OSSC Pro – Advice on outputting 800×600 to a CRT tv

[rpgwaiter]

Just got the OSSC Pro, and I have a CRT monitor that takes VGA input. The monitor only works with 800×600@60 signals, and will display an error screen with any other.

I’m getting a feel for the OSSC Pro UX, but I don’t really understand how to force this resolution out of HDMI. My goal is to use an HDMI->VGA converter that should support this resolution, at least until the extra AV out boards are back in stock.

Anyways, how exactly do I set the OSSC Pro to output at this resolution? I’m testing with a PS2 over component cables but I’d eventually like to try a variety of consoles on this CRT.

• This topic was modified 2 months, 3 weeks ago by rpgwaiter.

[BuckoA51]

That would be very unusual to have a CRT monitor that could only do 800×600, most computer BIOS etc screens were not in that resolution. Anyway, you can use scaler mode to fix the output resolution to whatever you want.

[rpgwaiter]

I figured that much. I can see a “PC 800x600_60” option under scaler opt -> adv. timing but I don’t see a way to actually enable that output

[BuckoA51]

Thats input timings. Scaler Opt->Scaler opt->DFP/CRT output mode lists available modes.

Really none of the available output modes work?

[rpgwaiter]

No, the CRT really does only accept 800×600@60 for some reason. It’s a gateway monitor for some special PC (that I don’t own). Not sure why it has this restriction.

 

Edit: I’m not opposed to adding the new resolution myself and compiling my own firmware but I wanna make sure there isn’t another option first. If I do end up going that route I’ll submit a PR on GitHub.

 

• This reply was modified 2 months, 3 weeks ago by rpgwaiter.

[marqs]

Is that truly a 38kHz capable tube? It looks like a standard 15kHz consumer CRT TV with maybe just a VGA card containing a TV encoder chip that downconverts 800×600 to SDTV. Anyway, you can repurpose any of the output presets (e.g. 1024x768_60) into 800x600_60 by just adjusting its timings (via Output opt -> Adv. disp timing) and then selecting it when using scaler mode.

[Zacabeb]

Those giant Gateway Destination monitors were sold as part of their short-lived attempt at making a PC the center of the living room. They reportedly have CRTs with coils for the 30-40 kHz range, so from what I understand they display 800×600@60 natively.

The little information available on them however suggests that they should handle most standard resolutions in that range, such as 640×480@60, but the model in question may be intentionally picky.

[rpgwaiter]

I did some testing with a Dreamcast with VGA out and turns out the front port on the monitor is fried. There’s one on the back too and that one works great

• This reply was modified 2 months, 3 weeks ago by rpgwaiter.

[jmmliberty]

I have this same issue with a Zenith CRT presentation monitor – 800×600@60 only thru VGA (it also accepts 480i only thru YPbPr). I had been using an HDFury X4 to accomplish the 800×600@60 scaling, but that device stopped working. I was worried something was wrong with the TV, but I was able to use OSSC Pro to get 480i working on the YPbPr inputs. I’ve tried making custom resolutions for 800×600@60 with a borrowed Retrotink 4k, but I couldn’t get the timings right. I was using an online calculator that Retrotink suggests to come up with timing recipes. Since none of them worked, I’m not confident I understand all the active/backporch/sync/polarity numbers.

If I start by modifying the 1024×768 adv. timing by changing the active resolution to 800×600, do I need to change the synclen & backporch? I tried finding timing requirements in the Zenith manual, but it doesn’t say anything about those numbers or polarity. I just know it’s very picky about what kind of 800×600@60 it takes because everything I tried with Retrotink gave me the exact same failure message as the TV in @rpgwaiter’s post

[Kekstier]

i am very sure, your crt tv can only 15 khz c-sync… so one of the reasons is maybe your sync-combiner is deactived, you can able to activate this in output opt. under “HDMI combined sync” , so the rgb hv signal with 31 khz hv-sync converts to 15 khz c-sync!
By the way, this was the main reason, why a signal doesn’t arrived to a crt!

Second case is, your EDID information or handle is dump… you find this setting under “AV4 video in opt.” … set it to “10bpc RGB+HDR” as a try..

Third case, even you are don’t set the right input for your signal, when you send a signal from pc per hdmi, of course, the AV4 input channel must be activated (by the button 5 on the remote, for example)

[jmmliberty]

@Kekstier It’s a pretty uncommon set, and I’m a mere enthusiast, so I don’t want to “uhm, akchewally” all over the place, but this is a presentation monitor, and it absolutely operates at 37.9kHz! It up-converts 15.7 to 37.9kHz! I’ll attach a few screenshots of the service manual if you don’t believe me.

Side note – I took @marqs advice, modified the adv. timing of 1024×768 to match the basic SVGA timing, and it worked! I’m not sure why it didn’t work when I did that same thing with a custom resolution on the Retrotink 4k I borrowed, but OSSC Pro wins again!

[Kekstier]

Side note – I took @marqs advice, modified the adv. timing of 1024×768 to match the basic SVGA timing, and it worked! I’m not sure why it didn’t work when I did that same thing with a custom resolution on the Retrotink 4k I borrowed, but OSSC Pro wins again!

Yes, this would be my fourth suggest to modify the timings… i have respect to set up timings or give suggest for timings… but when it works, fine! I don’t know your tv has an exotic hv-sync, i never heard about 37.9 kHz sync timing… but presentation-monitors are very specified…

Of course, ossc pro wins… for my opinion, everything that was handle with “analog downscaling” ossc pro is a great winner! Best device for this purpose!

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