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NEC TG-16/TE/TurboDuo => TG/PCE Repair/Mod Discussion => Topic started by: MNKyDeth on November 07, 2015, 12:03:50 AM
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Ok, so I ran into something I did not expect. This is a US Duo, forgot to specify.
The cap at C962 is in the path of the composite video. Removing this cap removes the composite video output. When doing an RGB mod I and I think others usually use the composite video for the sync.
Could you instead wire directly from pin 44 on the Hu6260 to pin 1 on the A/V output din socket?
Would this create a better picture than using composite sync?
I have not tested both ways but I am curious about this and I don't want to go through the hassle wiring it up if the knowledge is readily available.
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Using CSync should give you a cleaner picture.
But you may have problems if your viewing on a standard LCD/led TV as the sync is delayed.
So if your TV is a new type then stick with comp.
I have placed a switch to switch between the two.
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Yes, it creates a much better picture for RGB. Jail bars basically disappear altogether on certain games amd also helps with some TVs showing a checkerboard pattern. You can even just tap pin 44 and run it to the negative on the 470uf cap you mentioned because it is the same trace from the AV socket pin. You would however have to cut the trace for the regular composite video when doing this.
I was talking the idea over with thesteve today about splicing the two together without cutting and he told me that doing this can possibly over work/overheat the hu6260 chip overtime and kill it. Don't know for sure but why risk it.
So, the only way to do it is to install a switch to go between the two like Vimtoman mentioned. Otherwise damage could occur. Can't have both spliced together.
Here is a good tutorial minus the switch install. Shows where to cut to wire up c-sync instead of composite sync. http://www.otakus-store.net/en/content/6-guide-nec-rgb
I suppose another option would be to forgo the switch altogether and just mount RCA jacks to the rear of the DUO for future composite video use. Making the AV port for RGB only.
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I thought about this some. Why not just cut the pin on the A/V output that goes through the pcb? Then just run a wire directly to the metal in the back of the 8 pin din port.
This is of course if you want C-sync with no option for composite sync.
I guess this would depend on the situation for whatever someone was trying to achieve.
So a safe bet if reselling with RGB mod done to the system is using composite sync so people can use the composite A/V cable if desired. It just gives more options as an end result with the default layout of the system.
Honestly I have a Duo-R here with the RGB chip from turbokon. I did the standard swapping of ports to the 8din and in my framemeister I cannot see any jailbars at all. I don't even have the other pins grounded on the 6260 that is recommended to help with jailbars either.
I guess my next mod I will try with the RGB chip is to cut the leg for composite video and pull a wire from each to the metal in the back and use a switch to see if I can actually see a difference.
When this happens I will make sure to take some.screenshots so people can see side by side of the two sync outputs then.
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the picture is helped buy using pin 44 for sync instead of composite with some PC engine DUO and US Turbo DUO systems. Not so much with DUO-R or RX systems.
Then again, part of your lack in jail bars could be due to having a framemeister. Those things are awesome.
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I had a few minutes to play around tonight. So I decided to slap a switch in my machine SPDT on-on type switch.
I took the 8pin din header out and clipped the peg that goes through the motherboard. I then put a wire from Pin 1 to the center of the switch.
I wired CSync to one side from the Hu6260 chip and Composite sink from the hole under the motherboard where I snipped the pin to the other side.
It seems composite Sync works just fine, but when I turn off the machine and flip the switch. The CSync side has some heavy wavy lines. It's almost like interference.
The ground I am using is the one default one for the 8pin din, pin 3. Do I need to use a different ground?
This particular machine has ceramic caps for the jail bar fix on pins 41 and 43. The CSync wire was connected to the V2 Component mod. That mod worked fine so I assume the chip and wire are good. I put the RGB mod in and ran the CSync wire to the switch. Removing the component mod.
The interference I am not sure is from the ground or from the other Sync possibly? I am really at a loss for my my picture is like this. I linked some pics for compare.
Composite
(http://s5.postimg.org/5zgks3ew3/Composite_Sync.jpg) (http://postimg.org/image/5zgks3ew3/)
CSync
(http://s5.postimg.org/moi0o0bhf/CSync.jpg) (http://postimg.org/image/moi0o0bhf/)
For reference in case anyone wants to know what the original composite looks like compared to the above pics.
(http://s5.postimg.org/yf0jj4tnn/Composite.jpg) (http://postimg.org/image/yf0jj4tnn/)
I am mostly just trying to do this to see what if any real differences are.
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The Csync looks over saturated.
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Well, after a lot of experimenting I am wondering if I need a Sync Stripper in my scart cable.
I tried adjusting the various settings on the XRGB-mini but none seem to have any effect. It seems this is the signal I can getting from the console directly and not an issue with hardware in between.
