Duo-R RGB mod (UPDATE) complete / impressions and advice

[mackdanger]

Well, I finally got lucky and found a Duo-R for a price that was only moderately stabby, so it is time for some RGB action. Here's the deal. I am using the old school transistor based amp since I can easily get the parts, and the one I put in my Ten no Koe 2 gives a great picture. I also use C-Sync for all my mods in conjunction with my Framemeister. Since I use the same cable between multiple systems, I will be installing my own Din that is not connected to the mother board.

So here are the questions. For cleanliness and keeping wires routed nicely, can I pull +5, GND, and audio from the points where the old din used to be and run those to the inputs on my amp? If so, looking at the top of the PCB where the old din used to be,and comparing it to this diagram http://www.gamesx.com/avpinouts/duoav.htm it appears that the points look like this:

Is that right? I uploaded the picture to my Twitter account since I don't have Photobucket or anything like that. The numbers written around the box where the din used to be are confusing me. I already have the thing pulled apart or I would check the points myself.

Lastly, the pins on that C6260 chip are way smaller than I thought. What gauge wire do you recommend? Thanks for your help.

[SephirothTNH]

I can't answer you on the din points.  I see no reason why it wouldn't work but I've never personally done it. 

About the C6260 pins.  I've used 28 awg ide ribbon cable on it with success.  It really wasn't that difficult using the ribbon cable.  Perhaps a slightly smaller or single strand wire might make it easier though.

[mackdanger]

I can't answer you on the din points.  I see no reason why it wouldn't work but I've never personally done it. 

About the C6260 pins.  I've used 28 awg ide ribbon cable on it with success.  It really wasn't that difficult using the ribbon cable.  Perhaps a slightly smaller or single strand wire might make it easier though.

Thanks for that. The smallest I had laying around was 24 and I could tell that was way too big.

***Update***
I went ahead and broke out the multi-meter and checked the points and the one I have labeled +5V in the picture on my Twitter feed is corrects. So I am assuming all the other ones are as well. I will update once I am finished.

[mackdanger]

Okay, I completed the mod and everything is good to go. It wasn't all bubblegum and angel farts though, so let me tell you how it went down so you may learn from it.

First, the picture I linked in my Twitter feed in the first post, is correct. If you remove the din connector and want to tap from the holes in the board, those are the points. If you want to save that picture for future quick ref, go right ahead. Now, onto the actual mod.

I used the old school transistor based mod for the reasons I listed above. I got everything wired up, kicked on the power and......nothing except sound. No picture at all. I looked everything over and everything seemed to be connected. I then thought perhaps I might have a bad component in my sync amp. So I disconnected the c-sync and hooked up composite video from the din and still nothing. I then worried that I may have cooked something. I made damn sure +5V was going to the right place, but even still I worried that I may have damaged the chip. So I restored everything to factory, turned it on and it worked.

At this point I was thinking my sync amp, maybe the transistor, was bad. So I opened up my Ten No Koe 2  and yanked the amp out of that one since I knew it was working. I got it all installed and it worked. Just out of curiosity, I put the amp that I thought was broken in my TNK2 and it worked. So what happened?

After thinking it over, I realized the only possibility would be that my initial connections to the chip legs were bad. I think the first time I attached the wires, I forgot to add flux and tin them up. I thought I had, but I remember at one point I got distracted answering the phone and making coffee. Therefore, I am pretty sure my initial joints were colder than a penguin's ass. Second time was a charm, so I will tell you how I did it and maybe it will help you.

I didn't want to put too much heat on the chip legs, so this is the kind of tip I used:
http://www.amazon.co.jp/%E7%99%BD%E5%85%89-%E3%81%93%E3%81%A6%E5%85%88-2C%E5%9E%8B-T18C2/dp/B004OR7UBM/ref=pd_bxgy_diy_img_y

I don't remember if that is the exact one, but that is the shape. The size of the flat area on the tip I have is tiny, barely the width of the legs on the chip. I then put some flux on the legs, added a little solder to the tip and tinned the legs. I then added some more flux and put a tiny bead of solder on the tip. I then positioned the wire and very lightly slid the tip over the tinned wire. The solder on the tip, plus the solder on the wire and on the legs, combined with the flux made a nice solid connection and the dwell time was probably about one second. The entire time, even when tinning the legs of the chip, I never once applied any pressure at all. I just barely touched the tip to the surface and let it glide over the leg. I will admit, holding that tiny wire still can be a little tough. Just do few dry runs to make sure you can hold it in place and then go for it.

