NISMOPC Posted December 27, 2021 Share Posted December 27, 2021 So, I actually have four, but one is CIB and practically new, so I did not test it. They are all NTSC. My main daily is a 7800 that I did an AV mod to (RF completely removed). The other two I received today as a lot from Ebay (stated not working and for parts). Not surprising, both of them have faulty tactile buttons (power button specifically) and they both actually work just fine. (Ordering replacement tactile switches today). Here is the issue. All three have color issues. They all show a solid bar on the 7800 Diagnostic Software, so they should all be correct colors. I've tried them all on 2 CRT TV's and 3 LCD's and same results. Using COMMANDO as my test game, the grass is blue, the water is extremely blue and colors are just off everywhere. The title screen of the soldier is all greenish blue. I've tested other 7800 games as well and they all have same issue. To get proper color, I had to adjust the 7800 color pot on the AV modded one to get as close to the proper color as I could, but now the diagnostic software shows 2 pink bars within the solid bar which means color is not correct. I did NOT touch the other two 7800 color pots. Thoughts? I read on one post that the 7800 colors get saturated over time and also depends on long unit's been on (warmer retains colors), but not sure I fully understood that as I have left them on for quite a while to see if any change in color. None. The 2600 colors are fine and I did not mess with that color pot. Quote Link to comment Share on other sites More sharing options...
NISMOPC Posted December 27, 2021 Author Share Posted December 27, 2021 (edited) Just to note: I am using the cheap and basic transistor/resistor AV mod on the modded one. Edited December 27, 2021 by NISMOPC Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted December 27, 2021 Share Posted December 27, 2021 You’re going to get different results between CRTs and modern flatscreens. Ideally, you’ll have one type of display you use the system with, and then go off the results there. Wait about 10 minutes for the system to warm up, then make any adjustments you need. If you’re saying that the 7800 color pot just doesn’t give you the right greens and reds/browns, then either the AV mod is faulty; the 7800 MARIA is putting out bad color; or something’s wrong in the NTSC colorburst signal. 1 Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted December 27, 2021 Share Posted December 27, 2021 Sounds like color artifacting, which one of my 7800s has pretty bad. I was advised that an S-Video mod may fix it because the chroma is split off the video. Quote Link to comment Share on other sites More sharing options...
Silver Back Posted December 27, 2021 Share Posted December 27, 2021 I’m not sure what the deal with 7800’s and color truly is. I have one that looks fine but once in a while the colors will start to go haywire (reds turn pink, colors get real bright or washed out, etc). Usually I’ll shut it off and then a few hours to a day later it’ll work fine. Then a month or so later it’ll do it all over again. I’ve never seen consoles quite like these. I have one back up (my childhood one) but I’m thinking of keeping a few extras because I really don’t trust them. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted December 27, 2021 Share Posted December 27, 2021 First you have to remember that there are only 2 color trimmers on the 7800. Bottom one is for the 2600 games and only adjust the color signal from the TIA side, The top one is for the 7800 games and as such will only effect 7800 colors. I actually use RevEng's utility cart and specifically the color chart there to adjust the 7800 colors when needed. But I only do so if they are grossly out of whack. Again, as the console warms up the colors will drift and change hues. Some of the hue changes aren't that drastic, while some like the title screen to choplifter can be quite a change with it being a teal or blue color sometimes on a cold start to being bright green after the console is warmed up. And as the good @DrVenkman stated, CRTs and LCDs produce the colors differently and I believe it has to do with the pixel counts being different between RGB pixels on LCDs vs CRTs. Color adjustments should be made on a CRT with the console warmed up using the RF output or composite. S-video can be used, but does not produce the artifacting color effect so again some colors will look different through s-video on both display types but CRTs are pretty consistent there. So that means that even if you adjust the color trimmer to a position you like on one LCD, it might not look the same on another as again it depends on how the LCD or any modern flat panel display has been color calibrated and adjusted. All the extra features like auto contrast and black level adjustments and such will mess with the colors also so it is best to turn off all of the extra stuff on modern displays for use with games to better dial in the colors. It is one of the reasons I've stuck with an older 1080P panel in my game room is that it isn't a smart TV and has few features to worry about mucking up the signal that I have to go through and adjust away. Quote Link to comment Share on other sites More sharing options...