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Ive just tried mine and the picture looks the same if either csync or comp.
No Framemiester to test with though.
I do have a 200uf cap in series with the csync to float it. Not sure if the Framemiester needs that.
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Well... I do have some extra caps, but no 200uF ones. I have a 330uF 16v and a 100uF 10v as extras at the moment. Well there is a 10uF but that is no where near the 200uF value. Would any of these caps be worth trying?
I do have the wire straight to the 8 pin din port from the hu6260. I will try it with one of these caps if they are deemed worthy. :)
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Try the 330uf.
What RGB circuit are you using?
I think that settings on the Framemeister is probably the answer.
Looking online they have Anmi,game etc that have predefined settings.
I think it does have a sat setting plus a A/D setting that may help
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I have adjusted every setting on the XRGB to make sure. I ended up putting every setting back to where I had it as that is where imo the best picture settings are.
I tested with the 330uF cap and still same issue for the CSync.
The composite sync is just fine so this Duo will be going that route for sure. I will test on another Duo here later in the week to see if it has the same issue or not.
That will tell me where I really need to look, either at the cable and get a sync stripper, or the console CSync is funky, or the XRGB-mini.
Thanks for the suggestions, it was worth a try. If I figure it out with the other system I'll still get some SS's up to show any differences between the sync's.
Edit:
I pretty much use Turbokons amps and region mods. So small and easy to use. Honestly I havn't tried anyone else's and I havn't made my own. The chips Turbokon sells have always worked for me. I have used the Component V2, several of the amps and a couple of the region mod chips already. Never had an issue after I got around my own learning curve. :)
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The Csync should not effect the picture.
There is a comment on the Framemeister firmware having saturation issues on 480i in component.
Maybe this is also effecting your setup.
It could be resolved in the next firmware update.
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Just FYI here are some pictures of how I had wired my switch.
There are several pads that go to the 5/8 pin Din that have dual pad arrangment with a small section of track joining them.
Cutting the track underneath allows you to disconnect the composite from the din so that you can use the pads to add wires.
Just scratch off the resist off the pads underneath to solder.
The pad connected to the din I had connected to the center connection of the toggle switch.
The other to the N/C pin of the switch.
The N/O pin of the switch has the CSync from HUC6260 via a Cap.
I used the other pole of the dual pole switch to hold the cap.
(http://i.imgur.com/OUAWtsn.jpg)
(http://i.imgur.com/Md2Mu13.jpg)
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Wow I was just about to start a thread asking why my composite does not work on my RGB modded PC engine duo. I have never seen any jail bars using the duo so the RGB must be using composite sync.
Would it be hard to restore this with a switch? I sometimes get the feeling to connect the Duo to a crt rather than my BenQ screen.
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It's up to you if you want to add a switch or not. In all honesty it may be easier to just add RCA jacks to the rear of the system for regular composite and the two audio channels.
You may have to look around the board to figure out where the composite was cut at. Some people do it right by the AV jack and others do it near the hu6260 chip.
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personally what i found using composite as sync in a SCART cable was i needed to add a 470uf cap across +5 and ground (at the scart plug) to eliminate the jailbars caused by the current through the cable ground caused by the sync separator
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Tried the cap and made no difference.
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I will be trying this again on my SuperGrafx, just waiting for caps and a couple other items before doing it. I will let you all know how it goes.
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Ok, so I was messing around again today with this.
I modded my Super CD-Rom 2 system for RGB output. Instead of pulling Composite Sync from pin one on the Din socket I cut off the leg so it wouldn't go through the PCB mounting hole.
I then ran a wire from the remaining Din socket leg to pin 22 on the expansion bus.
Now, in hindsight, I have no idea if pin 22 is Composite Sync or C-Sync. If pin 22 on the expansion bus is composite sync is it possible to get pure sync from someplace on the expansion bus port?
I was using this diagram of the expansion bus.
http://www.gamesx.com/misctec/pcebp.php (http://www.gamesx.com/misctech/pcebp.php)
Edit:
After some more poking around I decided to continuity test from pin 44 on the 6280A on my SuperGrafx to the same pin on the expansion port and I had sound. So it is CSync (pure sync) on pin 22-C and not composite sync. It seems to work just fine where it wouldn't on my TurboDuo.
I plan on getting some SS's of this system with CSync to compare it to one with composite sync. I also have a Component mod chip here from Turbokon and if I get some free time I will slap that into a system so I can get a 3way compare on my framemeister.
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Csync and composite sync are the same. Think you might be referring to composite video where you are saying composite sync above? The naming can be confusing.
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Diagram pin
Csync "Pure sync" is what you want .
Vid "Comp video" is what you cut off the din.