Blown up Hi-Def NES board

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krzysiobal
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Re: Blown up Hi-Def NES board

Post by krzysiobal » Wed Apr 24, 2019 5:04 am

I was experimenting one day with replacing regular 7805 with a step-down one based on LM2596. Unfortunately, I forgot to solder one leg of the output capacitor. As a result (this is just my suspicion) - output voltage has risen very quickly over 5V before the feedback loop of this chip could react and it burned my PPU.
Since that time I am sceptic to non-linear regulators, especially that when I soldered the cap correctly and replaced PPU, i found out a little horizontal bars in the video which were not present when I replaced it with 7805 - probably the 100kHz switching freuqency adds significant noise.

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Fri May 10, 2019 1:37 pm

It turns out the level shifters I have are similar but actually different, so I am not able to replace them... Not sure where to go next with this. It would be great if I could eliminate the CPU interposer card somehow. Right now I do not know if there is something wrong with the main board or with the interposer. It seems unlikely that this is the PPU interposer but still not impossible I guess.

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Fri Jul 26, 2019 4:57 pm

FINALLY I got back to this. I replaced all 5 of the level shifter ICs. It had no effect at all. When running without an HDMI cable attached, it still works fine through the composite. When attaching the HDMI cable, it still hangs with dim LED. Not sure what to try next!

I know that all of my power supply voltages are good from the FAQ, and also I plugged the same HDMI cable into my Xbox 360 to verify the HDMI cable and the TV. That was all good. The only possible things remaining that I can tell:
  • Additional logic on each interposer card (best case scenario)
  • FPGA (hopefully not because it's expensive)
  • AD9889B HDMI chip (Hopefully not because it is obsolete now, hard to find)
  • The flash chip that runs the FPGA (seems doubtful)

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Wed Aug 14, 2019 10:11 am

My theory is that 1 of 2 things happened:

- The 5V regulator shorted itself out somehow (which is hard to explain.) This blew up the little inductor, which generated a high-voltage spike, which broke something else that I have not found yet.

or

- Something drew lots of current, which blew the little inductor, which generated a high-voltage spike, and the spike is what wiped out the 5V regulator and broke something else that I have not found yet. Whatever drew lots of current no longer does that once getting the 5V repaired (which is also hard to explain).

From what I can tell, the Hi-Def NES has no protection for bus conflicts, which theoretically should be okay, and theoretically is the same as a normal NES... These level shifters are modern though, and they may be more sensitive or drive more current or something. It seems a little far-fetched to me that this caused enough current to blow up that inductor, especially because the same cartridge that was in there doesn't break a normal NES (other than sprite artifacts) and replacing the level shifters had no effect.

Given the fact that there is a web page posted with instructions what to do if this inductor explodes, it must be a common problem. Do we have any idea the root cause of this inductor problem when it happened to everyone else?

Uffawa
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Re: Blown up Hi-Def NES board

Post by Uffawa » Mon Feb 03, 2020 2:18 pm

Reviving this, sorry! Same thing happened to me yesterday. I had just finished install and tested with an ever drive n8, used the NES test cart rom and a scrolling rom etc. everything was great. Put it together, tested once more with duck hunt and it was fine so I shut it off and didn’t touch it for a day (this was saturday). Sunday I decided to play some games but had no power. Took it apart and found L8 (R100) as a big old hole in it. U10 seems to be shot, L7 isn’t shorted to ground though, so I’ll need to se if I can remove R35 and power with the 7805. Super weird.

Mine was on a top-loader. Oof.

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Mon Feb 03, 2020 6:37 pm

So sorry to hear that. I went through a lot of pain and anguish losing my Hi-Def NES, I tried a lot of things to fix it except I never replaced these 3 components:

- FPGA (expensive, may be hard to remove the old one without burning/bubbling the board)
- HDMI chip (unobtanium? QFN package, so hard to attach replacement)
- FPGA's flash chip (might be easy, but not a very likely suspect though)

I would love to fix it but need guidance to proceed, and I fear that won't be happening because nobody really knows what goes wrong with these things or what to try next. It seems caused by a short circuit somewhere, which blows the inductor, which creates a voltage spike, which wipes out other stuff. I would say that the inductor should at least be sized to survive current limit mode of the 5V regulator. But as far as whatever draws loads of current in the first place, nobody knows, so nobody knows how to prevent it. Since there isn't a schematic or BOM available, I suppose it is possible the inductor is not rated for a normal amount of current. What little I know about this circuit, the 5V regulator + inductor seem to be a 5V buck converter. Maybe the peak currents are too high for the inductor. Speculation only.

It is possible that yours is fixable just by removing R35 as you say. That did not work for me unfortunately and I am still quite sad and disturbed over it. If I was to fix it, I would be scared to use it again, so that limits how far I am willing to go to fix it.

lidnariq
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Re: Blown up Hi-Def NES board

Post by lidnariq » Mon Feb 03, 2020 7:19 pm

The HDMI chip is probably unidirectional, just accepting the clocked data from the FPGA. If so, it should be easy enough to find a parallel bus between the FPGA and the HDMI sender and see if data is being sent via it.

