Problems with the colors (especially blue) on the NES
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Problems with the colors (especially blue) on the NES
A while back I've got myself another NES for only 3.99€ in a yard sale. At first glance it looks alright and appears to be perfectly fine. Then I've noticed that the colors especially the color blue and everything containing it looks absolutely terrible.
I've looked at the output directly after the PPU which is weak (as expected) but otherwise completely fine. Even the colors are good.
Unfortunately I cant really fine any Information about the many trimmers on the PCB and in the RF-Modulator which might have to do something with it.
I've looked up the schematics and the only real problem could be the 2SA937 or anything in the RF-Modulator in my opinion. Would it make sense to swap out the transistor (since I've already got one of them)?
I've looked at the output directly after the PPU which is weak (as expected) but otherwise completely fine. Even the colors are good.
Unfortunately I cant really fine any Information about the many trimmers on the PCB and in the RF-Modulator which might have to do something with it.
I've looked up the schematics and the only real problem could be the 2SA937 or anything in the RF-Modulator in my opinion. Would it make sense to swap out the transistor (since I've already got one of them)?
Re: Problems with the colors (especially blue) on the NES
Just making sure, since it wasn't explicitly stated - this NES appears to be outwardly identical to another one you have, but blues don't work well on this one?
If so, go ahead and swap out the transistor - it's certainly easy and cheap enough to be worth trying.
If so, go ahead and swap out the transistor - it's certainly easy and cheap enough to be worth trying.
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Re: Problems with the colors (especially blue) on the NES
All I see is that the video levels are wrong, causing all $3x colors to clip to white. It's not specific to blues, as the $1x and $2x blue is still blue.
Re: Problems with the colors (especially blue) on the NES
Yeah that's exactly the case. The other one is the one which had the broken RF-Box. For now I'm going to swap out the transistor and recap the RF-Box and PCB.lidnariq wrote: ↑Sun Dec 12, 2021 10:30 am Just making sure, since it wasn't explicitly stated - this NES appears to be outwardly identical to another one you have, but blues don't work well on this one?
If so, go ahead and swap out the transistor - it's certainly easy and cheap enough to be worth trying.
Re: Problems with the colors (especially blue) on the NES
Well does this mean that the PPU is probably bad?NewRisingSun wrote: ↑Sun Dec 12, 2021 10:40 am All I see is that the video levels are wrong, causing all $3x colors to clip to white. It's not specific to blues, as the $1x and $2x blue is still blue.
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Re: Problems with the colors (especially blue) on the NES
No, I think that at some point in the video path from the PPU, the amplification of the video signal is incorrect. You mentioned the RF modulator -- does that mean that the signal is good when coming from the baseband composite AV socket?
Re: Problems with the colors (especially blue) on the NES
Unfortunately replacing the transistor and recapping the Board didn't fix the problem...
Re: Problems with the colors (especially blue) on the NES
I've tapped into the signals directly at pin 21 on the PPU and right before it goes into the RF Modulator at the output side of FC2... Really looks like its something inside the RF-Modulator
The first picture is at the output of FC2 and the second directly at pin 21 on the PPU
The first picture is at the output of FC2 and the second directly at pin 21 on the PPU
Re: Problems with the colors (especially blue) on the NES
The baseband portion of the RF modulator is pretty simple - it's something like a PNP-based emitter follower.
For example, look at my trace of an NTSC modulator:
viewtopic.php?p=131845#p131845
Or Electronix Corp's reverse-engineered one:
https://console5.com/wiki/File:NES-001- ... Switch.png
So you should be able to make similar guesses about rebuilding the baseband video path in yours
For example, look at my trace of an NTSC modulator:
viewtopic.php?p=131845#p131845
Or Electronix Corp's reverse-engineered one:
https://console5.com/wiki/File:NES-001- ... Switch.png
So you should be able to make similar guesses about rebuilding the baseband video path in yours
Re: Problems with the colors (especially blue) on the NES
It's a NES right? It should have composite output as well.
Re: Problems with the colors (especially blue) on the NES
Are the values the same on a PAL-system?lidnariq wrote: ↑Sun Dec 12, 2021 3:05 pm The baseband portion of the RF modulator is pretty simple - it's something like a PNP-based emitter follower.
For example, look at my trace of an NTSC modulator:
viewtopic.php?p=131845#p131845
Or Electronix Corp's reverse-engineered one:
https://console5.com/wiki/File:NES-001- ... Switch.png
So you should be able to make similar guesses about rebuilding the baseband video path in yours
Re: Problems with the colors (especially blue) on the NES
Uh ... maybe? Possible.
Re: Problems with the colors (especially blue) on the NES
Unfortunately not... the PCB looks completely different. I'll probably end up having to re-engineer the PAL-PCB because I cant seem to find a schematic for the PAL ones at all.
Re: Problems with the colors (especially blue) on the NES
Just take a look at how complicated/different the PAL version is in comparison to the NTSC version...
Re: Problems with the colors (especially blue) on the NES
The RF portion is much more of a mess than the baseband is.
I have no idea what the 6-pin SOT23 is, however, and no obvious guess.
I have no idea what the 6-pin SOT23 is, however, and no obvious guess.