(Today is National Retro Day)
I'm adding HDMI output to my vintage Atari 800XL 8bit computer to project it on my large TV.
I'm a novice.
I've built a circuit for "High Speed Analog RGB to YPbPr Converter" using an LT6559 & LT1395 to "map RGB signals to YPbPr".
It doesn't seem to work and it could be because of something I don't know about or how to solve.
(Ugh. I've built & verified it 3 times now)
Could someone provide a suggestion on what to check?
Clarifications:
So far I wonder:
AN57 - Video Circuit Collection
https://www.analog.com/media/en/technical-documentation/application-notes/an57fa.pdf
See Figure 16.
Parts:
Looks simple enough. The surface mount chips were hard, but I got good at it.
I verified everything over-and-over, but the YPbPr Component out doesn't work or look right.
![1709015876757.png 1709015876757.png](https://forum.allaboutcircuits.com/data/attachments/303/303918-b4e78cb651938e2decc5cbc111326147.jpg)
Shows my prototype as bread board and in soldered form.
Neither build produces a recognizable signal on Y, Pb or Pr lines.
![1709015962720.png 1709015962720.png](https://forum.allaboutcircuits.com/data/attachments/303/303919-befe98535271b1dabd9ba71a643800d5.jpg)
This shows the reasonable red and green signals coming from Analog RGB.
(I don't have typical color bars on hand)
![1709016033562.png 1709016033562.png](https://forum.allaboutcircuits.com/data/attachments/303/303920-3ac9f965f60dda240bee709d4c1509ae.jpg)
(If you ask for details or suggest check this/that, I'll happily check and post results)
I'm adding HDMI output to my vintage Atari 800XL 8bit computer to project it on my large TV.
I'm a novice.
I've built a circuit for "High Speed Analog RGB to YPbPr Converter" using an LT6559 & LT1395 to "map RGB signals to YPbPr".
It doesn't seem to work and it could be because of something I don't know about or how to solve.
(Ugh. I've built & verified it 3 times now)
Could someone provide a suggestion on what to check?
Clarifications:
- I have added VGA, the source of my Analog RGB (but it does 15KHz, which isn't compatible with most monitors)
- I have a small RetroTink line doubler that can convert old Component YPbPr signals to HDMI (typical VGA to HDMI adaptors don't work due to 15KHz). RetroTink 2x Classic - https://junkerhq.net/xrgb/index.php?title=RetroTINK2X
- Together the RetroTink and this circuit are small enough to fit inside the Atari computer, and should have VERY low latency
So far I wonder:
- Am I powering the parts properly?
- LT1395 says usually wants +V and -V, but I gave it +5V and G
- LT6559 says +5V and G are fine
- Circuit description says I need sync signal embedded.
- I thought my RetroTink could use signal from Composite input with Component inputs, but that may not be happening.
- I might not have it, and don't know how to check or fix it.
- Quote: "As with the previous circuit, to develop a normal
sync on the Y signal, a normal sync must be inserted on
each of the R, G, and B inputs or injected directly at the Y
output with controlled current pulses"
AN57 - Video Circuit Collection
https://www.analog.com/media/en/technical-documentation/application-notes/an57fa.pdf
See Figure 16.
Parts:
- LT6559 - https://www.mouser.com/ProductDetail/584-LT6559CUD#PBF
- LT1395 - https://www.mouser.com/ProductDetail/584-LT1395CS5#TRMPBF
Looks simple enough. The surface mount chips were hard, but I got good at it.
I verified everything over-and-over, but the YPbPr Component out doesn't work or look right.
![1709015876757.png 1709015876757.png](https://forum.allaboutcircuits.com/data/attachments/303/303918-b4e78cb651938e2decc5cbc111326147.jpg)
Shows my prototype as bread board and in soldered form.
Neither build produces a recognizable signal on Y, Pb or Pr lines.
![1709015962720.png 1709015962720.png](https://forum.allaboutcircuits.com/data/attachments/303/303919-befe98535271b1dabd9ba71a643800d5.jpg)
This shows the reasonable red and green signals coming from Analog RGB.
(I don't have typical color bars on hand)
![1709016033562.png 1709016033562.png](https://forum.allaboutcircuits.com/data/attachments/303/303920-3ac9f965f60dda240bee709d4c1509ae.jpg)
(If you ask for details or suggest check this/that, I'll happily check and post results)