YPbPr to VGA converter board

Hello, new project here.

I designed a small (4cm x 5cm) PCB that serves the only purpose of converting YPbPr (component) video output to RGBHV (VGA). You can view this as some sort of clone of a X2VGA.

It is based on the LMH1251 IC and can be integrated with pretty much any device that can output progressive component output : 480p, 720p and 1080p(but only 30fps for 1080p). The LMH1251 supports interlaced conversion but your VGA monitor will likely not. I did not integrate a sync doubler circuit to get an emergency mode for 480i like on the X2VGA because I wanted the board to be minimal and I don't plan on use this feature anyway. If you want to set your Xbox(or other console) to 480p/720p use another cable and get it done!

This project was originally done in order to integrated into v1.6 Xboxes as native VGA is impossible. With a 20cm^2 footprint and less than 1cm in height it will fit just nicely in there.

Here are the specs:
- Impedance matching on inputs and outputs so you could use it as a standalone box
- Onboard switching powersupply 7V to 12V input possible(using LM2674)
- +5Vdc to -5Vdc swing triple buffer amp on RGB lines for signal flexibility
- Sync polarity manual selection
- Uses modern ICs so you won't have trouble finding some!

The project is going well, schematics and PCB design are done. Gerbers files were sent to fab house but I won't receive them before some time.

Here's the entire schematic:




Maybe you'll find odd names on it it's just that when I design footprints, I tend to use the part number of the manufacturer as it's designation so it's easier set-up my bill of materials. However all the symbols are accurate.

The PCB representation in Eagle:


Not much to say here for now, looks messy because all the significant layers are ON.

Crude render of the topside of the PCB:


As you can see it's pretty dense but it's the price to pay to get a small sized board. Anyway people who can successfully solder those TSSOP chips will have no trouble soldering the other components. The board is mostly designed to be all SMD components except for power connections and YPbPr inputs.

Here's the bottom side of the PCB:


Again it's a crude rendering. I placed a few useful infos like the corresponding imprints for the VGA-out solder pads disposition(the actual solder pads are not on both sides, only top) along with the usage of the +5Vdc connector. By supplying your own +5Vdc you can avoid soldering the other LM2674 and it's supporting circuit.





Here's the general layout of the PCB:



For those of you who already know of the LMH1251 you'll notice that it pretty much follows the schematic of the Evaluation board sold by Texas Instruments. Yes it does! Why re-invent a working design? All I did was changing the +5Vdc supply design and make the whole thing alot smaller by removing lots of test points and the VGA-in circuitry (yes the LMH1251 can act as a VGA-YPbPr switch).

The final product is then a small as possible board that serves the only function of converting Component video into RGBHV without compromising compatibility and reliability.

For now I won't release any of the files as it is still a work-in-progress! I don't want potentially bad files to spread and so people will start building their own prototype based on a faulty design. I will receive the PCBs, build two prototypes (I have 2 1.6 Xboxes) and report on how everything is going.

No worry, I will publish all the files so anyone could build their own. My goal is not mainly to make money out of this but I like to finance my projects with earlier projects! So I will probably populate a few PCBs and sell them :sneakiness:

 

Ok, I received the PCBs last friday and so proceeded to start soldering components on the YPbPr to VGA board... only to find out I screwed up the wiring of the voltage regulators ICs...

I made a new design and submitted to the PCB fab house. I should get them in 2 weeks... I took the opportunity to update the GC TOSLINK board to make it smaller by removing the whole switching regulator. If you mount the board inside, you'll be able to find a +5V source. So no regulator is needed.

 

will this board impart additional latency?

 

Well yes of course, you add a device in the middle of the transmission, the propagation delay will be a result of the switching latency of every transistors as well as any delay introduced with signal processing of the LMH1251 (main converter IC).

However I wouldn't fear about latency, you won't notice anything while you play as the propagation delay will likely be in the nanoseconds order!

 

Hello,

Did you test the board in different definitions ? SD, HD ... The VGA output sync and colors are correct ?
When do you expect to publish the PCB files (Gerber or Eagle ?) I will be interested to build my own board.

 

Sorry, I've been really busy with the purchase of my first house. I did receive the last batch of PCB but never had the time to build a unit. I'll probably get on it this weekend. Don't worry I did not abandon this project.

I will publish the eagle files so anyone can modify the project to fit their own needs.

 

all looking forward to an update, no worries, and congrats on your new house!

 

game over :
thank you

 

circuit with corrections

 

Are you planning on selling these at any point? I need a device like this, and I was planning on getting a Mayflash VGA001, which does the same thing. But if your design is cheaper and/or higher quality, I might prefer that. I would want it as an external device, so I could use it with multiple different consoles. A case would be nice too, but not necessary.

 

You should sell these, I imagine there's a healthy market for this. A great piece of kit for people who want to hook up progressive component sources to computer monitors, or to bypass the noisy A/D conversion on the XRGB-3's component inputs.

 

I'll take one !

 

I'd buy one this instant.

 

I think this is what I need.

 

Hello,
Any news about this converter?
Thanks.