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Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 11:18 am
by waga
I have a strange problem with US Castlevania PRG1 on a Famicom AV using a tototek nes to Famicom adapter. The title screen looks fine, the intro looks fine, but when the game starts, the screen flashes white and the background colours look off. When I enter the castle, the background turns pink. When I keep playing, on level 2 where the traps are, the screen refuses to scroll anymore.

I though I had a cart with a bad rom, so I bought another one and I have the exact same problem!

I know there are issues getting Castlevania 3 to work on a Famicom, but this is the first I've heard of a problem with CV1. I've been looking for at the pinouts for the cart and the adapter, and I wonder if there's something I need to alter on the adapter side, similar to the CV3 mod where you add resistors.

I'm not convinced that I've somehow managed to get 2 bad carts, so I suspect the adapter at the moment. The adapter works with other games, including CV2 and both Zelda games, although I don't have another UNROM game to test. I also dont have another console.

Has anyone encountered anything like this before? I've cleaned the pins with alcohol, they were already pretty clean to begin with. And on the first cart, I reflowed every solder joint and it didn't help.

Edit: I recorded some videos. The first one shows the white flash and the strange colours of the statue. Although the background inside the castle didn't turn pink this time. The second one shows the pink background appear and disappear as I went up and down stairs. And the third is a new problem, rather than the game refusing to scroll horizontally on level 2, it slowed right down to a crawl.

https://youtu.be/SSTX1x3xy3U

https://youtu.be/iSTrOEMtIvI

https://youtu.be/a1I0Gh0pklw

And as I was uploading these videos, I left the game at the title screen with the demo looping, then it froze after 10 minutes.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 12:16 pm
by Jeroen
Perhaps one of the adress lines is not coming through right? This way the code portion of the rom might be fetched correctly, but some data or specific pieces of code aren't loading correctly?

If you have a multimeter you can use it's continuity mode to see if each line is ending up at the proper point on the cartridge slot.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 2:05 pm
by waga
I tried that with my first cart, I took apart the adapter and plugged CV in, then checked continuity through both the cart and adapter together and everything rung out ok. Although I wonder if you are on to something with the address line. Maybe CV used one pin extensively for a certain address that it doesn't for other carts, and the adapter has an issue on that line that doesn't affect other games. I plan on getting a different adapter to check.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 2:28 pm
by Jeroen
What's wrong in the last youtube video?

edit: oh the game slowed down a lot, wth?

edit2: you're not using a hidef nes mod by any chance right? It's been known to be a bit flaky depending on cpu revision (especially with palettes since it intercepts those). Also it messes with the cpu speed, so maybe something is up there.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 2:32 pm
by waga
The speed slows to a crawl. It looks like the video is in slow motion but it's the game. It's totally fine before that room then as soon as you get control after the screen transition it slows. It stays slow to the boss, and as soon as I collect the orb, the speed returns to normal. It's strange.

Edit: no hi-def nes mod, but it's been rgb modded professionally. I'm also using it with an OSSC.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 2:33 pm
by Jeroen
Ya I saw that right after I posted, see my edit above for more questions.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 3:10 pm
by Jeroen
Mmm the only thing I can think of that could cause the game to slow down is if the NMI line is intermittent, the game logic won't update at 60hz but at whatever rate is coming through on the pin. (could even be random noise!)

Overall you might want to reseat the connections, since the palette is also acting up.

edit: that is the connections of the rgb mod.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 3:29 pm
by waga
Something I forgot to mention is that Castlevania plays fine on an everdrive, and on the fdsstick through the ram adapter. It's just the original cart that gives me trouble. I've had the rgbmod for over a year now and I haven't had any problems at all so far.

I've ordered another Famicom to nes adapter so I will try that when it arrives. Thank you for your advice so far. I'll update when the new adapter comes.

If this doesn't work I'll check the rgbmod and make sure nothing looks off, no dry joints or anything. I need to read up on what each pin does in the carts too.

Re: Castkevania problem with Famicom AV

Posted: Sat Dec 08, 2018 3:39 pm
by Jeroen
Certainly strange that it would work with an everdrive...But I'm fairly confident the NESRGB mod is causing the issue here.