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PostPosted: Tue Apr 16, 2019 10:10 pm 
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Somewhat of a mystery what happened and what all broke, but when powering on with the 240p Test Suite on a modified cartridge, I have blown up my hi-def NES (USA front-loader). A sad day indeed. :cry:

I found that my NES RF box is providing voltage as intended, yet no power makes it to the NES 5V rails. Inspecting the Hi-Def NES board, I find that L8, right next to the main power input, is what blew. How could I go about finding the value of this part? It seems that it is there for the purpose of U10, which would provide clues to the L8 value. However, I have no idea what U10 is either. U10 seems to be a DC-DC converter in a QFN-16 package. It has this marking:

30012
77926
.505F

I know that L8 is what went bang though. If anyone has some secret schematics somewhere, I would love to know the specs of this inductor instead of making a wild guess.


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PostPosted: Wed Apr 17, 2019 11:17 am 
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I think I am going to stick in a 1 uH or less inductor tonight or tomorrow and see what happens. I like how the old one acted like a fuse, I worry I am going to put something too beefy in there now and something else harder to replace will blow next time.


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PostPosted: Wed Apr 17, 2019 12:31 pm 
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I know what I did wrong in the 240p cartridge now. I only used /ROMSEL to disable the PRG EEPROM, I did not disable it when CPR R/W = 0, so every time it was trying to do a bankswitch, it created a CPU data bus conflict. So it seems that the hi-def NES blows up when there is a bus conflict. I am not too impressed by that at all if that is true.


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PostPosted: Wed Apr 17, 2019 12:58 pm 
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No standard commercial discrete logic cart - neither licensed nor unlicensed - disables the ROM on bankswitching writes. And I'm confident tepples included a bus conflict prevention table anyway.

You might try PMing game-tech.us, or getting in contact with them in some other way.

As I understand it, the HDNES board is supposed to replace the original 5V regulator altogether, and it should take the unregulated ~+13V from the wall wart and - I thought - provides 5V back to the NES also.


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PostPosted: Wed Apr 17, 2019 1:38 pm 
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lidnariq wrote:
No standard commercial discrete logic cart - neither licensed nor unlicensed - disables the ROM on bankswitching writes. And I'm confident tepples included a bus conflict prevention table anyway.

You might try PMing game-tech.us, or getting in contact with them in some other way.

As I understand it, the HDNES board is supposed to replace the original 5V regulator altogether, and it should take the unregulated ~+13V from the wall wart and - I thought - provides 5V back to the NES also.

Oh wow, I always knew that some carts had the potential of bus conflicts, but I never knew that they were happening all the time... So I guess I still don't know why this blew up.

Sorry, I am a little frustrated atm, and still really searching for an explanation. I don't mean anything against the Hi-Def NES, it is a very awesome thing, and I do use it as one of my main machines. I do have my original 7805 disconnected and feeding in directly into the Hi-Def NES. Will try powering it up carefully with a current limited bench supply tonight when I put in the new inductor.

Edit:
So as long as during a bus conflict, you write the same value that is stored at that location in ROM, you should be okay? Is that the idea behind this?


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PostPosted: Wed Apr 17, 2019 4:10 pm 
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lidnariq wrote:
No standard commercial discrete logic cart - neither licensed nor unlicensed - disables the ROM on bankswitching writes.

Exceptions: ANROM has a circuit to disable ROM during writes, and AOROM uses mask ROMs with a +CE, which is connected to R/W.

I avoid bus conflicts in 240p Test Suite by overwriting the immediate value in the preceding load. Now I'm worried that I might have made a mistake. I'll probably have to figure out how to set up Mesen to break on bus conflict.

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PostPosted: Wed Apr 17, 2019 5:57 pm 
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tepples wrote:
lidnariq wrote:
No standard commercial discrete logic cart - neither licensed nor unlicensed - disables the ROM on bankswitching writes.

Exceptions: ANROM has a circuit to disable ROM during writes, and AOROM uses mask ROMs with a +CE, which is connected to R/W.

I avoid bus conflicts in 240p Test Suite by overwriting the immediate value in the preceding load. Now I'm worried that I might have made a mistake. I'll probably have to figure out how to set up Mesen to break on bus conflict.

My EEPROM had an extra /CE, so added a hex inverter and fed it /(CPU R/W) and it still has the sprite problem on my front loader with this modification. So at least we rule out bus conflict as potential source of the sprite thing.

