this exact behavior? Would you recommend reflowing the RCP/CPU QFP pins, or should I focus on checking the cartridge/Expansion Pak connectors again even if they look clean?
Any insight or confirmed repair stories would help a lot. Thanks!
I have a PAL Nintendo 64 (NUS-CPU(P)-01 with DENC-NUS). Initially the console wasn’t outputting video. I disassembled it, cleaned everything, and surprisingly it worked again. After fully reassembling it with heatsinks and screws, the console stopped working (no video on TV). I had to disassemble it again to run tests.
Currently: console powers on (red LED on), but TV shows “no signal.” With the oscilloscope, I see a composite signal (~350 mVpp, ~4.46 MHz) on the “C” pin and at DENC pin 20 immediately after power-on. After about 1 second the signal collapses to DC and stays flat. The TV never shows an image.
What I’ve checked so far:
• All power rails remain stable (12 V, 5 V, 3.3 V)
• Reset behaves normally (stays high, drops when reset button is pressed)
• 17.7 MHz clock present and stable
• FSC at 4.43 MHz appears briefly at startup
• CSYNC (DENC pin 15) rises to ~2.5 V then drops to 0 V
• Data lines: D0–D3 show ~12 MHz activity (~1.4 Vrms), D4–D6 stay flat at 0 V
• DENC pin 11 (clock in, ~50 MHz) stays active even after composite disappears
• No R28 jumper on this revision
• Cartridge slot and Expansion Pak connector cleaned, tested with known-good cart and Expansion Pak
• Power switch and LED work normally
So the DENC gets clock and power but loses sync and stops producing video after ~1 second. Since it briefly worked after cleaning but failed again after reassembly, I suspect mechanical stress: heatsink screw pressure flexing the board, cracked QFP solder joint on RCP/CPU, or a connector not making full contact.
Has anyone seen this exact behavior? Would you recommend reflowing the RCP/CPU QFP pins, or should I focus on checking the cartridge/Expansion Pak connectors again even if they look clean?
Any insight or confirmed repair stories would help a lot. Thanks!
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