Trebor Posted December 27, 2021 Share Posted December 27, 2021 4 hours ago, NISMOPC said: Using COMMANDO as my test game, the grass is blue, the water is extremely blue and colors are just off everywhere. The title screen of the soldier is all greenish blue. What was stated by @DrVenkmanis unfortunately the case, CRTs and LCDs can produced different colors for particular hue ranges. @-^CrossBow^-made excellent points too. The above quote from you though, tells me something else may be the issue. The 'green' looking like 'blue' under Commando will typically be experienced for just about any console when first turned on 'cold' (~24.7 degrees) despite display type. As a typical system warms up and transitions from 'cold' to a 'cool' state (~25.7 degrees), it will demonstrate the hue range transitioning. Even more so when reaching a 'warm' palette state (~26.7 degrees) and finally hot (~27.7 degrees), that blue will all appear green. It seems like the color pot may have been adjusted after the console already warmed up significantly, if not completely. This would result in having less degrees of separation between the console hues from the start when cold. Instead of 'ideally' the console being around ~24-25 degrees when cold-cool. The palette may be starting at ~22-23 degrees. That would be the outcome if a console's palette was calibrated to the factory setting ~25.7 degrees when at or closer to being "hot". The fix.. let the console completely cool down. Play it safe, give it an hour. Turn the console on and wait ~two minutes and then calibrate the colors. Do not wait an extensive amount of time. When the factory setting/color calibration is performed, it brings the console palette to ~25.7 degrees of separation among the hues. When this is performed to the console sooner, rather than later, after being powered on from a cold state, it allows room for the console palette to adjust matching the palette of many (most?) units out there with ~27.7 degrees of separation between the hues when 'hot'. Though, an argument can be made for possibly ~26.7 degrees of separation between hues when fully warmed-up, but certainly nothing less than that. For Commando, specifically respecting the greens, the developers selected the $Bx range. Hue range $Cx would have been a much better selection demonstrating a consistently green color; nonetheless, these are the specifics: Grass = $B1, $B3 Tree Tops = $B1, $B2, $B5 The $Bx range, as shown below, when there are less degrees of separation between hues, appears bluer. It becomes greener when the console warms up and the number of degrees between hues increases. However, if waiting too long to calibrate the console's palette, it will never reach that overall very green appearance, as it will demonstrate at most only ~25.7 degrees range of separation between hues, if the console was calibrated that way when the system was hot: Also please note, the color pot is extremely sensitive. The slightest movement can easily adjust a full degree. 1 Quote Link to comment Share on other sites More sharing options...
NISMOPC Posted December 27, 2021 Author Share Posted December 27, 2021 @Trebor @-^CrossBow^- @DrVenkman Thank you all for the details and suggestions. Makes sense. Only oddity with all the comments are my CRT's and LCD's all display the same colors. The RF 7800's and the AV modded one all show same colors. So at least I am getting consistency across all LCD/CRT TV's. All of my LCD's (and CRT's of course) are 4:3. Will try out RevEng's utility cart. I've got several utilities on my Concerto. Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted December 27, 2021 Share Posted December 27, 2021 29 minutes ago, NISMOPC said: @Trebor @-^CrossBow^- @DrVenkman Thank you all for the details and suggestions. Makes sense. Only oddity with all the comments are my CRT's and LCD's all display the same colors. The RF 7800's and the AV modded one all show same colors. So at least I am getting consistency across all LCD/CRT TV's. All of my LCD's (and CRT's of course) are 4:3. Will try out RevEng's utility cart. I've got several utilities on my Concerto. They are the experts! I would concur that the TV in my experience didn't make a big difference; however, I have the Longhorn/Electronics Sentimentalities AV mod, and that one made color artifacting worse. I have to get someone to do an S-video mod over it. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted December 27, 2021 Share Posted December 27, 2021 1 hour ago, Greg2600 said: They are the experts! I would concur that the TV in my experience didn't make a big difference; however, I have the Longhorn/Electronics Sentimentalities AV mod, and that one made color artifacting worse. I have to get someone to do an S-video mod over it. I'm no expert. I've just had a lot of 7800s cross my bench over the years is all. Quote Link to comment Share on other sites More sharing options...
Trebor Posted December 28, 2021 Share Posted December 28, 2021 On 12/27/2021 at 2:48 PM, -^CrossBow^- said: And as the good @DrVenkman stated, CRTs and LCDs produce the colors differently and I believe it has to do with the pixel counts being different between RGB pixels on LCDs vs CRTs. Some colors appearing differently is due to video standard differences. Such as Rec 601 for standard definition, and Rec 709 for high definition. Red carries more signal 'weight' under standard definition compared to high definition, while green carries more signal 'weight' in high definition compared to the 'weight' it carries in standard definition. Also, the strength of blue is stronger under standard definition compared to high definition. Note the RGB conversion formula differences: Rec 601: Y = 0.299R + 0.587G + 0.114B Cb = 0.564(B-Y) + 350mV Cr = 0.713(R-Y) + 350mV Rec 709: Y = 0.213R + 0.715G + 0.072B Cb = 0.539(B-Y) + 350mV Cr = 0.635(R-Y) + 350mV Consequently, certain hues will appear different when compared as they are being interpreted/decoded differently. 0.299R delta 0.213R = ~29% less red ratio strength under HD vs SD. 0.587G delta 0.715G = ~22% more green ratio strength under HD vs SD. 0.114B delta 0.072B = ~37% less blue ratio strength under HD vs SD. For any hue involving red and green, green has a net ratio gain of 51% under HD vs the same hue value under SD. For any hue involving red and blue, blue has a net ratio loss of 8% under HD vs the same hue value under SD. That is why a gold range under SD appears chanteuse or green under HD. The green ratio is greater. Some (blue-)purples may now lean more red purple instead, as the ratio of blue is less. This is true for the 7800 and other non-RGB palette systems (I.E. NES Super Mario Bros. sky.. red-purple under HD, blue-purple under SD). For convenience, from the aforementioned link, this sums it up nicely, [] mine: Quote When Rec. 709 [HD source] material is decoded with Rec. 601 [SD device display] numbers, the flesh tends tend towards magenta. In the reverse scenario [SD source material to HD device display], they tend towards green and appear more yellow...The Rec. 601 [SD] and Rec. 709 [HD] color spaces also differ in the transfer functions used, and the chromaticities of the primary colors (i.e. in a CRT, the color of the standard red, green, and blue phosphors are different). A solution is instead of letting the display device decode/interpret hues, utilizing hard coded RGB values will ensure more consistent colors across different display types. Hopefully, the 7800 console will have this as an available option sooner than later. Quote Link to comment Share on other sites More sharing options...
