SECAM intelli RGB

[YannAros]

HDMI capable is a tad bit more complex. Best solution is to squeeze in the console a rgb mod like mine and a rgb to hdmi converter from Chinese vendor. I haven’t one myself so I can not test and point you to one that would be working. What is almost certain is that all of this will fit inside the Intellivision.

[emmanuelf]

Hello,

How did you solved the funky non compliant sync signal problem?

Most modern tv/panels/converters do not tolerate the absence of hsync during/around vsync.

Glad to see that you use a proper output buffering chip. But keep in mind that all signals should be buffered, even csync is subject to 75ohm loading.

[YannAros]

The funky non-compliant sync signal problem isn't solved, but what I've found out is that if I use "V5" inverted as a sync signal I have a nice stable picture on my 2 monitors that didn't work cleanly with the standard sync signal.

I've put the possibility to switch between these 2 solutions on the PCB.

 

My investigations tend to tell me that the issue is not the missing HSYNC pulses during/around VSYNC but the length/position of the HSYNC pulses.

I do not have an OSSC, but 2 monitors that didn't sync correctly, for both of them, I was able to display an image by filtering CSYNC with a simple capacitor to GND or by using inverted "V5" as CSYNC.

 

The sync is buffered enough by the 74HCT00 that can provide up to 25mA.

Only 10mA is drawn from it's output (470 + 75 Ohms load).

 

 

[emmanuelf]

Ok good to know ?

[YannAros]

Did anyone investigate lmh1980 or lmh1981 IC to extract and reconstruct sync signals on an Intellivision?

[emmanuelf]

The current belief is that the problem is the missing hsync pulses. LMH1980/1981 will not solve it.

But you are by experiments thinking that it is more a timing problem on the hsync pulses than a problem around the vsync.

It should be confirmed by proper measurement on a scope. Perhaps timings IS the problem, perhaps trickling the vsync timing one way or another ( inverted v5 or csync slowing) minimize the missing pulse problem.

Investigating all this is on my todo list. My idea is using a little fpga to drive a standard video dac to act as "no longuer available/obsolete" ramdac and to what is need to proper reconstruct a compliant csync.

But I have no time now to put all this on the bench ....

 

[+DZ-Jay]

On 11/7/2020 at 11:54 AM, First Spear said:

I have one of these. I would love to pay someone to make it HDMI capable.

 

Me too, or at least composite.

[YannAros]

I’m not going all the way to hdmi but rgb to hdmi devices are available from many places and might do the trick