SNES console problem

Hey,

Thought this would be the best forum for this. I have a super nintendo that previously worked fine
but now when you start up a cartridge it plays for about a minute then the graphics get all garbled
and it hangs\crashes. I have no clue what could be wrong. I thought it might be the voltage regulator
maybe (??) but I figured I'd toss this post up first before messing about if someone else on the forum
has delt with a similar issue before.

Cheers,

Shawn

You should measure your regulator output after it hangs up. Might be heat related so you should also feel the chips for being too hot... Maybe a bad cap on the power section..... Maybe your power brick is failing too.

After all these, it could be anything... Hope this helps.

The regulator is gonna be my first suspect to interrogate. After that I'll take a look at the caps. God I hate cap jobs cause it's damn near impossible to find the culprit unless one totally fries so you end up replacing half or more of the damn things. I'd end up probing the whole damn motherboard to find one fried cap with my luck.

Yeah, but 20 year old caps ought to be replaced anyways.... They are way beyond their life expectancy.

wasn't the regulator. 8 zillion little caps are looking very overwhelming right now.

After it stops working, is anything particularly hot?

Only the electrolytic caps I was referring to.

Does it happen on every game? My old SNES had a similar issue where graphics would go distorted only on certain games like Tales of Phantasia or DKC. After a bunch of digging around and asking on different forums it was figured that my PPU or VRAM were probably dying...so I just bought another system.

Wish I could help with this kind of thing, but I actually have a bizzare console problem myself. I have one SNES that works perfectly fine with every game I own except Dragon View, which loads with a garbled power-up screen and "loses" graphics in specific ways while playing (eg/ everything is fine until you open the menu in a dungeon, after which everything except your player and the status bar goes black and doesn't seem to come back until you change regions or something). I've tested it over and over and it's perfectly reproducible, no other game seems to have problems and I've confirmed for certain it's not a problem with the cartridge either.

The game seems to play fine, it's just the screen that's messed up. Given that the title screen loads with some tiles correct and some not, my best guess is maybe one bit of a VRAM address bus is broken but I really don't have a clue. If it's possible to diagnose something like this and anyone knows how, I'd be glad to waste a day poking around to figure it out.

I doubt his problem vram or ppu related. Even though strange tiles and things go on the screen, his SNES actually crashes, while if there were a problem with either of those, the game would at worst show a black screen, but you would still be able to interact with it. I'm curious, but does the audio get messed up too? usually if the game crashes, the audio still plays because it is almost a separate system from the rest of the SNES (I think it's only connected by 4 busses?) However, if there was a power supply problem, I imagine both would shut off or do weird stuff. (I'm no expert though.)

If the PPU stops generating NMIs, it could cause games to freeze.

To narrow down whether it's an audio problem, try one of the games whose sound drivers rely on constant communication over those four I/O ports.

Which means you never got to know for sure what the problem was.

Something similar happened to me. Our old family SNES started not working properly with certain games. F-Zero had screwed-up Mode 7 maps, so that you'd be driving on city instead of track, and would thus lose health and eventually blow up. Super Mario Kart was perfectly playable, but the Mode 7 graphics at the victory screen (the fish and the congrats message) were not there. Yoshi's Island had garbled backgrounds with wrong tiles and colours, but was also playable. Super R-Type worked perfectly as far as I could tell. Super Metroid looked fine until you realized that the map didn't show up, and that certain powerups were missing, resulting in a dead end.

So I bought a replacement.

My hardware expertise is limited to the lab portion of an electrical engineering lite course I took as part of my mechanical engineering undergrad over a decade ago, so I haven't even opened the unit up to see if anything obvious is wrong (leaky cap or some such)... It'd be cool to get it fixed at some point, I guess, if it's possible...

Oh yeah... (I guess vram still isn't an issue, unless I'm not thinking again.)

Also, since I have no kind of electrical engineering background, what are "caps"? are they these things? What do they do? What do they contain, some sort of battery acid? (I looked up electronic caps on Google, but I just got some sort of company.)