+DrVenkman Posted December 28, 2021 Share Posted December 28, 2021 8 minutes ago, Trebor said: Hopefully, the 7800 console will have this as an available option sooner than later. Gah, noooooooooo!!! RGB might as well be "HAHAHAHAAHHA NOT FOR YOOOOOOOUUUU!" in North America. There's NOTHING out here in consumer TV land (or even most computer monitors) that can work with RGB without a crap-ton effort, converter boxes, and/or lag. Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted December 28, 2021 Share Posted December 28, 2021 Mr. SainT is developing an RGB mod for the 7800 FWIW but that could be a ways off. He's likely to run into these color irregularities with the 7800 during his design stage. Quote Link to comment Share on other sites More sharing options...
Trebor Posted December 28, 2021 Share Posted December 28, 2021 On 12/27/2021 at 7:18 PM, DrVenkman said: Gah, noooooooooo!!! RGB might as well be "HAHAHAHAAHHA NOT FOR YOOOOOOOUUUU!" in North America. There's NOTHING out here in consumer TV land (or even most computer monitors) that can work with RGB without a crap-ton effort, converter boxes, and/or lag. The display device doesn't have to provide RGB input for the mod to work. The crucial 'RGB conversion' takes place internally on the mod board, intercepting the palette values and converts them, instead of allowing the display itself to interpret/decode the color output from the signal it receives. The same way Tim Worthington's RGB mods for the 2600 and NES work, which provides S-Video output and Composite output (along with RGB). The NESRGB mod allows three hard coded palettes to be leveraged. The 2600RGB mod allows three palettes for NTSC and three for PAL. From the aforementioned linked NESRGB site: Quote The NESRGB board effectively bypasses parts of the PPU - Palette RAM (Color Generator), Decoder, and DAC. These functions are duplicated in the NESRGB board with a focus on video quality. The timing of the video is unchanged so there is no lag (no framebuffer, no VGA, no HDMI, etc, etc), just non-interlaced 15kHz video output. From the 2600RGB site: Quote It works in a similar manner to my NESRGB board. That is, it sits between the CPU and TIA (the name of the Atari graphics chip) and stores the data which meant to be written to the TIA palette registers. The TIA is fed with dummy colours instead. The various luma outputs from the TIA, in addition to the colour data stored is then used to create a RGB version of the original video signal. Essentially, the board creates the RGB video signal by bypassing the colour generation logic in the TIA. The video timing is unchanged. A '7800RGB' mod would work in a similar manner just substitute "TIA" above with "MARIA". No more chartreuse-green for gold-brown, or too weak of a blue ratio for certain hues of blue-purple, making red too prominent. Hue palette values as they are intended to be seen, as demonstrated under a CRT, while also viewing the same hue interpretation/decoded colors under a modern display either via S-Video or Composite. Ideally, via HDMI optional output too. Quote Link to comment Share on other sites More sharing options...
electronicsibley Posted December 30, 2021 Share Posted December 30, 2021 On 12/27/2021 at 1:16 PM, NISMOPC said: So, I actually have four, but one is CIB and practically new, so I did not test it. They are all NTSC. Four 7800s? That’s paydirt! If you haven’t already, feel free to post a few pics, serial numbers and any interesting info in the thread linked below. I’ll be sure to add them into the list. Quote Link to comment Share on other sites More sharing options...
NISMOPC Posted December 30, 2021 Author Share Posted December 30, 2021 1 hour ago, electronicsibley said: Four 7800s? That’s paydirt! If you haven’t already, feel free to post a few pics, serial numbers and any interesting info in the thread linked below. I’ll be sure to add them into the list. Done! Quote Link to comment Share on other sites More sharing options...
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