Omega MSX First Boot - Video Issue

بواسطة nullvalue

Supporter (12)

صورة nullvalue

13-02-2023, 06:17

Well, it could be worse! So I have this configured for NTSC, hooked up to via composite to a known working monitor but this is the output I get. I can barely make out the MSX logo during boot, then get snow on the screen which I assume is text but something's wrong. Can anyone tell from the picture what might be the cause? I've triple checked my jumpers and I burned an NTSC ROM image.

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بواسطة sdsnatcher73

Prophet (3967)

صورة sdsnatcher73

13-02-2023, 09:20

Do you have an RGB cable as well? I am not particularly familiar with the Omega but the composite signal is encoded by a chip from the outputs of the V9938/V9958. The chip responsible may be malfunctioning. Testing if the RGB output is working well would be a good indication.

Best to ask your question in this Official support thread as well.

بواسطة nullvalue

Supporter (12)

صورة nullvalue

13-02-2023, 16:35

You're right I think there is something up with that Sony encoder chip, but it could be that a signal is not getting to it. I'm going to take a look at the schematic and perform a few more tests.

بواسطة nullvalue

Supporter (12)

صورة nullvalue

13-02-2023, 16:59

Ahh much better - after checking the schematic, I found that I had installed a component (Q2) that was intended for PAL only and was not supposed to be installed for NTSC. After removing it boots perfectly.

بواسطة msxmakers

Hero (516)

صورة msxmakers

13-02-2023, 17:23

nullvalue wrote:

Ahh much better - after checking the schematic, I found that I had installed a component (Q2) that was intended for PAL only and was not supposed to be installed for NTSC. After removing it boots perfectly.

Hi,
To clarify this issue, Q2 is not for PAL support, Q2 is to work with V9938, be careful.
V9938 is the VDP for MSX2 generation, not too bad but installing Q2 with a V9958 may cause this chip be broken.
If you don't have a V9938, please, detach that transistor, you can choose PAL or NTSC changing its firmware and some jumper but nothing will be damanged.
So, How good your V9958 is working. Hannibal

بواسطة nullvalue

Supporter (12)

صورة nullvalue

13-02-2023, 17:38

You're right, I was just coming back here to clarify that but you beat me to it. Smile2

Well it displays the MSX logo properly at boot and is able to display the BASIC screen, so that's something. Hopefully not damaged? Gotta get my edge connector installed so I can try my Mapper Megaram cart. Also waiting on a couple IC's for my keyboard that weren't included in the eBay IC kit I purchased.