Capacitors.

They're these: wikimedia:aluminum electrolytic capacitor cutaway view

Those are all electrolytic capacitors. The silver and black ones are just surface-mount versions, while the ones with the blue and white "wrappers" are through-hole. Functionally, they are identical.

To visualize what they do, think of them like a really small battery that takes maybe a second to charge or discharge. What happens is that the voltages on the various signals or power lines aren't always "clean" meaning they will vary up or down from their intended voltages, either due to radio signals being picked up by the copper traces like an antenna, or just due to the imperfect nature of the components, or various other reasons. One of the two main issues that are overcome by capacitors are large, singular fluctuations that can be caused by things like plugging in a controller, because the instantaneous change of suddenly having to supply power to a whole new device can actually cause the power rails to drop in voltage because they can't immediately adjust to the change. So when that happens you put a really big capacitor on the power line to "help" the power supply to maintain it's proper level. The "battery" will only last less than a second before it's completely discharged, but that's long enough for the power supply to get back to where it needs to be, at which point the power supply will "recharge" the capacitor so it's ready in case it happens again. The second issue is radio interference (which isn't always actual radio signals, but every electronic device generates electromagnetic fields which are basically the same thing). This interference is really fast, but not very large in terms of the amount that the voltage changes. However, sometimes this "noise" is actually enough to cause glitches, so for that they use really small capacitors which are basically constantly "charging" and "discharging" in order to smooth out the rapid up-and-down on the data lines.

Electrolytic vs ceramic capacitors are just two different kinds made of different materials which each have their pros and cons for specific applications (through hole ceramic caps typically look like this but there are variations). Ceramic caps can't be reasonably made in large sizes, so they are typically used for the second scenario, for filtering small high frequency signals, whereas electrolytic capacitors can be made in much larger sizes, but are much more prone to failure over time because of how they are made. For that reason, it's much more likely that the electrolytics need to be changed rather than the ceramics. Electrolytic capacitors don't contain "battery acid", they store their small amount of charge on a plate, much like if you have ever rubbed a balloon against your head and stuck it to the wall from the static, the electricity is stored on the surface of the balloon because it has no conductive path to ground.

Wait a minute, then why do people always complain about the capacitors ruining old consoles? the picture right there is of the SNES motherboard (only board, really) and, like you said, they don't contain any battery acid, so they shouldn't really break the console if they do, you just have to replace them more often, which I can't imagine being the hardest thing to do. (I imagine it would be harder to replace the ones that are stuck to the circuit board, then the other ones where you could probably solder the two "poles" onto the board.)

Electrolytic capacitors don't contain battery acid, but they do contain an electrolyte. In the case of the cheap and widespread aluminum ones, that's a liquid (and therefore capable of leaking). It's often not the nicest of chemicals, either. Wikipedia has a huge article about it, too.

So I did some more poking at my broken SNES today out of curiosity... I don't know how I ever thought Dragon View was the only game that's broken, because I'm getting the same kind of thing on everything I try long enough now.

Most common problem is BG layers just plain disappearing, turning solid black. Occasionally some garbage appears on screen. Sometimes sprites disappear too - Mario disappeared between rounds of Mario Kart, turning it into an awkward first-person-perspective game. What is REALLY bizzare though, is that in Dragon View the sprites of all the objects on the world map jitter around. They'll flicker back and forth, sometimes not just a pixel or two but nearly half a screen away, while you're standing still.

All the while the games run perfectly fine, it's just a graphical problem. Something inside the PPU is shot...

Is it possible to repair a problem like this? Can you just find and swap out a chip maybe, if someone still makes them?

EDIT: JUST as I say that, I notice that mario kart seems to have gone into an infinite loop after the race and isn't responding to controller input. I don't know what's going on anymore.

Yeah, Mario Kart is reeeally broken. I finished the second race, got a "Game Over", then another race starts but I can't move...