YPbPr for CV - was Mystery Project

[+5-11under]

Alright, there's been enough answers right on the doorstop, mentioning ColecoVision and/or component video modifications. That's what it is. The last picture shows the power switch of the ColecoVision, as well as a green RCA connector, part of the YPbPr output.

 

Thanks for playing,

5-11under

[doubledown]

Alright, there's been enough answers right on the doorstop, mentioning ColecoVision and/or component video modifications. That's what it is. The last picture shows the power switch of the ColecoVision, as well as a green RCA connector, part of the YPbPr output.

 

Thanks for playing,

5-11under

 

I thought the component video challenge was already mastered! Don't forget to make accomodations for the digital audio outputs too.

 

[+5-11under]

Hi doubledown,

 

It has YPbPr output, plus red/white RCA connectors for analog audio output. It also has composite output (Ben Heckendorn style) for Atari compatibility. It does not have digital audio output.

 

This modification is for people (like me ) who don't have megabucks. This would retail in the range of $50 to $55 as a kit, including shipping, and is designed to be a good bang-for-the-buck A/V solution for the ColecoVision, and a natural progression from the ColecoVision's internal capabilities.

 

The "kit" mentioned above would be fully assembled, but would of course require installation to solder connecting wires onto the CV's PCB, drill holes in the outer case, and do some cutting to the shielding to make some space for the modification.

 

By "natural progression from the ColecoVision's internal capabilities", I mean this: The video chip in the CV naturally outputs the required colour difference signals (essentially YPbPr), just at a higher voltage level than normal, and without enough power to drive a TV. Therefore it's a relatively small step of attenuating and buffering to output YPbPr from a CV. Same goes for the analog audio output. The sound chip in the CV has an analog output, which is easy to tap into. Providing digital audio output, or VGA/HDMI video output may be beneficial, but the costs would increase out of the range of some consumers, and would require a greater transformation of the signals well beyond the CV's internal capabilities.

 

Feel free to discuss!

 

Thanks,

5-11under

[Artlover]

Will schematics be avaialble for people who want to make it themselves?

[+5-11under]

I don't have a schematic...

 

Take the outputs from the CV video chip (pins 35, 36, 38?). Each of those will go through the same type of circuit: put a ~3.3K resistor to ground at that point. At the same point, connect one end of a ~500 ohm potentiometer. On the other end of the potentiometer, put a ~100 ohm resistor to ground. I'm using the "~" symbol because I should probably review these values, although the listed ones work fine. At the same point (other end of the potentiometer), connect to one end of a ~22 uF capacitor. The other end of the capacitor connects to three items: a ~4.7K resistor to ground, a ~4.7K resistor to +5V, and to the input of an LMH6734 IC (pins 2, 5, 8?). Leave the other input pins open. You'll need +5V and ground on the appropriate pins of the chip, of course. Send the output pins of the IC to R, G, and B RCA jacks. I think that's it.

 

The most difficult part is probably dealing with the pitch of the IC leads. Options include using an adapter board to convert to a DIP package, which could then easily be hardwired in a variety of fashions, or sourcing another amplifier. Perhaps three of part number LM318 would work, although the surrounding circuit would have to change a bit.

 

Your costs will vary, of course, depending on how you build it. The way I'm planning, the costs for one unit is about $28 for parts, not including PCB, shipping parts, tax. Here's a list of what my costs would be for one unit, to see where you could save money if sourcing other components or using items you already have. I'll be building at least 10 for my own consoles, which will save me money by economics of scale.

 

$7.07 Buffer amplifier

$8.46 RCA connectors (6 various) (I already have some of these)

$0.43 SMT Transistor (for composite)

$1.17 SMT Resistors (13 various)

$4.00 Potentiometer (3)

$2.21 Wires

$2.25 Mounting brackets (3)

$1.32 SMT Capacitors (4)

$0.03 SMT Capacitor

$1.00 Header

$0.46 Connector

$0.30 Bolts (3)

 

Will schematics be avaialble for people who want to make it themselves?

Edited October 6, 2008 by 5-11under

[+5-11under]

Schematic created!:

 

 

Thanks,

5-11under

[doubledown]

Out of curosity, what type(s) of display(s) did you test this circuit with (ie, CRT, LCD, Plasma)?

[+5-11under]

Hi doubledown,

 

Two so far: A Westinghouse 42" LCD and a Panasonic 7" LCD. I've also got access to a 42" Samsung LCD and a couple of different 12-20" Sony CRT studio monitors, which I'll be testing soon.

 

Thanks,

5-11under

 

Out of curosity, what type(s) of display(s) did you test this circuit with (ie, CRT, LCD, Plasma)?

[Ikrananka]

Hi 5-11under,

 

Any update on progress with this component video mod?

[+5-11under]

Hi Ikanankra,

 

So far, I'm getting variable results on a couple of TVs/monitors. For instance, my Westinghouse looks great, although in the upper part of the screen there are some flickering (Colecovision sized) pixels (for example, in the game Squares!, the squares' corners rotate between rounded and sharp. Large blocks of colour, like in the Smurf's game also have some minor banding issues. It's fine for me, but I need to do more work on it to make this a wider-reaching solution.

 

Unfortunately, I haven't had too much time to spend on this lately. I still think about it, so I'll get back to it sometime.

 

Thanks,

5-11under

[Ikrananka]

Hi Ikanankra,

 

So far, I'm getting variable results on a couple of TVs/monitors. For instance, my Westinghouse looks great, although in the upper part of the screen there are some flickering (Colecovision sized) pixels (for example, in the game Squares!, the squares' corners rotate between rounded and sharp. Large blocks of colour, like in the Smurf's game also have some minor banding issues. It's fine for me, but I need to do more work on it to make this a wider-reaching solution.

 

Unfortunately, I haven't had too much time to spend on this lately. I still think about it, so I'll get back to it sometime.

 

Thanks,

5-11under

Hey , thanks for the update. Hope you manage to get back to it sometime soon