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PostPosted: Mon Mar 05, 2018 4:16 pm 
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I have ordered custom carts from Aliexpress in the past for personal use, but they were always cheap EPROM+discrete based genuine NROMs and CNROMs. At least those were safe.

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PostPosted: Tue Mar 06, 2018 3:17 am 
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gauauu wrote:
I know (from experience) that that's what he does with GBA carts, so I wouldn't be surprised if that's what he does with NES carts also.

GBA is 3v though, so using 3v chips would not hurt the console; the biggest risk with those would be the cart itself failing due to bad quality, no?


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PostPosted: Tue Mar 06, 2018 8:15 am 
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calima wrote:
gauauu wrote:
I know (from experience) that that's what he does with GBA carts, so I wouldn't be surprised if that's what he does with NES carts also.

GBA is 3v though, so using 3v chips would not hurt the console; the biggest risk with those would be the cart itself failing due to bad quality, no?


Yeah, it's not problematic on the GBA the way it is on the NES. But just that since he's comfortable doing it for one system, that's likely what he does for others.

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PostPosted: Thu Mar 08, 2018 9:02 am 
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Thank you for alerting me about this game being dangerous. I've bought it quite a while ago but still haven't gotten around to actually playing it (as a kid, I never imagined I'd ever buy more NES cartridges than I had time to play). So guess it looks like I will make sure to dump it first and never run the original board in my NESes.

Out of curiosity, I did open my version, and it looks just slightly different.

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But I'm guessing it's having the same problem with missing level translation?

Ironically, Dorke & Ymp - the other cartridge I bought from Piko at the same time as Quest Forge - I also needed to get a dump for, but for a different reason: The game is very frustrating and only gives passwords when worlds are completed. So when the game suddenly crashed with a garbage screen near the end of world 2, I just didn't wanna replay it all.

When contacting Piko about it, Eli blamed my SNES console, saying the game was "bug free", and wouldn't provide me a dump. So after creating a post about how to dump it myself on this forum, Eli sent me a mail about how a "post like that can get you and the forum in trouble".

But my post was successful in that I learnt I could get a dump just by paying an additional $5 to download the game on Steam. So a "happy" ending to it all. But I actually haven't played the game since. Getting threats like that - as a paying customer who's just trying to work around a pretty bad game bug - left me with a sour taste that I've rarely experienced in the homebrew community.

Anyway, bit of a rant here, but point is I personally wouldn't give Piko the benefit of doubt about knowingly using dangerous components to cut costs, seeing how Piko treats customers. And while I realize that some precious lost games can only be obtained from Piko, I would recommend people to stay away from dealing with Piko when there are alternatives.


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PostPosted: Thu Mar 08, 2018 11:18 am 
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Bananmos wrote:
But I'm guessing it's having the same problem with missing level translation?


Yes. All the board appears to do is try to convert the 5V power supply to 3V for powering the 3V parts. It doesn't account for the different voltage levels of all signals like address and data lines.


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PostPosted: Thu Mar 08, 2018 11:28 am 
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Bananmos wrote:
I personally wouldn't give Piko the benefit of doubt about knowingly using dangerous components to cut costs ...

Crazy thing about it is the parts on those boards is significantly more expensive than if they would have used 5v parts (2x 1Mbit roms trimmed to NROM256). But I assume the Chinese already have those multicart boards in large volumes so it's cheaper/easier for them to use the boards on the shelf instead of designing a dedicated 5volt NROM (and/or discrete logic mapper) cartridge.

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PostPosted: Mon Mar 12, 2018 9:12 am 
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Hi all - Derek from Gradual Games pointed me to this thread via NintendoAge and I wanted to post a picture of the board that I just got when my game arrived today. Looks like it's basically the same as the earlier board. I'll let the hardware experts have at it though.

Thanks,
Mike


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File comment: The board I received today (3/12/2018)
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PostPosted: Mon Mar 12, 2018 9:37 am 
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Xelius wrote:
Looks like it's basically the same as the earlier board.


Yes it's basically the same non 5v tolerant design. I still haven't got any info on the shipping of the copy I just bought, but I'm starting to loose hope that changes were made with the recent batch..

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PostPosted: Mon Mar 12, 2018 9:41 am 
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I guess one way to use these boards would be to build an adapter akin to an fc-nes adapter or game genie, with a proper 5v -> 3.3v level shifter, but ugh

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PostPosted: Mon Mar 12, 2018 9:53 am 
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My recommendation would be to simply play them on a cheap clone as it will likely be running at 3v itself. The fact that clones typically run near 3v may be part of the reason the Chinese designs don't bother with 5v tolerance.

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PostPosted: Mon Mar 12, 2018 10:19 am 
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It is under my understanding that the voltage regulator (U7) on the PCB would shelter the PCB from any damage. I don't think the PCB would cause any damage to the console, since the console is the one with higher voltage.

I test all our games my self, beta test that is, so I have to play through them for hours on both NES NTSC and PAL consoles (I don't care about clones, most are fine with exception of Retron 5).

Im not a hardware engineer, the factory we used is not the one directly selling bootlegs on Aliexpress, they serve all china, taiwan, and hong kong. And are the only ones that really give quality components and gold pins on PCBs (thus why Retrobit uses them) The guy that designs has been an electronics engineer for over 40 years and has developed games for NES and Genesis. He has done clone consoles, NOACs, and now he is working on clone consoles with upscalers He is pretty smart and we trusted his judgement, on top of that we tested the PCB to work.

