I'm new to soldering, only about 1 year or so doing basic stuff. Seeing this in real time def helps me learn to be more patient instead of stone handed Neanderthal.
Sorry for all the trouble this board gave you, but this video turned out awesome because of it! I really admire your perseverance. The SNES I fixed just had a bad CPU which luckily was my first guess as consensus seems it's by far the most likely chip to be bad. But, just needing to replace that one chip had me getting discouraged, as I didn't have a parts board and didn't know how to confirm that was definitely the bad chip before buying a parts board via eBay. I'd also never done any hot air work before that project. But, when the board worked fine afterward, I was pumped as well! I hope more information can be confirmed about the Field flag test in the diagnostic cartridge. It would be good if all of those tests were well documented somewhere. Thanks again for a great repair video, and yes, I'd love to see more repair videos on SNES and NES, please.
Hell yeah! Congrats on fixing yours, now you need to find some more and fix them. And yes, there will be more SNES repairs coming, no NES ones yet as it seems all of mine just work, how annoying!
I'm worried about my old computer & retro game stuff. I recently lost (no longer work) 2 rubber key Spectrums & a CRT. Now I'm worried about my SNES!! Thanks! D:
Pls help me, I just bought a snes pal eu and as for example when I start DKC it starts as normal with the Rare logo but then poof no image. no image, can't use the controller but I still hear the music.
Another amazing video, Mark! Kudos to you and your perseverance with a great sense of humor. There are multiple lessons in this video for most of us to learn. 👏🎉
I suppose the good news for me is that I don't need to replace any of these chips. I used a burn in cart on my Super Famicom and it passes all tests. Gonna have to open it up and check on the caps.
Nice fix. Thankfully the problem with my thrift store NES was a damaged trace on the board. Noticed a bodge wire where someone had cut IRQ and then bridged the cut. They didn’t realise they damaged the next trace. I put in another wire to bridge that and it booted right up.
Interesting, the SNES I have also got problems, but it can run Mega Man X and Mario Kart just fine. The problem is it freezes up the moment it reaches the world map part of Super Mario World. I bought another Super Mario World to test if it was the game, but now both Mario Worlds crash at the same part. :)
This was likely a SHVC-CPU 01 board. Those boards are junk and super prone to CPU failure. If you're gonna buy one you should skip that board revision since they're all timebombs and replacement parts require a donor SNES
@@playstation2bigs I believe those ones are more reliable in terms of the CPU not dying on them. I had a SHVC-CPU-01 I recapped to try and prolong it's life and after 25 years of service the CPU died on it and I had to landfill it sadly the shell was already brittle and partly broke from age. I still got a SNES jr. that I should RGB amp mod
@@oOignignoktOo1 i also have that 1st gen shvc-cpu-01 japan version from japan. Last year it was working fine, put to storage, this 2024 i fire it up the screen color is dull and wash out then i open it up replace the 6 capacitors near the AV multi out, then power it on to my surprise the screen turns blank or black but there's a game sound. I believe the old capacitor is not the problem but the cpu or the two ppu.
Both PPUs have a pin labeled "FIELD" and he looked at both with a scope (they are connected electrically, so the field signal was identical as expected). But I have a sneaking suspicion that "field flag" and field pin are 2 different things.
Oh man, I've made it to the bigtime! Thanks for the shout out. I just found your channel a few months ago and enjoy it. No nonsense, all about the repairs! I love it.
Since those FIELD pins only seem to connect to each other, it's apparent that's not what's meant by "FIELD FLAG". I bet it has something to do with HBLANK or VBLANK coming from the PPU to the CPU.
Something I edited out was checking those HBLANK and VBLANK pins, along with a few others. They showed 15.7khz and 60hz so I didn't bother going into that. My thoughts are the field flag has something to do with showing progressive or interlaced. The SNES can do both and the 240p test suite is an easy way to swap between them. Unfortunately it wouldn't boot the 240p test suite so I couldn't confirm that. You might have noticed the recent games list on the everdrive is in a different order later in the video from me trying to load up a bunch of different stuff off camera. I haven't been able to confirm it but I'm guessing PPU2 is responsible for switching between 240p and 480i and this is supposed to be reported back to the CPU. If PPU2 doesn't do this as expected or fails to report the correct information back to the CPU, then the field flag has failed to be set.
@@TheRetroChannel So that sounds correct. Well, I looked into the PPU's internal registers from the official docs I found on the Internet Archive and found a software-readable field flag. Since the display output is interlaced, there are 2 fields per frame. The field flag indicates which field it's currently doing -- even lines or odd lines. It's possible that the faulty PPU was only repeating the same frame.
PPU2 generates all clocks, syncs, resets, and makes a video signal from the bitplane data. It contains the DAC and palette registers. Encoder effects like transparency are done there. You can see on the schematic that only the data lines from the VRAM go to PPU2, as the control signals from PPU1 tell it what kind of data is on the bus. PPU1 handles object and map generation, VRAM refresh and access by the CPU, and Mode 7 transformation... basically everything that would affect how graphics data comes out VRAM. The CPU also contains the HDMA/DMA engines and I/O ports, along with all memory region and chip select logic. If you're familiar with the Amiga, PPU2 is exactly like Denise and PPU1 is most of Agnus with the rest being in the CPU. As far as troubleshooting goes, when you see pixel-width glitches or clock/sync related stuff (like the FIELD flag) it's gonna be PPU2. The FIELD signal comes from PPU2 and is used by PPU1 to know if it should generate the even or odd field in interlace mode. The field flag is just a bit in a PPU register. The failure is because the test is setting interlace mode (you see the converter lose sync when it does) but it never sees the flag change.