I hope this helps anyone thinking about trying this mod. If you have any questions, give me a yell.

[NightWolve]

I was meaning to pass along Steve's RGB amp circuit for you, but I'd bet you probably already did the same design. You need:

3 x S8050 transistors (or the RadioShack 2n3904)
3 x 75 Ohm resistors
3 x 470 uF caps

Assuming one knows some basics, the connection would be +5V line to the collector pins of the transistors, base pins to RGB input lines, output emitters to +leg of 470 uF caps AND 75 Ohm resistors to ground, while the -leg of caps goes off to the jacks/monitor for each, etc.

Basically, you do this 3 times for each R G B line:



Sync can be tapped from the Composite signal at the Multi-AV out of course, the way the SCART standard does it (uses a full regular Composite signal for Sync). If you wanna play around amp'ing a clean Sync from the encoder chip, you might run into some trouble, but yeah. You could also try the same basic amp for Luma/Y (pin 40) and use that as your Sync source, that's a little cleaner than Composite as there's no Chroma, just the properly mixed Sync + Luma/Y.



If all else fails, Sync from Composite fails, Sync from Luma fails, or your own direct amp on the pin itself will not work, there's Steve's somewhat universal Sync amp to try as a last resort:

[mackdanger]

Actually, I hadn't come across that one. The amp I built was the really old one that came out of that Japanese PC Engine book a long time ago. The one you linked above looks really simple. Is the picture improved? Since those are for the RGB lines, is there a similar schematic for Sync as well? The reason I am particular about using C-Sync is because with my Framemeister, C-Sync gives me a solid image that never drops, stutters, or jerks, no matter what the sync level is set at. My Megadrive currently uses composite video for sync, and while I can get a stable picture, it will sometimes hiccup. It doesn't make the game unplayable, but it pisses me off when I am trying to record.

###EDIT###
I just noticed the pic of the sync amp you posted. It failed to load the first time so I didn't see it.

[NightWolve]

As a matter of fact, I showed Steve that Japanese one during the conversation and asked him if going simple like this was better.  He said, "they should run close, but mine should be a hair more accurate." So, slightly better and simpler. However, he just chose to go with using the full Composite signal for H/V Sync, the SCART standard. Offered no simple Sync amp, other than the universal complex one that I just showed you.

[mackdanger]

Well thanks for the helpful info. I have filed those pics away for future reference. If I were to use those simple RGB circuits you posted, in conjunction with the Sync amp from the old schematic, would that work? I may throw some stuff together this weekend and mess around. Thanks again for the help.

[NightWolve]

Yeah, it would. If your H/V Sync amp is working, you can leave it alone and just improve the RGB lines.

[mackdanger]

Sweet man, thanks. I think I will mess around with it this weekend. I wanted to use the newer TI chip based amps, but they are only three channel so no C-Sync.

[NightWolve]

Some notes:

** Where to buy Le Steve-approved S8050 transistors:

http://www.ebay.com/itm/50pcs-Transistor-S8050-8050-D331-NPN-Transistors-Triode-TO-92-/181523381554?pt=LH_DefaultDomain_0&hash=item2a43a2fd32

$1.85 WITH shipping, and boom, have a 50 pack delivered to your door! I bought 100, so I have plenty to spare to mess around with. As mentioned, the RadioShack 2n3904 transistors also work the same and produce the same results. But if you want the best, that's where to go.


** The voltage rating on a capacitor is the maximum breakdown voltage. The higher the rating, the better, but the more expensive, and the bigger that the capacitor will be. Since most gaming electronics run on 5 Volts DC, even a cheap 6.3 Volt rated capacitor is technically permissible. However, that's too close to 5 Volts and if you got 10-16 Volt rated ones, use those instead!

Just recently I opened up my now defunct DSL modem and saw three 1000 uF caps rated at 6.3 V that were already bulging at the top, meaning, they were a poor, cheap choice that weren't handling the heat and wear over time. Also, I was given a broken 19" LCD TV set from my neighbor instead of it getting thrown out that used 16 Volt caps in the 12 VDC area of the power module which on paper is permissible, but these caps bulged real bad, are ready to explode, and that's why the failure occurred... They should've used 25 Volt rated caps, but they went cheap, and the TV only lasted for ~3 years... Hopefully when I recap it for a Youtube repair video I'll save it from the dumpster.

[thesteve]

the advantage of my sync amp is it takes a millivolt input and outputs 5V TTL
the 1 from the old book offers no voltage gain at all