Uffawa
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Re: Blown up Hi-Def NES board

Post by Uffawa » Mon Feb 03, 2020 7:23 pm

Ben Boldt wrote:
Mon Feb 03, 2020 6:37 pm
So sorry to hear that. I went through a lot of pain and anguish losing my Hi-Def NES, I tried a lot of things to fix it except I never replaced these 3 components:

- FPGA (expensive, may be hard to remove the old one without burning/bubbling the board)
- HDMI chip (unobtanium? QFN package, so hard to attach replacement)
- FPGA's flash chip (might be easy, but not a very likely suspect though)

I would love to fix it but need guidance to proceed, and I fear that won't be happening because nobody really knows what goes wrong with these things or what to try next. It seems caused by a short circuit somewhere, which blows the inductor, which creates a voltage spike, which wipes out other stuff. I would say that the inductor should at least be sized to survive current limit mode of the 5V regulator. But as far as whatever draws loads of current in the first place, nobody knows, so nobody knows how to prevent it. Since there isn't a schematic or BOM available, I suppose it is possible the inductor is not rated for a normal amount of current. What little I know about this circuit, the 5V regulator + inductor seem to be a 5V buck converter. Maybe the peak currents are too high for the inductor. Speculation only.

It is possible that yours is fixable just by removing R35 as you say. That did not work for me unfortunately and I am still quite sad and disturbed over it. If I was to fix it, I would be scared to use it again, so that limits how far I am willing to go to fix it.

Well rats! I’m bummed, as you are. I really love my hidefnes and really don’t expect top tier support as it’s a “home brew” product so I was just hoping I could remedy it. I’ll update this thread with my findings later but I’m not even close to as knowledgeable in the world of EE as yourself so I’ll be sticking to the basics. Fingers crossed! I may bite the bullet and just buy another board, but we’ll see.

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Tue Feb 04, 2020 12:08 am

The guy is actually really helpful, he even came here and replied to this thread. I think the Hi-Def NES a great thing but until this problem can be understood and prevented/fixed, I couldn't recommend getting another one.

If I was going to spend money on this sort of thing again, I would get NESRGB from Tim Worthington, then make an RGB SCART cable for it and feed it into my SCART-to-HDMI adapter. This would not be as good of quality or have any of the cool features of the HiDefNES though.

Uffawa
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Re: Blown up Hi-Def NES board

Post by Uffawa » Tue Feb 04, 2020 7:44 am

Ben Boldt wrote:
Tue Feb 04, 2020 12:08 am
The guy is actually really helpful, he even came here and replied to this thread. I think the Hi-Def NES a great thing but until this problem can be understood and prevented/fixed, I couldn't recommend getting another one.

If I was going to spend money on this sort of thing again, I would get NESRGB from Tim Worthington, then make an RGB SCART cable for it and feed it into my SCART-to-HDMI adapter. This would not be as good of quality or have any of the cool features of the HiDefNES though.
That's a good point. I have a framemeister, so it'd be as good as it can be without true HDMI output, I'd think.

Here's to hoping a new rev fixes it! :beer:

Uffawa
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Re: Blown up Hi-Def NES board

Post by Uffawa » Sat Feb 22, 2020 5:50 pm

Small update on this. I got a reworking station and replaced the R100 and the 5v reg, the board now powers back on! It’s progress, and I’m pretty happy about it since it’s my first undertaking of reworking SMD. Anyway, the power doesn’t seem to hold very steady and the NES eventually turns off, as does the HDN. I’m thinking it’s the 3v reg, but I need to rest with the 7805 to make sure it at least works. I’m worried something else may he going on because I found a small solder ball on the board — I’m hoping it’s just a stray piece of solder and not from the HDN. I’ll update when I have more info.

Edit: really weird update. Connected with the 7805 and it works, but only if I have the power button depressed (front loader) and then plug it in. Otherwise, no go. So it seems it’s still kind of working, but something is obviously off. Anyway — that’s all I have for now.

Uffawa
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Re: Blown up Hi-Def NES board

Post by Uffawa » Sun Aug 16, 2020 10:32 pm

I’m back! Got a 3.3v regulator replacement and it’s fixed! It’s alive! http://d.digikey.com/dc/KnEa49LIxePFwHl ... sTiX00E30U

lidnariq
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Re: Blown up Hi-Def NES board

Post by lidnariq » Sun Aug 16, 2020 11:01 pm

Congrats!

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Ben Boldt
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Re: Blown up Hi-Def NES board

Post by Ben Boldt » Mon Aug 17, 2020 9:25 pm

LUCKY! :beer:

I wish I could fix mine.

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