Omega MSX First Boot - Video Issue

Supporter (12)

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.

By sdsnatcher73

Enlighted (4298)

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.

By nullvalue

Supporter (12)

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.

By nullvalue

Supporter (12)

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.

By msxmakers

Hero (551)

13-02-2023, 17:23

nullvalue wrote:

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.

By nullvalue

Supporter (12)

13-02-2023, 17:38

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

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.

By serge_ua

Supporter (16)

26-06-2023, 19:45

Hi!

What about border color? Got the same issue, I bet first several boots were color 15,4,4 but now I have border with light blue..
Any ideas?

Many thanks,
Serge

By Grauw

Ascended (10821)

26-06-2023, 20:35

That doesn’t seem like a hardware problem. European BIOS ROMs use 15,4,4 by default but the Japanese BIOSes use 15,4,7. So one possibility is that you changed the BIOS ROM to a Japanese one. Alternatively, since the default colours are stored in the clock chip, if you or some software has changed the default colours and then written them to the clock chip, it would result in the default changing.

Try in BASIC:

COLOR 15,4,4
SET SCREEN

By serge_ua

Supporter (16)

26-06-2023, 20:51

Thanks!
You were right, software issue) setting the screen resolved the issue.
Just didn’t find msx2+ european pal rom and catch
something from msxmakers(msx2+ one from google drive archive)

Thank you again

By Pencioner

Scribe (1610)

26-06-2023, 21:28

afaik msx2+ were only Japanese so it is no surprise you can't find the rom

By serge_ua

Supporter (16)

27-06-2023, 10:08

Pencioner wrote:

afaik msx2+ were only Japanese so it is no surprise you can't find the rom

Hello Didus,
Glad to see you here.
Thanks for your answer, will try to find msx2-eu one.