[fixed] Issue with NEC XM29

[Arino]

Hey guys!
I'm having some weird problems with my XM29, perhaps you can help me.
Mainly I bought it to use it via VGA and that works fine but when I hook up my Scart to BNC converter cable with any console plugged in, the aspect ratio of the picture is wrong by default. It looks like 16:9 but should be 4:3 of course.
I've tried everything you can do with the remote and someone told me the dip switches can't be set incorrectly since the monitor does not even feature any kind of widescreen mode. I even found someone who uses the same monitor with the same adapter cable and he does not have that problem! I just don't get it.
Can someone help? Thank you!

[mickcris]

Hey guys!
I'm having some weird problems with my XM29, perhaps you can help me.
Mainly I bought it to use it via VGA and that works fine but when I hook up my Scart to BNC converter cable with any console plugged in, the aspect ratio of the picture is wrong by default. It looks like 16:9 but should be 4:3 of course.
I've tried everything you can do with the remote and someone told me the dip switches can't be set incorrectly since the monitor does not even feature any kind of widescreen mode. I even found someone who uses the same monitor with the same adapter cable and he does not have that problem! I just don't get it.
Can someone help? Thank you!

Here is a link to the xm29 plus manual:
https://isurplus.com.au/manuals/NEC%20X ... Manual.pdf

perhaps the dip switches for the sync control aren't set correctly (see page 14 of the pdf)

this thread may have some answers in it also:
http://shmups.system11.org/viewtopic.php?f=6&t=34345

[Arino]

Okay someone told me he uses the same monitor and the same adapter cable and he has the same "issue", but he says there is nothing wrong, that's just how the monitor's setting is by default for the BNCs. He said I just have to stretch the picture to the borders and then it will be 4:3 because the monitor is 4:3. It annoys, why can't it be 4:3 by default? Why is it proper 4:3 by default when using VGA?
Anyway thank you guys for caring and trying to help!

[Xan]

You were probably feeding it 640x480 over VGA, that's a proper 4:3 resolution designed to be displayed with square pixels (or 800x600, 1024x768). No adjustment needed. Console games often weren't rendered in 4:3 internally, but designed to be stretched by the TV and displayed with non-square "pixels" to achieve a 4:3ish AR basically (CRTs don't have discrete pixels). The NEC might just not account for this by default, maybe because it isn't designed to display consumer media. You could also try feeding it a 640x400 DOS game over VGA and see what you get, chances are you will again need to adjust it.

[Ed Oscuro]

Well, I'd say the reverse: Most any classic TV or monitor just assumes it's getting a signal in the 4:3 aspect ratio and fills the screen. It sounds like this is another case of the XM29 being too clever - in this case, trying to guess the source aspect isn't 4:3 (wrongly).

[Xan]

Guessing based on what though? A CRT can't detect the exact horizontal resolution from what I understand, its enumeration on VGA monitors is derived from the horizontal frequency or it's just counting the lines and assumes something from that. Assigning a 16:9 AR to any hypothetical 720x480 signal doesn't sound clever, but more like terrible design, as we know of much more robust 16:9 implementations like the dedicated switches on PVMs or even pin 8 on SCART (which can still be troublesome, but at least usually overridden on the remote).

[Arino]

All information I can give you is that I get the same AR from all "4:3 consoles" I plug into the Scart to BNC converter cable.
A friend uses such a converter cable on his Sony PVM 2950QM and he says everything was fine by default then, no need to change the AR and his picture was also screen filling already (besides having the wrong AR, the picture I get is also a bit small).

Another interesting thing is this: as I said everything is fine when I use VGA, so also my Dreamcast runs perfectly by default on that screen via VGA (and looks ace!), but when I play Sturmwind I can only do that in real 16:9 (because the game switches to 16:9 when a 16:9 screen is detected or so, but the XM29 is 4:3). I mean I would prefer playing it in 4:3 but at least this is some real 16:9 so nothing in the game looks squeezed.