I found a similar looking 1.5uH inductor and replaced the blown one on the Hi-Def NES board. I turned on my bench supply with voltage set to 0 and current limit set low. I then hooked it up to the bare Hi-Def NES power input and increased the voltage, which stayed at 0 due to current limit. I then increased the current limit slowly. It drew tons of current and the voltage stayed right at zero. So, something else is shorted on this board, and the inductor blew because of that short. Will see about investigating carefully with a thermal camera tomorrow, I bet it is that mystery QFN-16 chip... But I will try to determine exactly how far into the board the current flows this way.

I have always had the bottom of my RF box covered in capton tape for as long as I have had the Hi-Def NES mod in there, so I know that it did not short out to that. This is really a mystery what happened here.


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PostPosted: Thu Apr 18, 2019 9:16 am 
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I figured out that U10 is a TS30012 5.0V Buck Converter, package 16-QFN 3x3. Cheap and easy to replace!

https://www.digikey.com/product-detail/ ... ND/5456418

Later tonight I will try to figure out if that is what broke and possibly further speculations as to why.


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PostPosted: Thu Apr 18, 2019 10:07 am 
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It is very likely that my TS30012 is broken. I applied 1 Amp input for this capture. (My new inductor is rated 1 Amp.) Nothing warmed up after the TS30012. I will remove it and try applying 5 Volts to where its output is supposed to go.
Attachment:
IR_0076_2.jpg
IR_0076_2.jpg [ 115.58 KiB | Viewed 198 times ]


Edit:
The LED does turn on and blink like normal when I manually apply 5 Volts. Seriously considering putting in a 7805 at this point. ;) Still could be something blown up in the NES but I did not find a short on the 5V rail when I checked. Will be taking taking this 1 small step at a time.

Edit 2:
Reading through the TS30012 datasheet, it has "Cycle-by-cycle currrent limit with frequency foldback" and also "Full protection for over-temperature [...]". It also apparently has internal ESD protection. So this symptom could not likely be caused by any sort of short circuit or ESD, which also eliminates anything I might have screwed up in the 240p test suite cartridge, or the software itself, bus conflicts, etc, all eliminated. However, in the absolute maximum ratings of the TS30012, input to GND voltage range is -0.3 to 26.4V. This makes me wonder if my bridge has failed in the RF box and I am getting AC instead of DC. Or if somehow a negative charge built up on +13V rail. Will check for those things.


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PostPosted: Thu Apr 18, 2019 5:04 pm 
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I checked my RF box and the bridge rectifier is working fine. I hooked up DC +13V and DC -13V and both charged up the main cap positive. There were no bad connections or solder flash or conductive bits floating around. Kind of a dead end there.

Now I have the original 7805 hooked up, and feeding its 5 Volts directly to the Hi-Def NES board, but still not connecting the 5V to the RF box. I slowly turned it on, nothing crazy happened. With a cartridge inserted and HDMI cable not connected, the NES works normally out the composite AV jacks, with the usual 5-second delay that the Hi-Def NES has before it reverts to Composite mode. Sound and video are like usual in this mode. However, if I hook up an HDMI cable to my TV, the NES never starts and audio and video does NOT come out of the AV jacks... Normally there is modified "shadow" video coming out of composite in this mode. So the Hi-Def NES card is partially working, but something is still broken.

Since the LED can blink, and the 5-second timer works, we know that the FPGA and its ROM are at least partially working. It can sense whether or not I have an HDMI cable plugged in, but I am not sure what is involved for that to happen. I think that the next step is to probe the various power pins of the FPGA and the HDMI Transmitter chip and verify those voltages.

Edit:
the 1.8V and 1.2V linear regulators are both working. :\


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PostPosted: Fri Apr 19, 2019 4:17 am 
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Please read these pages first:
https://www.game-tech.us/hi-def-nes-faqs/
https://www.game-tech.us/hi-def-nes-ins ... on-guides/
https://www.game-tech.us/troubleshootin ... f-nes-kit/


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PostPosted: Fri Apr 19, 2019 9:19 am 
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Thanks! I did not know about the troubleshooting page. I read through that and realized that U11 and U8 are 2 more voltage regulators. These 2 are already working correctly though. All 5 of my voltage rails are good now:

5V -> U10 -> Broken, I removed it and am feeding 5V directly from the original 7805 into L6. 5V still disconnected from the RF box. Added 22uF Tantalum from R35 to GND for good measure.
3.3V -> U11 -> OK
2.5V -> U8 -> OK
1.8V -> U9 -> OK
1.2V -> U7 -> OK

I did not notice what the LED was doing when my HDMI cable is plugged in. I know that it was not blinking the same as it does without the HDMI cable. I will need to check that out. I also did not check my interposers. I had removed them in the process of debugging this, so it is possible that I damaged something while doing that. Will remove them again and check them out too.


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