It is a shame that he does sell the PCBs to other trade companies in china that do bootlegs but oh well, we just buy the PCBs, and cannot control anything else. We might be moving to get the games done by other company that has done legit hardware products sold world wide; we'll see how it goes.

We'll look into this issue and stress test to see if the PCB causes any damages to the console or to itself by being played on the console.

Also, I am going to reach out to Kevtris to see if he can put the rumors to sleep about the whole 5v >3.3V chips killing retro consoles.

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PostPosted: Mon Mar 12, 2018 11:39 am 
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piko wrote:
I Don't think the PCB would cause any damage to the console, since the console is the one with higher voltage.


That's unfortunately not how it works. If you feed a 5v data signal into a 3.3v device, you have excess voltage. To protect the 3.3v device (from ESD spikes), you have clamping diodes, and if done right, a level shifter (for continous excess voltage. not just on the power line but on the data lines as well). However if the latter is not present, a data high means the clamping diodes will dump the excess to the 3.3v-gnd line just like it would dump an ESD. Unlike ESD, this happens frequently which means you have a more or less continous excess. This demands excessive current output on all logic outputs, console-side, everytime it outputs a high. This draw of current is well outside specs and it is probably the explanation to reports of dead consoles as a result of using pirate multicarts of the particular design that is being debated.

Cartridge-side, this will cause excess heat on any clamping diodes used. I'm not too worried (note: i'm a layman) about diodes not being designed for continous conduction simply because they're used this way in control voltage circuits of comparable voltages without deteriorating (i've never seen a diode fail this way). I think it's more important to be on the lookout if the excess heat is within specs of the diode/other affected components or not. But anyway...

edit: edited in hopes of better clarity.

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Last edited by FrankenGraphics on Mon Mar 12, 2018 12:33 pm, edited 6 times in total.

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PostPosted: Mon Mar 12, 2018 11:49 am 
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To be clear, trying to start an argument here. I'm simply trying to educate and provide the easily obtainable facts that aren't really subject to interpretation. It's very clear the datasheet specs are being violated.

MX29LV160ABTC datasheet

I've attached page 21 Absolute Maximum ratings spells it out pretty clearly. The design exceeds the 3.3v + 0.5v = 3.8v maximum rating by ~1 volt when connected to original 5v consoles. As the datasheet notes this can cause permanent damage to the device. The permanent damage results from the high current condition that's created on the pin's ESD diode this is the effective circuit:

5v placed on flash pin ---|>---- 3.3v flash chip internal supply.

This forces a 1.7volt differential across that ESD diode which will result in a high current condition as it greatly exceeds the typical 0.7v forward biased voltage drop. This is precisely why the absolute spec in the datasheet is listed as Vcc + 0.5v to keep the ESD diode from turning on. Note 1 in the datasheet lets you exceed the Vcc+0.5v spec but only for a very short period of time 20nsec which isn't long enough for the diode to conduct a significant amount of current assuming that was even enough time to turn on.

Now in the case of putting this flash chip directly on the NES's CPU bus, you won't actually ever get the flash chip's i/o pins to 5v. The 5v CPU, PPU, & memories on the main board will try all they can to drive their outputs to 5v, but once the 3.3v chip's ESD diode turns on ~4v the console's drivers won't be able to drive the voltage any higher. They will try as hard as they can which equates to sourcing as much current into that line as possible. That high current is a load all the chips in your console weren't designed to supply, it results in heat which will only make the problem worse. Sure, maybe exceeding these ratings will never result in damage to your console. But it's a significant risk and burden I would rather not put on my beloved consoles, nor expect others to do without their consent.

Quote:
It is under my understanding that the voltage regulator (U7) on the PCB would shelter the PCB from any damage.
The funny thing is if you instead removed that regulator and supplied the flash chip directly with 5v it would remove all of these burdens from the console's chip set. It would clearly be violating the flash chip's Vcc specs, but this is mostly only concern for the flash chip which I care much less about than the chip set in my console. The flash chip supplied with 5v will obviously consume more current than when supplied with 3.3v, but without measuring it, I would guess it's insignificant compared to loads we typically ask of our console's power supply.


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PostPosted: Mon Mar 12, 2018 12:02 pm 
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infiniteNESlives wrote:
The funny thing is if you instead removed that regulator and supplied the flash chip directly with 5v it would remove all of these burdens from the console's chip set.


Fwiw, the sram on the photographed mindkids boards is actually rated to tolerate both 3.3v and 5v on all its pins (2.4-5.5v)

Part number: BS62LV2001

Current consumption:
Code:
Vcc = 3.0V C-grade : 20mA (Max.) operating current
I- grade : 25mA (Max.) operating current
0.1uA (Typ.) CMOS standby current
Vcc = 5.0V C-grade : 35mA (Max.) operating current
I- grade : 40mA (Max.) operating current
0.6uA (Typ.) CMOS standby current


edit: typo - sram not srom

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Last edited by FrankenGraphics on Mon Mar 12, 2018 12:11 pm, edited 3 times in total.

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PostPosted: Mon Mar 12, 2018 12:09 pm 
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Quote:
Fwiw, the srom on the photographed mindkids board is actually rated to tolerate both 3.3v and 5v on all its pins (2.4-5.5v)

Yes, assuming it's supply is powered with 5v. IDK what supply the SRAMs use on the design. If they supply them with 3.3v then it's the same story/problem as the flash.

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