Unpredictable crashes with EverDrive N8 & early games - power draw issue?

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goldenband
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Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by goldenband »

tl;dr: My EverDrive N8 plays late games fine, but crashes on early releases. Is this a power draw issue? Can the issue be diagnosed from the symptoms I'm seeing?

I have an EverDrive N8, v1.3, made June 2013 (but bought December 2015). I expected to ditch my NES-001 for a Famicom, so I got the N8 in a Famicom form factor, but then I bought a Blinking Light Win and that brought my NES back to life. Consequently, my setup is EverDrive N8 v1.3 > KRIKzz Famicom to NES converter > Blinking Light Win > NES-001. Not pretty, I know.

My problem: when I play early releases -- Sky Kid, Gumshoe, Goonies II, Ring King, Urusei Yatsura: Lum no Wedding Bell -- they crash or reset sooner or later. I can go about 50-60 minutes in Sky Kid before I start to see crashes. Lum no Wedding Bell tends to crash sooner.

Meanwhile later games (Moon Crystal, Mitsume ga Tooru, Robocop 2 come to mind) are almost always fine, and I've had very long, crash-free sessions in games with no continues/passwords. Middle-era releases are usually OK. Original NES carts are fine.

Important data point: when I first boot up Sky Kid, I see a handful of what I think I've seen described as PPU dropouts -- momentary glitches, 1 scanline in height and about 8-10 pixels wide (rough guess). These show up as white lines on a black screen, and black lines on a light blue screen. After the first 10-15 seconds these dramatically decrease.

Is this likely to be a power draw issue? If so, is it caused by having an older model of EverDrive N8? Or is it an issue of failing caps or bad RAM in my NES? Or, somehow, the Famicom-to-NES adapter (doubt it) or the BLW (also doubt it)?

It's weird that newer games with more advanced mappers work fine -- almost makes me wonder whether games that use on-cart RAM are "safer" -- or maybe later games just had better error-handling routines.

Things I've tried:
  • Switching between a bunch of different power supplies: original AC, aftermarket AC, Sega Genesis PSU that supplies DC. Result: no change.
  • Moving from a house with sketchy, outdated electrical wiring, into one with much more modern wiring. Result: still getting crashes, though maybe the frequency has dropped. (But Sky Kid crashed on me today right before Level 25, after 45 min. of problem-free gameplay.)
  • Swearing, yelling, cursing. Result: blood pressure increase, no other changes.
Things I haven't tried:
  • Updating to the latest version of the EverDrive OS for my hardware. I ought to do this, but I doubt it's the cause.
  • Buying an EverDrive N8 Pro. If a newer hardware revision will fix this, I'm all for it, but I'm not made of money and no one will want to buy my 9+ year old v1.3.
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Memblers
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by Memblers »

My first suspect would be the FC-NES converter. Everdrive has 74LVC or LVT parts for level translation, these parts are much faster than the memory and logic of a normal cart. The signals are digital, but as more increasing length is added to increasing fast signal wires, there's a lot happening on the analog level, and we increasingly bump into physics, as signals may reflect, resonate, or the wire becomes a transmitting antenna.

Updating the OS is worth a shot, as it may affect timing for the signals. If updating it doesn't work, try downgrading to older versions.

New caps for the NES wouldn't hurt, I doubt it's the exact fix though. Interesting that you see an effect decrease after 10-15 seconds. Does make me imagine some kind of extremely marginal timing issue, the chip warms up it works a little better.

Why it would affect mapper zero, I have no idea though, that is strange.

Does your NES have the audio mod? I'm curious if you've tried Akamajou Densetsu on that setup, and what that sounds like. I also have an FC N8 but I use it with a Famicom, and the VRC6 audio in that game is there, but is extremely faint, and nearly inaudible.

