Hi-Def NES Reversed Polarity

[MNiceGuy]

This weekend I finished my remaining Hi-Def NES Toploader. Everything went smooth but when I powered on the system nothing happened. No light from the Hi-Def NES board, no image on the screen, nothing.

 

When I inspected the install I found that I had the V and GND leads to the Hi-Def board in the opposite positions. In other words, I had polarity reversed.

 

I corrected my mistake and now everything seems to be working great. I tested the system for 4-6 hours and it seems to be stable and free of graphical anomalies.

 

Since I would like to sell this system, I am wondering if there is a potential that I have done harm which just hasn't manifested itself yet. Ideally, the Hi-Def NES board's power regulation hardware would have protection against reversed polarity but I can't seem to find any specific information on it.

 

Am I in the clear or should I be wary of passing this one along?

Edited July 23, 2018 by MNiceGuy

[+-^CrossBow^-]

I haven't looked at the specifics on the Hi-DEF NES either, but it would surprise me if Kevtris didn't put a diode in there to protect against that. And since you corrected it and it seems to be working normally, I would just put a game in and let it run through its demo mode etc. for a few hours and make sure.

 

I see that you basically did that already. It is likely fine then as any real issues would show up, especially once the Hi-DEF NES starts to get hot. Or at least mine does...and I've never like that but ehh seems to work fine.

[mobiusstriptech]

Kevtris did not put anything on the board to prevent backwards polarity. You are extremely lucky. These boards are very very susceptible to damage from reverse polarity. At this point I have replaced 5 boards for issues with reversed polarity or just deciding to pop for unknown reasons.

 

When they pop, and it is a literal pop sound, U11 tends to blow internally. I have also seen other regulators blow from the same thing.

[+-^CrossBow^-]

Wow, that surprises me with all the other tech in it that even something like this isn't present on the Hi-DEF NES. Especially given the cost for them as well. Luckily the onboard regulator isn't required as you can bridge a couple points on the Hi-DEF Nes board and go back to using the 7805 to provide all the power needs.

 

My only real concern with the Hi-DEF NES has been the amount of heat it gives off! I've checked and checked mine all over and the HDMI out chip seems to get really warm on these. Surprises me they recommend using weather stripping foam ontop of that very chip in the top loader as an insulator barrier.

[mobiusstriptech]

Yeah I don't know why he didn't add something. Personally I would go the mosfet route over the diode, just because you don't have a voltage drop to contend with. The biggest downside though is currently, if U11 pops, you have a very high chance of damage elsewhere. If that happens then the 7805 bypass won't work. Of the ones I have dealt with, I have never been able to use the 7805 bypass. There was always something else that was damaged.

 

Technically you could always do the 7805 bypass right away at install time. I have honestly considered this.

[+-^CrossBow^-]

Well, I made sure mine weren't shorted out, but the fact that it does get so hot has made me consider putting a 7805 back into it and doing the bypass.