SNES stuck at copyright screen

Recently acquired a SNES (NTSC SNS-CPU-APU-01), seems to be in good shape, mother board very clean with no visible damage, cart slot has been cleaned. It powers on fine, resets fine. The issue is that it stays stuck at the 'copyright' screen (well with some games it's a black screen, others it shows the copyright info). Games that show the copyright info are: Doom, Street Fighter 2 Turbo, Rockman X3 (I think most capcom games).

From what I have read online it sounds like this might be related to sound? I do not currently have a diagnostic cart but I'm working on acquiring one. Any other games that might be useful to test it with?

I have already replaced most of the caps (still need to replace C12 & C13). I notice that the voltage regulator gets quite hot, but it does have a heat-sink (and I imagine if that wasn't working, the system wouldn't power on at all).

I would appreciate any input or advice you may have. Thanks.

EDIT: So I finished replacing the caps, no difference. I also checked the voltage regulator and I'm reading 12v on input and 5v on output, which looks to be perfectly normal.

 

Try verifying the continuity of your reset line across the board. Make sure it hits your sound chips.

 

<deleted the previous post so people don't find it and get wrong information>
EDIT Ignore all of that, I was completely off base there. Using the cartridge slot I was able to find the reset line, and it does look like it goes all the way to the audio processor (at least with a continuity test).

EDIT2 I'm starting to suspect the S-APU IC is just dead on this system. Found this very helpful blogpost here: http://smilecitrus.info/?p=3171 I'll update this thread once I get a diagnostic cart and can confirm the issue.

 

It could be possible that when it goes to a copyright screen it does a checksum, maybe for anti-piracy. If it returns as invalid it could stop the game from continuing. Most games do have some sort of anti-piracy screen where if it would fail then it would display the screen.

I know Rockman X3 has a special chip designed by Capcom for displaying wire frames. See if it will do the Cx4 test by holding B on controller 2 before turning it on and then hit the power button.

I can't remember if DOOM has something special inside of it.

 

So I was able to access the CX4 debug test on X3 and everything passed:

http://i.imgur.com/1SUTnML.jpg