SNES corrupted graphics and no sound

Hello. My parents sent me my old SNES, which had a broken power jack, so I changed to one that fits the super famicom power adapter. Now the SNES turns on and when loading the game all the graphics are corrupted. I get no backgrounds, and after pressing start it blacks out completely, there's also no sound. I have tried both the american and japanese versions of Yoshi's Island, as well as Donkey Kong Country 3 (those are the only games I have at the moment), and I know all of them work because I play them just fine in my super famicom.

This is the earliest version of the SNES, which has the sound module as an Add-on board. I tried cleaning the and reposicioning the 62 pin connector with the same results.

I've read this is probably a PPU or V-RAM issue, but I also read that it could be the capacitors. Do you think the problem lies in the onboard chips? Or could it be the capacitors? After all the waiting and retrobrighting is a shame it has to end up this way.

 

I personally think it's more likely the PPU or V-RAM than the caps, but the conventional wisdom is to always change electrolytic caps first and then troubleshoot the chips.

I'd clean and reflow the legs of those chips before I chucked it in the parts bin though.

Test with DKC3 instead of Yoshi's Island. Yoshi's Island is a SuperFX game and that's one more variable to consider.

 

Thanks for replying!
That's what I thought too, but I already placed an order for the caps. Might as well give it a try.
One more question though. I couldn't find those 100uf 6v capacitors, so I bought 6.3v capacitors instead. Are those gonna work or do they have to be the exact voltage?

 

6.3 is fine

 

You can (almost) always use caps that have a voltage rating that exceeds the voltage rating on the original cap, but you should never replace it with something that is less than the original cap (unless you've done the math and know that it was over specced in the first place).

 

Jose , check for any broken traces going to the chips you mentioned as well

 

Thanks a lot guys! I appreciate it. I'll keep you posted with the results. I don't have my hopes high but they're there nonetheless

 

Hello guys. Today I replaced the capacitors and I'm still having the same issues. Glitched graphics and no sound. I even tried the sound module from my super famicom to see if I could still get sound with the same result
So I guess that means there's not much else I can do. As for reflowing the chips I think I haven't got the necessary skills or tools to do that. A real bummer.

PS. I'm using a SCART NTSC RGB cable to connect it to the TV, and that's the only cable I have right now. Do you think maybe if I use a composite cable I would have a chance? I can't use an RF adapter because I'm living in Europe and my TV here doesn't have the correct jack.

 

Jose - I have a few questions for you on this one.

1: You said the power connector was broken, you replaced it with a Super Famicom power adapter, and you are living in Europe. Are you using an American SNES with a Japanese power adapter hooked up to 220v via a step down convertor? I am trying to get an idea of your wall power/AC adapter/SNES unit origin.

2: What power are you getting at the cartridge connector? Have you checked the voltage with a multimeter?

3: s8n asked about checking for broken traces, and that is what I have seen when I work on SNES systems. There ends up being something wrong with the signal path - various cart connector pins (assuming everything is clean) aren't getting to where they need to go due to bad traces and/or traces to the RAM chips are broken. Check your signal paths.

 

1. I think I didn't explained myself there.. Sorry This is an american SNES, which had a broken power jack, so I replaced it with a standard 5mm/2mm female jack from ebay, which fits the super famicom male jack, I have a 10V 1A power adapter that powers the super famicom, and hence the SNES. I know is a little "twisty", but it works really well. All the polarities are correct.

2. I'm not really sure what you mean by cartridge connector.

3. I inspected the motherboard thoroughly and for the life of me I can't find any broken traces.. I'm not an expert though. I could send some pictures if that would help. I have a decent camera and I could upload some high res photos.

 

2: Measuring the voltage at the cartridge port, basically. It is just an easy way to check your power input to the cartridge. Without a cart in the port, you can measure the voltage with a multimeter. It is an easy way to check the power in the SNES "down the line" from the voltage regulator without opening the SNES (even though you already opened it).

3: You did it visually? Did you use a multimeter to verify continuity for the traces?

 

2. Oh.. I get it. I'm getting 5V, from what I'm reading that's the correct value right?

3. I inspected it visually. Do I have to follow each trace visually and meassure it from there or is there some noob friendly schematic that I can follow? My multimeter doesen't have that beeping option to test continuity, so I just use the Ohm metter at 200 Ohm and get a reading, which is a major pain in the butt :/

 

Yep.

Really?? I am really surprised to hear this. Are you sure you don't have an option to toggle in on? My ohm/continuity testing doesn't have the tone on by default. There are some good SNES schematics out there that you can use as a guide to help you figure out where the various pins are going to go. Check this one - http://i.imgur.com/K8bfyx5.png

Also note that the CPU on those early units has been known to die, however it sounds like your unit is possibly just sick right now.

 

I'm halfway through checking continuity and I found something odd. According to the schematics CkRtech sent, pin 72 of the CPU should go to pin 6 of the WRAM, but I'm getting continuity from pin 73 instead, which in the schematics is empty. Maybe a revision difference? I have the SHVC-CPU-01