Steve's circuit design is now more universal; it's able to work for many other consoles. The thread will remain NEC specific with a completed mod on my Turbo Duo some day I hope.
* A Simple Jailbar Fix Guide has been included. Check end of this post.
* Current Revision (8/24/2014): The latest 2014 design (over the 2013) adds a 470 uF DC filter cap for Luma/Y to bring the video signal closer to video standards and help eliminate problems like screen flashes, sync dropout, etc. Many other tweaks to note also, so it's significantly different from previous designs.
RGB and H/V Sync taps from 6260 video encoder chip: | Yellow is for H/V Sync, RGB pins are color matched. Exact:
pin 51 - Blue
pin 49 - Red
pin 47 - Green
pin 44 - H/V Sync |
** Parts List Review (Updated: 8/24/2014) **[ul][li]Resistors (15): A $10 general 500 resistor pack should have all values needed, check eBay.[/li][li]Capacitors (5): 1 x 22 μF, 1 x 470 μF, and 3 x 100 μF (
circuit operates at 5 VDC, so a cap voltage rating of twice or more is safe: 10 V+). A $10 capacitor kit should also have all values needed, check eBay.[/li][li]Transistors (7): 7 x model "S8050" and that's IF you want the BEST according to steve, but you can use the RadioShack favorite/standard, the 2N3904. You can buy 50 pieces of the S8050 transistor for about $2 bucks on eBay from Chinese sellers.[/li][li]Potentiometers: (3) 2 x 10,000 Ohms, 1 x 100 Ohms.
a) The 10,000 Ohm pots should be centered to 5,000 Ohms on both terminals to start the circuit off. Alternatively, you can substitute these pots with four 5,000 Ohm resistors in series, 2 for each line, with the center point soldered to the transistor base.
b) As for the 100 Ohm pot, you can either get it or fiddle around with 10 to 90 Ohm resistors from your pack to find the best output value for the Luma/Y. I'll try to determine the best value for this when I get a chance.[/li][li]Diode (1): One, any cheap low-watt model will do.[/li][li]PCB: One 5cm x 7cm board is good enough to build this circuit on. Have fun![/li][/ul]
This image is a little outdated because of how much steve changed the design. I will update it eventually. Stuff like the S8050 transistors shown is still relevant. It's just the capacitor types that have changed.
Notes:
[ul][li]If you can get a ceramic version of the 22 μF capacitor, that would be better as ceramics are non-polarized! The ambiguity here of voltage direction doesn't best lend itself for polarized aluminum caps. Ceramics start getting expensive for bigger caps such as the 100 μF and so forth, so just pay attention to the schematic for polarity when it comes to the aluminum caps that you'll have to use, same for that last 470 μF cap (
negative end goes to jack/TV).[/li][li]S8050, NPN transistors can be bought cheap on eBay by this
seller, yankee_electronic. A pack of 50 for ~$2 bucks, etc. Search his eBay store if he has them up for sale, and after purchasing, ask for S8050 so you get regular, full sized transistors and not surface mount, small type ones, etc.[/li][li]Pretty sure everything can be purchased at your local RadioShack if you're impatient, prefer retail options and go with the 2n3904. For caps,
the 470μF are standard, but cost a $1.69+ each, so are the 220μF, and the 22μF ones might or might not be there though. They have a
500 piece $9.99 1/8 watt resistor kit or a $13 1/4 resistor kit (1/8w is fine!). PCB boards are $2.19 each, but for that much money, you can buy 10 pieces from a Chinese seller on eBay... There is a
15 pack of transistors, 5 of which are the 2n3904 needed for about $2.99+ or so... As for RCA jacks, they are a complete ripoff at RS... So, in the end, I recommend just getting used to learning how to shop on eBay for this stuff. You'll have to wait longer, but your money will go so much further. Example, for $4 bucks I bought 100 S8050 transistors, the good kind that are steve-approved... They came, I tested them on my SNES mod, they work fine! With the same amount of money at RadioShack, I get only 5 of the needed transistors and they're generic... Pathetic![/li][/ul]
Cheap hobbyist PCBs are plentiful on eBay (bought 10 pieces for $2 bucks) such as this 5cm x 7cm board which is perfect for this mod:
These wall plate gold-plated RCA jacks are also perfect if cheaper than buying 3 jacks individually, though they usually come in standard yellow (composite), white, red colors, but nothing a little good blue & green nail polish can't solve to give you the proper coloring for component jacks as I did here:
EBay Search for
"rca wall plate" with or without "component".This circuit is still a WIP and subject to revisions. I have yet to build mine, though I was responsible for pestering steve to help me when I tried to use the R-Y/B-Y outputs off the HuC6260 chip, but we eventually found that repairing these signals outputted by the chip was not worth the trouble and that led steve to later design the Red/Blue/Y mixer you see above! There are plans by BlueBMW and steve to manufacture professional printed circuit boards of this, so you may be able to buy one from them in the future instead of building it yourself. But I think this will be an enjoyable mod to perform yourself (building the circuit), so that's why I'm not gonna wait.
Screenshots of the first circuit built for one of steve's customer can be found here:
http://pcengine.freeforums.org/rgb-mods-t174-10.html
Jailbar Fix Guide - It is also recommended that you perform this simple mod to eliminate the "jailbar" problem that can occur in some cases.
https://www.pcenginefx.com/forums/index.php?topic=13231.msg287992#msg287992
A little History here with the old design of the circuit. Steve said the customer was getting "shadowing" effects with this circuit. It tried to use the existing Luma/Y that the chip produces and mix it with RGB Red and Blue, but steve concluded there was a syncing issue with doing that causing the "shadowing" and what not, so he decided he would have to tap RGB and Sync to fully produce his own matching Luma, making the new/current design far more complicated. Anyhow, I leave a link to the old design for reference and just in case for others to fiddle with.
http://i237.photobucket.com/albums/ff216/Sephiroth1975/General/NECHuC6260YPbPrMod.png
