Famicom Polarisation Question

[Eightbit Allstar]

Just bought a Famicom recently and I wanted to know how to power this baby. I already bought a power supply for 230V AC->9V DC (1400mA) but I don't know how the polarity has to be set. I've heard that the center has to be negative while the outside has to be positive. Is that right?

EDIT: My researches happened to be correct. Negative tip. However I got another problem. See next post.

[Eightbit Allstar]

I tried out a few Famicom games and some don't work properly.

Gradius 2 - Objects can't be shoot sometimes / hitboxes are way off.

Lagrange Point - No sound from sound expansion channels.

Could it be that those problems happen because I use a PAL television? Or might the Famicom have a malfunction? Other games such as SMB or Dragon Quest 2 run without problems. I need some serious help here. :-/

Btw. I use an AV modded Famicom.