Super Mario 64 cart freezes after loading screen

Hi all. I occasionally buy broken N64 carts to revive them for fun and because I wouldn't mind playing whatever the game is. I've been able to get every cart working so far (about 10) by fixing continuity problems and replacing batteries. Now I have a Super Mario 64 cart that has me a bit confused. It was showing all four of the save slots as empty and it was freezing after any attempt was made to start a new game with any of those save slots. I figured swapping the EEPROM would do the trick, but nope, it's still freezing after I try to start a new game in an empty save slot.

For reference, there's no water/moisture damage to the cart and all continuity testing results are good. The original EEPROM chip from the Mario 64 cart has been installed into an F-1 World Grand Prix board (which was the donor board for the replacement EEPROM) and that game is saving just fine. I have an old DX256 that I tried to use as an alternative to the cart's EEPROM, but it seems to be dead (battery voltage is still over 3v, but all games refuse to boot with it installed).

Possible problems I'm considering so far are:
- Faulty ROM chip - Later this week I can try dumping the ROM with a V64 to see if it freezes on there too. Getting the dump to a PC to compare it to a known good copy isn't currently an option.
- Faulty CIC chip - Apparently these can fail, but I would expect that to stop the cart from booting at all.

Before I swap any more parts around I'd be happy to hear from anyone who might know what type of problem I'm most likely to have here.

Thanks!

 

If you post a photo of the board you'll help others help you

 

The board is the same one shown here.

 

Update: I had time to set up the V64 and dump the cart today. The dump plays fine with multiple different carts with a 6102 CIC in the emulation adapter. No freezing after the loading screen. This suggests the ROM chip is fine along with all traces attached to it.

Bizarrely, even having the malfunctioning Mario 64 cart installed in the emulation adapter works (game plays, saves and loads saves without freezing). For anyone not familiar with the V64, the emulation adapter disables the cart's ROM chip (loading the ROM data from the V64's RAM instead) but allows the CIC and save chips in the cart to function normally. This means the 6102 CIC chip and EEPROM chip are both working.

All that leaves in the cart is the capacitors. They certainly don't look bad, but I know that doesn't mean much. If anyone with this same cart/board has a meter and can share readings from the caps while they're still installed in the board that might be handy. Hopefully I'll have time later today to try swapping at least some of them.

Thanks again.

 

Now all of the capacitors have been swapped, and the game still freezes after the save state loading screen.

So, after many tests and some part swaps it looks like the contacts, traces, capacitors, ROM chip, EEPROM chip, and CIC chip are all okay. That seems to be everything. Of course, the cart still doesn't work correctly. All I can guess at this point is that the ROM chip could have an issue that doesn't cause problems with the Doctor V64's method of interfacing with the chip but does cause problems for N64 consoles. Either that or the CIC chip and ROM chip can't function properly at the same time (since the ROM worked when that's all the V64 was using, and the CIC+EEPROM worked when the ROM was disabled by the V64's emulation adapter).

Any feedback, thoughts, and suggestions are welcome.

 

Please take a photo. We can't very well make out e.g. corrosion or shorts you might've missed on a photo of a completely different board.

In the meantime, since you suspect the ROM, how about trying that chip on another board that's known to work? Same for SRAM (after-the-fact edit: My bad, yes this cart's got an EEPROM not SRAM) and CIC. One at a time.

 

Thanks for the response. I'll get pictures later today. No corrosion or shorts though, before and after the part swaps done so far.

There is no SRAM, just EEPROM, and that has already been swapped. I will eventually swap the ROM and CIC, but not right now. The ROM on the original board is fully readable by the Doctor V64 and the CIC seems to be working fine. There's always some risk of damage during part swaps and I'd like to avoid that. I've already had the ring for one of the ground pins on the EEPROM come off of the board during desoldering along with most of one of the leads on one of the capacitors. Also, if I simply swap both parts to another board and the game works I probably won't be any closer to understanding why things aren't working on the original board.

 

Pictures! Flux residue hasn't been cleaned up yet from the EEPROM and capacitor swaps. One of the caps is on the back now since most of one of the leads broke off of one of the donor caps during the cap swapping.