No video

[alex3331]

Turned on the first time; no RGB video on pins 22, 23, 24 of VDP With the scope:

Synchro (pins 5, 6) - normal CPU clock (pin 8 ) - normal CPU is listing addresses

V9958 - pins 22,23 and 24 - 2.2 volts, no pulses. Any way to diagnose? Thanks

[skiselev]

It might be not VDP related at all. The MSX BIOS will not produce any video if RAM or RTC are not working. I can recommend trying C-BIOS image first, which will produce video output even without working RAM and RTC

[alex3331]

Thanks, can you give me a reference for the image?

On Sat, Jan 29, 2022 at 2:27 PM Sergey Kiselev @.***> wrote:

It might be not VDP related at all. The MSX BIOS will not produce any video if RAM or RTC are not working. I can recommend trying C-BIOS image first, which will produce video output even without working RAM and RTC

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[alex3331]

I am using RGBS-VGA and RGBS-HDMI converters (negative CSYNC) with all my retros; Omega J5 RGB socket does not seem to have S pin. How is synchronization arranged on J5? Can I get synchro from VDP pin 6 (CSYNC) inverted by U43C (Q2 installed)? The scope shows correct timing and polarity. I looked at CXA1645 datasheet and it does not mix in SYNC with RGB outputs.

[skiselev]

I might be mistaken, since I haven't used my Omega with RGB, but I think RGB monitors, at least with SCART, use Composte signal for synchronization

[alex3331]

You mean Composite Video or Composite Synchro? Composite Synchro is working OK. Will start checking soldering; as well as checking signals with scope.

Sent from my iPad

On Jan 30, 2022, at 10:34 AM, Sergey Kiselev @.***> wrote:

I might be mistaken, since I haven't used my Omega with RGB, but I think RGB monitors, at least with SCART, use Composte signal for synchronization

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[alex3331]

Computer works OK (changed processor) with CBIOS and regular BIOS. Video is horrible. It does not want to talk to my adapters. I need to figure out how to connect it to LCD monitor. Both my adapters so far do not work with OMEGA RGB output. How do people connect it? Alex

On Sun, Jan 30, 2022 at 11:33 AM Vinci18 @.***> wrote:

You mean Composite Video or Composite Synchro? Composite Synchro is working OK. Will start checking soldering; as well as checking signals with scope.

Sent from my iPad

On Jan 30, 2022, at 10:34 AM, Sergey Kiselev @.***> wrote:

I might be mistaken, since I haven't used my Omega with RGB, but I think RGB monitors, at least with SCART, use Composte signal for synchronization

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[skiselev]

I personally use S-Video. Composite video also works for me, although with lower quality. Several people reported success with using RGB monitors or TVs with SCART connector (common in Europe). In the latter case, the connector provides RGB and composite video, and the TV/monitor extracts synchronization information from the composite video signal. There are a few, not particularly expensive S-Video to HDMI converters on Amazon, such as this one: https://www.amazon.com/Converter-S-Video-Composite-Support-Compatible/dp/B08NWYQHB4/ Maybe give it a try? (and return of it doesn't work)

[alex3331]

I sure will. Let me play with the scope a bit more. I have seen somebody taking RGB from 9929 and adding a 2N2907 transistor amplifier to each channel to bring it to TTL level. I have the PCB already so may try.

On Mon, Jan 31, 2022 at 12:50 PM Sergey Kiselev @.***> wrote:

I personally use S-Video. Composite video also works for me, although with lower quality. Several people reported success with using RGB monitors or TVs with SCART connector (common in Europe). In the latter case, the connector provides RGB and composite video, and the TV/monitor extracts synchronization information from the composite video signal. There are a few, not particularly expensive S-Video to HDMI converters on Amazon, such as this one: https://www.amazon.com/Converter-Composite-Adapter-Support-Blue-Ray/dp/B07GVDWGK8/ Maybe give it a try? (and return of it doesn't work)

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[skiselev]

Analog RGB voltage is normally much lower than 5V. For example, VGA ranges from 0V (black/no color component) to 0.7V (white/full intensity). CGA and EGA used 5V TTL digital signal, but I assume that's not what you want.

[cristianoag]

I'm using mine with RGB currently, but I noticed it is super sensible to the power source. I have multiple 5V power supplies, including my bench device and I only manage to make RGB work with one of the power supplies. I didn't check with scope yet, but that is strange. While it works ok in S-Video and Composite with any 5V power source, RGB only works within specific parameters.

[alex3331]

After I fixed my VDP issue RGB works fine for me. I use cheap RGBtoVGA adapter based on 8220 chip. The board is $25 on Amazon. Power supply is a cheap 5 v 2.5 a. If everything is OK, Omega does not pull a lot of current

On Mon, Feb 28, 2022 at 8:41 AM Cristiano Goncalves < @.***> wrote:

I'm using mine with RGB currently, but I noticed it is super sensible to the power source. I have multiple 5V power supplies, including my bench device and I only manage to make RGB work with one of the power supplies. I didn't check with scope yet, but that is strange. While it works ok in S-Video and Composite with any 5V power source, RGB only works within specific parameters.

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[cristianoag]

What was the issue with your VDP?

[alex3331]

As it turned out, VDP was fine ; two RAM pins were bent, so VDP did not initialize properly. Now I have an extra chip which is tested and working.

On Mon, Feb 28, 2022 at 10:44 AM Cristiano Goncalves < @.***> wrote:

What was the issue with your VDP?

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