So a buddy of mine handed me a bag of about 15 dead NES carts. No idea what's wrong with them, other than "they don't work." 

There's a Ninja Gainden 3 in there, so I figure it's worth a few minutes of my time to go over these.

Aside from the obvious cleaning pins, etc, what should I be looking at with these? What are the common failure points on a NES cart?

I would just open them up and clean them with Weiman's then 91%. That'll likely bring most of them back to life.

Usually the cauae is dirty pins. Depending on how dirty they are is what you might want to use. If cleaning them doesn't work then someone on here can probably help you would with a pic of the pins as you might have other issues with the game.

I've got a bottle of barkeeper's friend. Will that work for polishing the pins?

That might be too abrasive. Try 91% alcohol (like $2 at Wally World), and if that doesn't work, try some Weiman glass stove cleaner (another $2) applied with cotton swabs, then an alcohol cleanse.

 

When I'm fixing problem carts I check for:
Visible corrosion
Dead mask rom
Flaky ram
Problem board/mapper chip/other

In most cases my fix is a board swap. That covers the first and last cases as it's usually too much work to locate specific issues.

Ram chips can be swapped if they are suspect. This mostly shows up as graphics noise for chr ram games. Or failure to save for battery backed games.

Dead mask ROMs are least common. Chips can be pulled and dumped individually to verify. That requires a replacement, which almost always will be an eprom which hurts the value of high dollar games since you're giving up authenticity.

The next step is to take a midnight train going anywhere

I have some PCBs posted on OSH Park that will allow you to dump NES Mask ROMs on a standard EEPROM programmer

PRG ROMs
https://oshpark.com/shared_projec...

CHR ROMs
https://oshpark.com/shared_projec...

MMC5 / SNES
https://oshpark.com/shared_projec...

Two of the carts boot and run (Contra, Zelda) but they have graphics noise. 1 cart boots, but freezes at a static image (Zelda II)

Three of them do absolutely nothing (Ninja Gaiden II, III, and one more I can't remember)

There's some SNES carts in the mix too - I'll have to dig out my console to test those.

Contra and Zelda both use CHR RAM so that may need to be replaced, could be a bad trace also

Zelda 2 might be bad PRG RAM

Ninja Gaiden 2 and 3 do you get a blinking power light if testing on a front loader? Solid color screen could be a few different things also

I've resurrected Game Boy games by re-flowing the solder points on every chip. Probably a 95% success rate for games that are still buggy after a good cleaning. But those use surface-mount chips that I've never seen on NES games. Still, I'd at least try that before swapping chips out.

^^^I was going to say that some of the surface mount MMC chips might need re-flowing.

Use all these suggestions and keep trying to get them working.

If not, do what John Cena did:

http://nintendoage.com/forum/mess...

Keep us posted! A lot of times they only need a good clean. I got a dead Supergrafx for cheap that only needed to have its pins thoroughly cleaned. Works like a charm now