Cheap RGB encoder for supergun

[SAM]

Reconnected the Red, Green, Blue pins back to the PCB. It turns out that the connection of the Blue pin is damaged, I end up connecting the Blue pin back to the PCB with a wire.

---------------------------------------

Start tracing the lines on the PCB:

Found the starting points of the Red, Green, Blue pins on the other side of the PCB. The lines is then connected to an Orange SMD tiny retangular object, then another of the other color, and then another bigger one.

The lines spilt after reaching the second SMD objects, does this means the Orange SMD objects are the capacitors?

I tends to believe the Orange SMD objects are the capacitors, but when I measure the resistance of the Orange SMD objects and got a reading. As oppose to no reading to the 0.1uf through-hole ceramic capacitors I used last night.

But then that might be the difference that make the chip work.

[SAM]

iatneH could you take one more photo, so that I could take a closer to the soldering points of the Red, Green & Blue wires? Thanks in advance.

BTW, the version of PlayStation you use for the mod should be able to play VCD.

P.S. - I would probably doing some try via error tonight.

[SAM]

Failed, again. Still got mono (Blue) color image.

After fooling around for hours, I think I accidently damage the oscillator on board. No matter what I do, I only got Black & White now.

Since the on board oscillator is damaged, it might be a good idea to get the chip off the PCB and built my own circult.

Or should I try this mod again on another PlayStation??

[iatneH]

iatneH could you take one more photo, so that I could take a closer to the soldering points of the Red, Green & Blue wires? Thanks in advance.

BTW, the version of PlayStation you use for the mod should be able to play VCD.

P.S. - I would probably doing some try via error tonight.

I'll see what I can do, my camera should be able to take larger photos but I don't know how detailed I can make them.

I don't know if the PS1 I used can play VCDs... I was told it was one of the very early models (US version though) and it has built-in RCA jacks. But I'll never know if it can play VCDs because it was broken when I received it, that's why it was free :]

Alrighty, here are the pictures. My new camera is better than I thought


Picture of the whole underside of the motherboard, so you know where the closeup is.


Closeup of the motherboard underside.


Same closeup as above, but labeled. You should be able to find where the RGB lines go to the underside by looking at the top side. Trace from the chip until you get to a hole. R, G, and B should have their holes neatly arranged on the top side, so look for a similar arrangement on the bottom side. I have also labeled the paths, so you can see the lines from bottom side entry point, on-board capacitor, soldered wire, and where I cut the original lines with a knife.

Note: click on the thumbnail to open a window, and click on the image again to show it at full size.

edit: This is funny because I posted this as a "cheap" solution for the do-it-yourself-er... but I broke 2 Genesis systems before I got the PS1 version working, and you broke a PS1... so we did not end up spending only a small amount of money in the end

[SAM]

SUCCESS!!! Thank you iatneH, Thank you.

Working on the potentiometers to control the brightness now.

edit: This is funny because I posted this as a "cheap" solution for the do-it-yourself-er... but I broke 2 Genesis systems before I got the PS1 version working, and you broke a PS1... so we did not end up spending only a small amount of money in the end

Since my friend and I each need to mod a PS1, so each of us have only broke 1/2 PS1. Besides, we got some savaragable parts for sale, namely: three PS1 lens & two mod chips.

Anyone want a PS1 mod chip?

[matt]

FYI, the Saturn works really well for this too. Better than the PSX, IMO.

What's nice about the Saturn is that the RGB encoder circuit is fairly discrete on the motherboard, so it's easy to cut it out and use it on its own without having to keep the entire mobo around.

[iatneH]

Thanks a lot for your help matt, I don't think I could have done this without your prior help, even though I know I probably caused you some small grief in the past

I would never hack up a Saturn though... somehow I see them as rare and valuable systems to be worshipped and loved Whereas Playstations are easily available and one can hack them to whatever evil ends without regret.

[SAM]

Added the potentiometers....
....
....
....
COMPLETE SUCCESS!!!

The potentiometers not only allow me to tone down the brightness, it also elimate the horizontal jumpness when connecting to CPS2!!!

I had tried to elimate the horizontal jumpness for some time, have even tried adding a 2.2k omn & 5P cap at the sync line as per Notes 5 on page 12 of the CXA1645 data sheet.

But after adding the potentiometers, the horizontal jumpness magically elimated. I guess the output of the Red, Blue & Green lines of CPS2 are very close to 1.3Vp-p, when outputing in full power, like during the "Created by Cave" screen, it goes over 1.3Vp-p and caused interruption at the chip clamp operation as mentioned in Notes 1 on page 12 of the CXA1645 data sheet.

