Main > Monitor/Video Forum
2nd or 3rd attempt to a rgb tv mod. Any advice wellcome.
abispac:
--- Quote from: buttersoft on April 20, 2020, 08:33:09 pm ---VGA sync outputs at TTL levels = 5Vp-p. Try composite sync from VMM first. If that doesn't work, go back to separate H- and V-sync, then using a 480i mode that works on your arcade monitors, start with a 500R resistor and a 1k pot in each line, then merge and feed into the CRT where composite video would normally go in. Dial the pots around and see what happens.
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Thanks for the advice mr Buttersoft, im pretty sure with the correct pinout on my cable it will work rigth out of the box as the 8bit guy did too. Now i do have a question. Using vmm with Ntsc 60khz option, i almost had a stable image, using 15khz the image was a mess, do you think the 8bit guys was using ntsc60khz instead of 15khz? do you think 15khz should work? thanks for the help.
abispac:
just re-did my cable with correct pinouts, and colors are washed out, i get a semi stabilized image,using the composit option in vmm makes no diference, will keep tying.
abispac:
--- Quote from: buttersoft on April 20, 2020, 08:33:09 pm ---VGA sync outputs at TTL levels = 5Vp-p. Try composite sync from VMM first. If that doesn't work, go back to separate H- and V-sync, then using a 480i mode that works on your arcade monitors, start with a 500R resistor and a 1k pot in each line, then merge and feed into the CRT where composite video would normally go in. Dial the pots around and see what happens.
--- End quote ---
just finished buildind the cables,hope this is it
buttersoft:
NTSC would be 60Hz -NOT- 60kHz. Hz will be FPS. 15kHz is the scanrate. Section e) of the guide i wrote contains more info - https://www.aussiearcade.com/forum/arcade/m-a-m-e-emulation-projects-and-discussion/89704-a-guide-to-connecting-your-windows-pc-to-an-sd-crt-tv-pvm-or-arcade-monitor
NTSC60Hz would be a tautology, because NTSC is 60Hz. It may be referring to a preset in VMM like PAL, or Generic15? I'd start with NTSC at 480i and get that working first.
You do appear to have 3 wires coming from each 1k pot. But you only need 2, and one of them must go to the wiper in each case, otherwise dialing the knob will do nothing and you have a fixed 1k resistor. No harm having the third line, just don't connect it. Merge the right two output lines, and feed them into the composite video input. fire up your source, then dial the Horizontal sync line in, then the vertical.
EDIT Do not connect ground to anything here. Ground from the source can go straight to the set (i.e. the outer ring of the RCA jack, but not connected to anything in the sync circuit) And please keep all relevant info in one thread.
H-sync ---------500R-----------1k pot----------(nothing)
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----------------- (to composite video in)
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V-sync ---------500R-----------1k pot -----------(nothing)
abispac:
So the cable is a success with a regular arcade monitor and the weiya chassis, i know both 1k pots are working properly as they do scramble the picture if i play with them. However, nothing happens when i use them on the tv. Seem that im not getting sync from the yellow rca neither from the rf coaxial outlet. I need to figure out how to get sync from this. Heres a pic of my jungle chip
thanks for any advice