[kamiboy]

I never had this problem with my XM29. Something is askew with your setup.

[Ed Oscuro]

Guessing based on what though? A CRT can't detect the exact horizontal resolution from what I understand, its enumeration on VGA monitors is derived from the horizontal frequency or it's just counting the lines and assumes something from that. Assigning a 16:9 AR to any hypothetical 720x480 signal doesn't sound clever, but more like terrible design, as we know of much more robust 16:9 implementations like the dedicated switches on PVMs or even pin 8 on SCART (which can still be troublesome, but at least usually overridden on the remote).

I agree with you - but that it has this behavior is fishy.

Reading Arino's latest comment, could it be there is a default aspect ratio select option hidden in a menu? I should have thought of that instead.

[Xan]

when a 16:9 screen is detected or so

A Dreamcast has no possibility of reading the monitor's EDID, so no, it detects nothing. Also Sturmwind doesn't have a real 16:9 mode, but reading about the game it seems it runs letterboxed (see: http://dreamcast-talk.com/forum/viewtop ... 940#p64940). So... maybe the monitor somehow detects this and interprets this as 16:9? If your 15 kHz sources turn out to be PAL consoles running with borders, we have the answer.

[Arino]

I never had this problem with my XM29. Something is askew with your setup.

Which converter cable do you use?

could it be there is a default aspect ratio select option hidden in a menu?

No I reset everything already you can reset.

when a 16:9 screen is detected or so

A Dreamcast has no possibility of reading the monitor's EDID, so no, it detects nothing.

Haha sorry about that, don't know much about these technical things so far

If your 15 kHz sources turn out to be PAL consoles running with borders, we have the answer.

Oh no they are all 60Hz!

[Xan]

I've no idea then, but does it at least save your adjustments for all 15 kHz consoles? The issue seems to be only on the BNC inputs, because on VGA everything seems to be displayed as intended if I understand you right. Maybe the previous owner manually adjusted the BNC input to display anamorphic 16:9 sources correctly.

[Ed Oscuro]

Looking at this manual, I see (on pg. 40) there is an option for VIDEO MODE selection: AUTO, NTSC, PAL, or SECAM. Did you try setting it to NTSC or AUTO?

There's also an overscan function described on p.34 (SCAN SELECT) but this should affect the whole screen, not just one dimension.

[Arino]

does it at least save your adjustments for all 15 kHz consoles? The issue seems to be only on the BNC inputs, because on VGA everything seems to be displayed as intended if I understand you right.

Yes, the issue is only on the BNC inputs. I could save the settings but I don't like adjusting the AR by myself because I think the AR can't be correct or "perfect" then. So I think I will go back to my regular CRT TV (which I also like) when using certain consoles.
I'm sorry, I know many people dislike that kind of puristic behaviour but I just can't take it easy when it comes to some technical sides of our hobby

Looking at this manual, I see (on pg. 40) there is an option for VIDEO MODE selection: AUTO, NTSC, PAL, or SECAM. Did you try setting it to NTSC or AUTO?

Yes I have tried the different options of that switch already, it changes absolutely nothing in that case.

There's also an overscan function described on p.34 (SCAN SELECT) but this should affect the whole screen, not just one dimension.

Right, it enlarges the whole picture but does not affect the AR.

[Ed Oscuro]

Really strange. Thanks for your notes on this subject!

[Xan]

We all eyeball certain settings when calibrating our displays, and in your case it's not that difficult because you have the edges of the tube as a reference point of how a 4:3 AR should look like. I'd suggest you look into the 240p suite (which is available as an ISO for the Dreamcast) and put up the grid pattern, that way you can also adjust overscan depending on which consoles you want to use.

[Unseen]

I could save the settings but I don't like adjusting the AR by myself because I think the AR can't be correct or "perfect" then.

Why do you believe that some random settings from the factory, made many years (and operating hours) ago would qualify as "perfect"?

[Arino]

Good question :X