Hurray!! Sony!! Hurray!!!
This is the first time in my life, that I really feel happy with a Sony product.

BTW, I got a JORK unit for sale, anyone interested?

[iatneH]

So.... you had a spare JROK, but you went and hacked up a Playstation anyway -________-;;;;

I just find it very weird that your Progear wasn't working with the JROK.

[SAM]

So.... you had a spare JROK, but you went and hacked up a Playstation anyway -________-;;;;

Since the PlayStation mod successful, I have no use for my JROK unit now.

I just find it very weird that your Progear wasn't working with the JROK.

The JROK unit of mine only work for MageDrive, Saturn & DC. But it doesn't work on all of my PCBs, SFC & PlayStation...

Since Saturn & DC could output S-Video, so the JORK unit only acts as an MageDrive S-Video adoptors for me.

********************

EDIT : DON"T USE THE METHOD LISTED HERE SEE NEXT POST.
Okay, here is some measurements of potentiometers when cailbrate to the correct value.

Caps: 10uF
(You are free to use different values of Caps, but the resistance needed for the potentiometers' resisters would be different.)

Variable Resisters value:

For Toaplan/Taito board, 630 ohm

For CPS2, 280 ohm

BTW, you should not connect the 2.2K ohm & 5P resister at the sync in line otherwise it would cause some very slight freshing when connecting to a CPS2.

****************

EDIT:
Just done some measurement with the JROK unit, it uses 0.1uF Caps & 0 to 200 ohm resisters at its RGB in lines. So I think we might just make use of the onboard 0.1uF caps to build the potentiometers by only adding three 0 to 200 ohm resisters.

The unmarked chip looks very close to a CXA1645/2045 but it still refuse to work for my CPS2 Progear.

[SAM]

Go back to measure the resisters on the PS1 Board just before the RGB in's Caps. It reads a little less than 200 Ohm. So I use 0 to 220 Ohm variable resisters in conjuction with the 0.1uF onboard caps to build the potentiometers.

It turns out that without the 10uF caps at the RGB in lines, the resulting image becomes much sharper. I think this also reduce the load of the game system video chips connection to the moded PS1.

When connecting to CPS2, the resistance has to be redused to 20 Ohm;
when connecting to consoles, the resistance has to be 180 to 200 Ohm.

******************

Further Testing Result:

CPS2 (Progear)
Look great.

Gunbird 2 (PCB)
Look great too.

MageDrive
Well it got mild colour bleeds, still better than connecting via it composite video, just wondering whether the MD S-Video mod would give a better picture. The best way to hook up a MD is still using a RGB monitor.

Since my MD is model 1, I could mod it to output S-Video. But if it give somthing simliar to what I got now, it might not worth the effort. Anyone could tell me.

Saturn
The color seems richer if the system is hook up this way. Overscan problem (in games like DDP, Batsugun) still presist. This only cured by connecting to a RGB monitor.

PlayStation
Look almost as great as its native S-Video out. In order to make this connection, you have to get the composite sync from the composit video line via LN1881 chip. I guess if I hack composite sync from the PlayStation board, the resulting image would look the same as native PlayStation S-Video out. (I would try this sometime next week. )

PlayStation 2
Same as above.

Super Famicom
Not working, no image.
It seems that nothing could convert the RGB singal of a SFC...
Well, you do able to connect it to a RGB monitor.

DreamCast
Not working, why is it not working ??

Game Cube
I haven't made the GC RGB cable yet, so I can't test this.

GameBoy Advance
It seems that it would be quite complicated to get RGB from a GBA, it seems that you need some chips to convert it's internal vedio singal to RGB.... Anyone know how to get RGB from a GBA?

**********************

There is also video ground, which I connected straight to ground on the PS1 mobo, and audio ground. Audio ground is a weird one. At first I also connected it to ground but it was causing interference with the video. I disconnected audio ground completely and now both audio and video work fine.

It got interference because, the "audio ground" of a PCB is actually the -ve line of the specker. The PCB did put power to drive the speaker in both the +ve & -ve audio lines, just like a Hi-Fi.

Just try connecting only the -ve audio line of a PCB to the speaker (the other line use a ground line) and you would actual hear the sound of the game. Connecting only one speaker line would reduce the sound qulity of the game. You have to connect both to the speaker.

