SNES Partially Loads Game

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Ms. Ziggie
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SNES Partially Loads Game

Post by Ms. Ziggie » Thu Oct 31, 2019 1:52 pm

Hello!!

I’ve been trying to get my SNES to work all day. I haven’t used it in some years, but I’ve been it’s only owner. It’s the original SNES the fatty version.

Basically, when everything is connected it loads the game but only to the start menu, if you hit start it cycles to No Signal and then back to the start screen. If just left alone, it basically loops the start menu over and over again.

So far all I have been able to rule out are the cables as it does the same thing with both sets of AV cables I have, one HDMI adapter and the N64 Multi-out to composite. I don’t have another game here to test it with. I also don’t have a game bit so I have not been able to take either apart to further inspect them.

I’m wondering if anyone can help narrow me down to Cart or Console so I can target my troubleshooting a little bit better.

I really appreciate it. I’ve been all over the internet today trying to find troubleshooting and haven’t found anyone with the same issue documented... that’s how I found this place and some wonderful information but nothing quite fits.

Thanks and have a great day!!

lidnariq
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Re: SNES Partially Loads Game

Post by lidnariq » Thu Oct 31, 2019 2:25 pm

Ms. Ziggie wrote:Basically, when everything is connected it loads the game but only to the start menu, if you hit start it cycles to No Signal and then back to the start screen.
"no signal" implies something is causing the SNES to reset.

What specific cartridge are you playing with?

Ms. Ziggie
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Re: SNES Partially Loads Game

Post by Ms. Ziggie » Thu Oct 31, 2019 2:44 pm

lidnariq wrote:
Ms. Ziggie wrote:Basically, when everything is connected it loads the game but only to the start menu, if you hit start it cycles to No Signal and then back to the start screen.
"no signal" implies something is causing the SNES to reset.

What specific cartridge are you playing with?
Super Mario All Stars + Super Mario World

lidnariq
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Re: SNES Partially Loads Game

Post by lidnariq » Thu Oct 31, 2019 2:54 pm

And all five games (SMB1, SMB2j, SMB2, SMB3, SMW) all crash in the same way?

Are you in PAL-land or USA-land?

Ms. Ziggie
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Re: SNES Partially Loads Game

Post by Ms. Ziggie » Thu Oct 31, 2019 2:58 pm

lidnariq wrote:And all five games (SMB1, SMB2j, SMB2, SMB3, SMW) all crash in the same way?

Are you in PAL-land or USA-land?
USA Land with the USA console.

lidnariq
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Re: SNES Partially Loads Game

Post by lidnariq » Thu Oct 31, 2019 3:11 pm

... My best hunch is that the problem is your SNES, and the SNES needs its capacitors replaced. But ... that's only a hunch.

Ms. Ziggie
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Re: SNES Partially Loads Game

Post by Ms. Ziggie » Fri Nov 01, 2019 7:35 pm

So...

Sacrificed a flathead screwdriver into a makeshift tool and got the SNES open. The 62 pin connector’s screw tabs are black plastic instead of metal. It’s different than every tear down guide and video I’ve seen, which wasn’t too concerning until I couldn’t get it to release from the board. Did some cleaning, as much as I could without removing that piece, but no change in performance.

I also got several other test games, and they’re all doing the same thing. Power -> Reset. Some manage to get to the title screen, others just a black screen -> no signal.

I mean, the inside and the board looks super clean like I just can’t see any other issues.

