New 7800 S-Video Board available

[+JAC!]

On 8/2/2019 at 9:02 AM, JAC! said:

By trimming the potentionmeter I can make more shades show up about 3 or four. But the sequence is wrong, no matter which order I use. In fact it looks like one of the bits (B2 or B1) is inverted. On the other hand that is not possible, because black is displayed as black and white as white...

 

EDIT: I've traced the lines from the TIA and verfied these connections:

 

Wire / TIA / Board

WHI = LUM2 = TIA 6 = R1 = 470 Ohm
VIO = LUM1 = TIA 5 = R2 = 160 Ohm
ORG = LUM0 = TIA 7 = R3 = 912 Ohm

 

Here R2 looks totally wrong for me. It should be tween R1 and R3.

Finally with the help of a logic tester and oclilosope I was able to get it working. Here's what was wrong:

- the R1 and R2 that were pre-populated on the board were swapped.

- Rx for LUM2 must be 100 Ohm, not 160 Ohm get correct results for the brightnesses.

- One LUM output of the TIA was totally broken and one "only" half.

 

What a trip... but now it finally works. I description in the manual which resistor is is supposed to have which value/purpose would really have helped.

[haightc]

I have a 2.31 so what are the recommendations for resistor swaps

[shertz]

Brining this thread back to life.  Is this kit still being made.  I would like to buy one.  Thanks!!

[+DrVenkman]

8 hours ago, shertz said:

Brining this thread back to life.  Is this kit still being made.  I would like to buy one.  Thanks!!

On the off-chance it’s not, The Brewing Academy sells @Bryan’s UAV board under license here: 

https://thebrewingacademy.com/collections/ultimate-atari-video-uav

 

Currently closed for vacation but it will be back in a few weeks.

[+-^CrossBow^-]

10 hours ago, shertz said:

Brining this thread back to life.  Is this kit still being made.  I would like to buy one.  Thanks!!

I don't know if Magic Knight still visits this site and still offers these for sale, but having said that, I have a few of them on hand that I've already replaced the adjustment trimmer with a 5k to better dial in the settings vs the original 10k that was used along with empty PCBs that can be populated for use if you would rather assemble your own with components you have on hand or purchase.

 

 

[Albert]

8 minutes ago, -^CrossBow^- said:

I don't know if Magic Knight still visits this site and still offers these for sale,

He last visited on April 14, 2020.  Wouldn't hurt to send him a PM.

 

 ..Al

[+-^CrossBow^-]

4 minutes ago, Albert said:

He last visited on April 14, 2020.  Wouldn't hurt to send him a PM.

 

 ..Al

Good to know.

 

Having said that, he sent me like 20 unpopulated PCBs a few years back so I guess I would be a good source for them in the US if someone wanted one of these. The s-video from it is nearly on part with the UAV but as has been stated throughout this thread, it does require dialing in the settings. With the new 5k trimmer in place, it is easier to adjust it for working on multiple display types but there can still be differences. I should think about sending one of these off to @ChildOfCv for him to take a better gander at sometime now that I think about it.

 

I need to go back through my PMs with MK because in playing with resistor values, I actually stumbled on a setup where combining the chroma and luma together for a composite output instead, resulted in one of the best looking composite outputs I've ever seen from an Atari system! But that too could vary from console to console and display to display type being used.

 

 

[ChildOfCv]

8 hours ago, -^CrossBow^- said:

I should think about sending one of these off to @ChildOfCv for him to take a better gander at sometime now that I think about it.

To reverse-engineer it?  

Just reviewed the thread since my attention was brought here.  The jail bars are typically caused by the analog section being too close to digital radiation.  I haven't seen the bottom of the board, but it really should have a ground plane underneath if it doesn't.  Might also be good to re-design with surface mount components so that there are no "antennas" sticking through board.  That could also reduce its size so that it can be located further away from the other electronics.

 

One interesting idea would be to design a board the right shape to replace the RF board inside of its shielded box.  That has potential to remove unwanted interference (after all, that's the primary reason for shielding the RF board).

[+-^CrossBow^-]

Well, there are two styles of the PCB that MK used. There is the usual rectangular PCB that measures about 3x2inches in size I think? Pretty decent size even with all through hole components on it. I don't recall if there is a bottom ground plane on it or not. The other PCB design is actually shaped and silkscreened using his little Knight character logo on them. I've not populated any of those PCBs but it is the same scheme just in a different PCB form factor. I'm not even sure if he ever publicly has shown off the Knight PCB versions?

 

And not so much to reverse engineer it, just to see if you wanted to do anything with one of them I guess?