[captain ahar]

i've been following this for a bit, and just want to say, 'seriously cool stuff guys.'

[D]

i've been following this for a bit, and just want to say, 'seriously cool stuff guys.'

AMEN, modding rules, you can't beat the satisfaction of fixing something or creating new uses, trying out your creativity, saving loadsa bucks by pure inginuity. Great stuff, congratulations to those who have succeeded.

[SAM]

A notes for those who would use the Composite Video Out. It is said on the CXA1645 data sheet that you could reduce the cross color caused by the singal at the Y out pin, by adding a capacitor or a capacitor and an insuctor in series at the YTRAP (Pin 17) pin.

For more details please refers to notes 8 on page 13 of the CXA1645 data sheet.

I would check and see if there are anything connecting to the YTRAP pin on the PS1 board. If none, I think I had find a mod to sharpen the Composit Video of a PS1.

[SAM]

Och?!?!

My friend and I have successfully moded a PS1, then I bought another to mod for myself but when I opened it...

There is no CXA1645 or CXA2045 within the console.

I checked the model of the PS1 it is a SCPH-9003.

So...
SCPH-1001 (the successfully moded one)
SCPH-5500 (the one I broke)
SCPH-5903 (Got CXA1645 chip)
SCPH-9003 (no CXA1645/CXA2045)

**************************

So now I got a useless NTSC Japanese PS1 110V to 240V, already moded. With box, manual, etc. and it costs me US$48. Anyone one interested?

I guess I better bring it back to the orginal seller and see if I could exchange for another one.

**************************

More testing results:
Previous tests shows that the CXA1645 chip could not accept the RGB singal from Super Famicom or DreamCast, I thought might be the sync singal from these consoles are too strong that the chip couldn't handle. So I added a potentiometer on the sync line to tune down it power, but got no result. Still don't know why it won't work for DreamCast and Super Famicom.

[it290]

MageDrive
Well it got mild colour bleeds, still better than connecting via it composite video, just wondering whether the MD S-Video mod would give a better picture. The best way to hook up a MD is still using a RGB monitor.

Since my MD is model 1, I could mod it to output S-Video. But if it give somthing simliar to what I got now, it might not worth the effort. Anyone could tell me.

I have a model 1 (original, no TMSS) modded for S-Video, and I'm not sure it's totally worth it. The picture is much sharper than composite, but the banding problems are fairly severe on bright colors. You can see this with composite too, but the added sharpness really makes it stand out. It looks great when the images is made up of mostly subdued colors, though.

From what I've heard, the best Genesis model for S-Video is the model 3... even though the compatibility sucks on that unit, it has the best quality encoder (Sony CX series).

[SAM]

There are many hardware revisions of PS1, so I can't guarantee the motherboards will look the same.

IIRC you need a 3001 or earlier.

It should be 5xxx or earlier.

SCPH-1001 (the successfully moded one)
SCPH-5500 (the one I broke)
SCPH-5903 (Got CXA1645 chip)
SCPH-9003 (no CXA1645/CXA2045)

For 9xxx or later inlude PSOnes (those slim console which has a seperate power transformer unit), uses another video encoder chip, the A2106R, which got no info avaliable on the net.

[matt]

From what I've heard, the best Genesis model for S-Video is the model 3... even though the compatibility sucks on that unit, it has the best quality encoder (Sony CX series).

The Gen3 is by far the easiest model to modify, but I don't think the S-Video you get is any better. The vertical banding is still there and quite evident.

Compatability on the Gen3 isn't all that bad - there are a few games that won't run on it, but we don't care about most of them. The biggest annoyance with it is that there's no stereo sound.

[SAM]

It's me again. Yes, I am not finished with this mod.

Okay, my friend and I did the mod for another PS1 (the successful modded belongs to my friend, so we need to mod one more for me), this time we used a 5xxx model.

Everything go fine, until the final testing. What happened is that the color of this modded PS1 look washed. Although it give a sharp image, the color looks washed and dim.

After some checking my friend noticed that on page 12 notes 2 of the CXA1645's data sheet it said:

"Be sure that analog RGB signals are input at 1.0Vp-p maximum and have low enough impedance. High impedance may affect color saturation, hue, etc. Inputting RGB signals in excess of 1.3Vp-p may disable the clamp operation."

It turns out that I am using a different kind of variable resisters this time and these resisters got a higher impedance than the ones I used on the previous mod (Their resistertance is the same). I swoop in resisters I was using in the last mod, the color becomes rich again.