Any idea how to get the pin connector out with the black plastic tabs??

lidnariq
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Re: SNES Partially Loads Game

Post by lidnariq » Fri Nov 01, 2019 8:05 pm

I don't think you need to remove the connector - if the connector were what were bad, you SNES would do one of:
1- Never generate a valid signal (CIC failure)
2- Always generate a valid signal (CPU crash)

But because you get both behaviors, and especially because it recovers on its own, without you doing anything more than pressing buttons on the joystick, it has to be something else. That's why my hunch is that you need to replace the capacitors inside - that's one of the very few things that would cause the symptoms you've reported.

krzysiobal
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Re: SNES Partially Loads Game

Post by krzysiobal » Sat Nov 02, 2019 12:50 am

->Check if the power supply is OK.
*Powering my SNES using 12V 1.3A DC makes it behave weird - sometimes after a few minutes the console just resets or power downs and then cannot be turned on for next few seconds. Either some thermal protection inside power supply or the rectifier bridge in SNES cannot withstand constant DC current (when passing AC - all four diodes work and the heat is equally spreaded over them, while in DC mode - only two conduct current)

->Check the console using one of the test ROMs: https://tcrf.net/SNES_Test_Program (Needs LOROM PCB)

->Try to clean the cartridge connector from oxidation or dust by insterting and removing the cartridge around 30 times (without powering console)

Ms. Ziggie
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Re: SNES Partially Loads Game

Post by Ms. Ziggie » Fri Nov 08, 2019 4:46 pm

lidnariq wrote:I don't think you need to remove the connector - if the connector were what were bad, you SNES would do one of:
1- Never generate a valid signal (CIC failure)
2- Always generate a valid signal (CPU crash)

But because you get both behaviors, and especially because it recovers on its own, without you doing anything more than pressing buttons on the joystick, it has to be something else. That's why my hunch is that you need to replace the capacitors inside - that's one of the very few things that would cause the symptoms you've reported.
Update.

Replaced the caps tonight. Same exact thing happening.
Power up, intro cuts out, boot cycles, repeat.

krzysiobal wrote:->Check if the power supply is OK.
*Powering my SNES using 12V 1.3A DC makes it behave weird - sometimes after a few minutes the console just resets or power downs and then cannot be turned on for next few seconds. Either some thermal protection inside power supply or the rectifier bridge in SNES cannot withstand constant DC current (when passing AC - all four diodes work and the heat is equally spreaded over them, while in DC mode - only two conduct current)

->Check the console using one of the test ROMs: https://tcrf.net/SNES_Test_Program (Needs LOROM PCB)

->Try to clean the cartridge connector from oxidation or dust by insterting and removing the cartridge around 30 times (without powering console)
Tested power supply, tested bad. Replaced power supply, no change.

So at this point:

Verified it’s not the cartridge
Cleaned the cartridge connector in console
Replaced the power supply
Replaced caps

Is there anything else worth trying?

lidnariq
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Location: Seattle

Re: SNES Partially Loads Game

Post by lidnariq » Fri Nov 08, 2019 4:56 pm

.... maybe replace the 7805? the fuse? the power switch assembly?

nocash
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Re: SNES Partially Loads Game

Post by nocash » Fri Nov 08, 2019 10:04 pm

Measure the 5V with oscilloscope or multimeter.
And check for broken solder pads.

Maybe also try to measure the Reset pin, to see if it does really reset (or just happens to jump to the entrypoint without reset).

Apart from power-failures, I think the only reset source would be the CIC? So you could disable the CIC.

Or is the console already modded with CIC disable, or even with PAL/NTSC mode switch? Some games refuse such mods.

With the title screen working, it must later on use some other hardware component that doesn't work... whatever, a different video mode or audio... or just a higher memory address on the cartridge address bus. In so far, a dirty connector pin could cause such problems (well, except, I guess it might rather crash/hang instead of successfully rebooting in such cases).
homepage - patreon - you can think of a bit as a bottle that is either half full or half empty

Markfrizb
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Location: East Texas

Re: SNES Partially Loads Game

Post by Markfrizb » Tue Nov 12, 2019 3:36 pm

Super Mario All Stars has sram detection and it could be that the SRAM in the cart is bad..... Hence, the black screen. SMWAS won't even boot if it doesn't see sram on the cart...

Maybe it's that??

Edit: maybe not after reading more of the posts.... :/

Ms. Ziggie
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Re: SNES Partially Loads Game

Post by Ms. Ziggie » Fri Nov 15, 2019 3:45 pm

Replaced motherboard.

Problem solved

Thanks guys!

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