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View Full Version : SNES SNS-CPU-GPM-01 boots to logo then nothing else



Niku-Sama
06-04-2015, 03:32 AM
ok so before I go drilling on this thing I want it to work to begin with.

long story short you can get some games to start up with their company logo but then nothing after.
Mario Kart shows the Nintendo logo in white and stays there
Blazeon has the Atlus logo rotate in one letter at a time and then fade to black with nothing else coming up
Gradius III shows a white grid that doesn't go away.

that's normal for gradius when the game starts normally it flashes a white grid before going to the Konami logo and starting the game.

I'm curious if theres any thing else I should check before diving into caps.

board and connector (both sides) have been cleaned thoroughly.
games mentioned above work fine in another system

Thrillo
06-08-2015, 08:09 PM
My guess is that it's a cap issue. Look around the internet & lots of folks (including me & my 5 SNES/SFCs) have been having similar issues over the past few years. Some games play fine, others just act bizarre & won't go past title or loading screens. I took it as an excuse to upgrade to a modded SNES Jr.; I never did figure out exactly what the problem is.

Niku-Sama
06-17-2015, 05:31 AM
so I had done some more poking around and reflowed a lot of common solder points that go bad, same thing. tried a few jumps on the board, same thing.
I had read one instance of the 7805 going out could cause that, makes sence, not getting enough juice wont initialize properly....something different.

I turned it in with the new 7805 in, the power light flickered on and then right off. figured I blew the fuse, nope still have continuity across that, and proper readings on the little block thing right behind the jack. the only other thing I could think of was what ever cap was the worse is not completely gone now.

I tested the old 7805 out side of the system and it tested out within spec, a little low but within spec none the less. so I go to replace it since theres no reason to keep the other one in there because its a bigger size and cant screw it down to a heatsink big enough for it and the via's came out with it on the input and ground pins.

the pads on the top and the bottom are intact and as far as I can tell its a 2 layer board so it might still work but that just pissed me off to no end so its in the spare parts bin, I may come back to it some day but not any time soon.

the 7805 I used was bigger than the 220 size that was in the system I'm not sure what size it was but its leads really dug into the via almost like they cut into it and it gripped them as it was de soldering and that's how they came out, probably why they came out so cleanly

APE992
06-22-2015, 01:08 AM
My guess is that it's a cap issue. Look around the internet & lots of folks (including me & my 5 SNES/SFCs) have been having similar issues over the past few years. Some games play fine, others just act bizarre & won't go past title or loading screens. I took it as an excuse to upgrade to a modded SNES Jr.; I never did figure out exactly what the problem is.

No, not everything is a cap issue despite that being all the rage amongst "modders" to claim. Caps are going bad in a lot of consoles due to age, more so with those that have surface mount caps like SegaCDs and GameGears but this smells more like a trace is damaged, a chip is damaged, or (remotely) the system isn't getting enough juice. Electronics can act in unexpected ways when there isn't the correct voltage or current levels being supplied and original OEM power supplies can and do act up due to age. Not always but worth a try as it's cheap.

Good luck fixing a bad trace without visually inspecting every square centimeter of the board. Sometimes you can narrow down where to check based upon symptoms but I'm not enough of an engineer to field a guess at where to look.

Niku-Sama
06-24-2015, 01:53 PM
Umm these are surface mount caps and they are the same age as a Sega CD