So if you got a washed screen, try using a different kind of resisters with a lower impedance.

[SAM]

A notes for those who would use the Composite Video Out. It is said on the CXA1645 data sheet that you could reduce the cross color caused by the singal at the Y out pin, by adding a capacitor or a capacitor and an insuctor in series at the YTRAP (Pin 17) pin.

For more details please refers to notes 8 on page 13 of the CXA1645 data sheet.

I would check and see if there are anything connecting to the YTRAP pin on the PS1 board. If none, I think I had find a mod to sharpen the Composit Video of a PS1.

Sony had already added a cap at pin 17 in the PS1. My friend and I had tried to replace it with a cap with higher capacity to get a sharper screen.

The result is a burr screen with well definded color. The burrness is caused by lowing of the resolution. My conclution is one could use a variable cap here to adjust the sharpness of the Com Video out here. For better result you should use different cap values for different PCBs.

Well, the result couldn't match using S-Video nor SCART RGB.

[Soldato J]

You guys are like evil Shmup geniuses......

Bravo

[iatneH]

It's me again. Yes, I am not finished with this mod.

Me neither. Watch out SAM, this post might make you spend more money again.

In my first post I wrote that I fried 2 Genesis/MegaDrive systems. Well, I hacksawed the Samsung KA2195D chip out of one of the model 2 Genesis which I allegedly broke, and following the application circuit on the KA2195 datasheet, I was able to make a very clean and pocket-sized RGB->NTSC encoder.
All I had to buy were a box and some connectors, and a handful of capacitors and resistors and a crystal. And the Genesis, of course. THIS is the original mod which matt helped me get started

However, the KA2195 only supports composite video (blech), so I only recommend this to make a cheap encoder in a pinch, for the supergun newbie on a budget. I think SAM is still selling a much better JROK encoder for a very good price.

Also, I haven't added any potentiometers in my RGB input lines, so my colours are a bit on the bright side.


The wiring is very messy, but there are some funny things going on that I don't understand...I just followed the datasheet as closely as I could.


Everything is closed up. It's actually quite a tight fit inside, so I don't feel comfortable opening it up and adding potentiometers. I can probably make a separate DB-9 passthrough unit with pots on the RGB lines later.


The other side of the unit.

edit: SAM, did you put your potentiometers before or after the RGB caps?

[SAM]

Woo. This a very neat one. Congrt for your success.

Where is the power in? You draw power from the +5V DC of the RGB in?

Everything is closed up. It's actually quite a tight fit inside, so I don't feel comfortable opening it up and adding potentiometers. I can probably make a separate DB-9 passthrough unit with pots on the RGB lines later.

Tight fit?!?! It looks like there are still rooms in there.

edit: SAM, did you put your potentiometers before or after the RGB caps?

I add the potentiometers before the RGB caps.

[iatneH]

Woo. This a very neat one. Congrt for your success.

Where is the power in? You draw power from the +5V DC of the RGB in?

Yep, I have one pin of the DB-9 assigned to +5V, just plug and play (as long as my superguns/consoles use the same pinout)

Everything is closed up. It's actually quite a tight fit inside, so I don't feel comfortable opening it up and adding potentiometers. I can probably make a separate DB-9 passthrough unit with pots on the RGB lines later.

Tight fit?!?! It looks like there are still rooms in there.

The wires are a bit long, and the solder joints to the surface mount IC are quite delicate, so I don't want to squish things too much

I add the potentiometers before the RGB caps.

I also forgot to ask, what were the value of the pots you used?

[SAM]

I add the potentiometers before the RGB caps.

I also forgot to ask, what were the value of the pots you used?

I use a 0 to 200 Ohm pot on each of the RGB lines. You should look for some with as low impedance as possible, they would give richer color.

[iatneH]

Look out! It's the mod that never ends!

I finally got around to adding some potentiometers to the Genesis hack. Now the colours are down to a normal level.



I'll add the same potentiometers to the PS1 hack tomorrow (or soon)!

edit:
Done the potentiometers for the PS1 mod. I put them underneath the drive lid, so combined with the RGB input through the controller port, there are still no external signs of modification. Nice and clean.



I only tried it with Progear so far, but the colour balance is *perfect* now. However, there is still some horizontal jumpiness, although it's only noticeable during still screens.

So, I finally have proven (after SAM already did ages ago) that it's possible to make supergun RGB encoders with S-video for cheap! And with this, the project is concluded...for now...