Need advice troubleshooting n64 hardware

[rad3ds]

I'm trying to set up an n64, but I'm encountering some strange issues.
I have 4 games cartridges handy to test with, Mario 64 rumble version (Japan), J League Live 64 (Japan), Rogue Squadron (USA), Episode 1 Racer (USA)
I have 2 regular jumper packs to test with, and 1 expansion pack.

The issue I am encountering is that some games don't boot at all with jumper or expansion (Mario and J League), and the other two have pretty severe graphical glitching with just a jumper pack installed, and seem to run mostly okay with some possible glitching when I have the expansion pack inserted.

I assumed this meant something was wrong with my motherboard, so I got a replacement motherboard for a reasonable price. I test with it, and I am getting the exact same issues.

It seems surprising to me that I have bad luck with all 4 game packs, is it the most likely cause? All were obtained from separate sellers online.

Other common factors are my power supply and video cable, and television.
I used a cheap multimeter to test the voltage on the PSU. The two 3.3v pins tested around 3.4v, and the 12v pin came in a little under 11v. I know it's probably not an exact thing, but does this indicate the PSU may be the culprit?

I will also lend some cartridges to a family friend who has an N64 for testing, but it will be a little while before I see him, so in the mean time, I wonder if anyone here has ideas for troubleshooting.

 

[Catastrophic]

Did you try cleaning the contacts on both the cartridges and the jumper packs? Dab a q-tip in rubbing alcohol and rub it on the contacts in a circular motion.

 

[rad3ds]

Pretty sure it's not dirty contacts, but I gave them another cleaning with some electrical contact cleaning solution. No change. It's probably going to take me borrowing a known for sure working cart, and lending the carts I have to a friend for testing, to narrow this down.

 

[cvskid]

Are you using an official n64 power supply and official nintendo av cables?

 

[rad3ds]

Both are Nintendo branded and look official to me.

 

[Razor83]

Sounds like a RAM problem. Have you tried different jumper/expansion paks?

 

[rad3ds]

Yeppers. Two different jumper packs, and an expansion pack on hand, and two different mobos as well actually. I get the same set of problems with either mobo and either jumper pack, and the expansion pack seems to fix a lot of issues with Rogue Squadron specifically, but not the other games I have on hand to test with.
I had originally assumed the built in RAM on my mobo was bad, and so got a second mobo, but surprisingly it must be something else.

 

[MarzDaindigo]

It could be the system contacts (worst fear)

 

[rad3ds]

What do you mean by system contacts?