One of the other common fixes for misbehaving NES bus, is series resistors. Something like 100 ~ 220 ohm resistors in series with the NES data bus. I've heard different theories as to why, bus conflicts or reflect signals, but either way, series resistors would dampen the effect. You would have to add those into the cart converter, but what a pain. (and to be clear, not a sure fix, in this case)
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aquasnake
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by aquasnake »

Early developed games, especially NROM and CNROM, saved a non gate in hardware of converting "cpu_ rw" to "/cpu_oe". It will cause a bus conflict when writing an address above $8000 (usually NROM should not have access to this, but some games will deliberately use this behavior). In case of bus conflict, the CPU usually wins the competition, but it is also possible that the PRG ROM output wins. Therefore, it is necessary to place the same data as the write registers on the specific addresses of the ROM, so that the two levels are the same.

If the ROM has been hacked, it is needed to look for blank data segments or invalid data segments to insert code, so the anti-conflict data might be modified, when a conflict comes, it will interfere with the data bus.

Well designed "/cpu_oe" generation circuit is the best method. Of course, resistors can also be connected in series between the data bus and the cart golden-fingers.
goldenband
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by goldenband »

Thanks so much, Memblers, for the helpful reply. Your explanation makes sense and no doubt I was too quick to dismiss the 60>72-pin converter as a possible culprit since, as you say, physics is a factor.

I'll try updating the OS and seeing what happens. I'm still dubious about the little fixed-width dropouts that happen on startup -- those scream to me "power issue". I could swear I remember reading commentary from someone who said as much, i.e. that the PPU will fail to render a certain predictable number of consecutive pixels in a scanline if there's a voltage issue.

After the big flash cart 5v vs. 3.3v scare of a few years back, I guess I keep wondering whether my older EverDrive N8 is simply drawing too much power, or otherwise causing PSU problems.

If the OS upgrade doesn't help, I guess my next step ought to be to buy an EverDrive N8 PRO and see if that puts paid to the issue once and for all. I suspect it will.

By the way, I don't have the expansion audio mod, sadly (I really should: wasn't there some sort of hardware device that could plug into the bottom of the NES to avoid the need for a mod?), and the ROMs I'm using are unhacked and match known good dumps.

Thanks again!
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Ben Boldt
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by Ben Boldt »

You might still consider getting a Famicom or AV Famicom. This would be a lot cheaper than a new Everdrive. Since you seem to be into the techy side of this stuff, it will probably come in handy to try various things on each system for comparisons. For example, if the everdrive does the same thing in a Famicom, you can eliminate your original NES console and the 72/60 pin adapter as the source of the problem.
calima
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by calima »

Also, the Pro version uses more power than the regular one.
goldenband
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by goldenband »

Ben Boldt wrote: Sat Jan 29, 2022 9:17 pm You might still consider getting a Famicom or AV Famicom. This would be a lot cheaper than a new Everdrive. Since you seem to be into the techy side of this stuff, it will probably come in handy to try various things on each system for comparisons. For example, if the everdrive does the same thing in a Famicom, you can eliminate your original NES console and the 72/60 pin adapter as the source of the problem.
Now that I look at the numbers, that's quite a good idea. Thanks for that -- I might well pick up an AV Famicom. (Almost bought an AV-modded Famicom a while back but waited too long to pull the trigger...)
calima wrote: Sun Jan 30, 2022 1:35 am Also, the Pro version uses more power than the regular one.
Oh jeez. :( Somehow I picked up the impression it had been re-engineered to reduce the power draw; guess not.
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Memblers
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Re: Unpredictable crashes with EverDrive N8 & early games - power draw issue?

Post by Memblers »

goldenband wrote: Sat Jan 29, 2022 6:37 pm By the way, I don't have the expansion audio mod, sadly (I really should: wasn't there some sort of hardware device that could plug into the bottom of the NES to avoid the need for a mod?), and the ROMs I'm using are unhacked and match known good dumps.
Yes, INL designed that audio expansion enabler. Last I checked, I don't think any of them are being sold individually yet, but they have been included as a pack-in with new releases that use expansion audio.
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