Frontend that displays properly at 321x240?

[boardjunkie]

Ok, I just got done hacking a flat face Sony Trinitron to accept RGB inputs.....that was the easy part. Everything works fine (as it did on a real arcade monitor), but the flicker is so bad it made it hard to look at. At a res setting of 320x240 the flicker is gone and everyhting looks good. But the MameUI window is only showing a small portion of it, making it useless. I tried installing Maximus, but even at the lowest res setting it offered there wasn't enough of it displayed to get the whole pix. Am I overlooking something or is this just not possible?

I started with a setting of 640x480, which was fine save for that damn flicker.

[ahofle]

Sorry to change the subject, but would you mind explaining how you hacked the TV to accept RGB?

[boardjunkie]

Looks like the original post in the main forup got moved here. Sorry for the redundancy.

From the schematic of the tv chassis, there was an extra set of RGB inputs on the "jungle" (main processing) chip that was not used. Unfortunatly, they were disabled in software, so I got nowhere there. I ended up just injecting the color signals right at the RGB outputs of the jungle chip. This is just before the color gun buffers, so .7vac signals weren't enough to get good color saturation. I built an RGB amp that bumps them up to somewhere around 2vac p-p (originally for a WG 4600 monitor). This worked great and everything looks right at the lower res. I combined the H/V sync lines via a couple of 180 ohm resistors (just a simple passive mixer) to produce composite sync. That gets shoved into the "video 1" composite video input. As long as you leave it set to Video 1, the sync gets to where it needs to be. The color inputs bypass everything else and go straight to the neck board via the buffers.

This was just an experiment to see what benefits (in theory) that Trinitron format offered. It did exactly what I wanted. Trini's are superior to std tv's/monitors because the tube and associated circuitry are propriotary to Sony.  So, in short, dark blacks, bright colors, and perfect focus/convergence. Normal TVs won't be any different from an arcade monitor....they're both made the regular way.

I installed MaLa yesterday but didn't spend much time trying to set it up since the flicker was making my head hurt. So I guess I'll need to do the setup on a VGA monitor to make it do what I want it to do then change the res after that.

The Sony will get mounted in an arcade monitor frame once I haul one of my cabs back here and get ready to finish the project. But, the TV deal makes for a nice portable MAME setup to haul around to parties and such. You can even use the TVs internal audio amps and speakers for even more simplicity. I might just get another similar Trinitron and do the same to that but leave it intact just for that purpose.

Just a quick question about MaLa, why does it bring up all kinds of stuff that doesn't exist in ROM form when you run it? I assume you need to do a scan to detect available roms and the game list is updated from there?

[ahofle]

Thanks for the explanation, that is the first time I've heard of anyone successfully hacking a TV that way.  It would be great if you posted a step by step instruction guide including pics seeing as how arcade monitors are becoming scarce and CRT TVs can be found at any thrift shop.

There is a way to filter the MALA list, although I couldn't tell you how.  Check the BYOAC WIKI on frontends...there are quite a few on there.

http://wiki.arcadecontrols.com/wiki/Front-Ends

[boardjunkie]

Its a pretty involved project, and not all TVs are the same. So the "rules" change on the fly. Anyone who can read and comprehend a schematic for a TV can have at it. Those who can't prob'ly shouldn't tackle such a project.

Plus, you need to build your own video amplifiers, which is really the key to getting the killer image quality. I'm finding out that my second attempt at the video amp is not gonna cut it. There's no control over black level or anything like that, it just brings the color signals up to usable levels. Translated....that means the colors are nice and bright, but some things get lost. Small edges of certain sprites fade off instead of remaining crisp.....like a blk level control turned too far down. The subtle get buried. So......#3 will more than likely be based on the LM1203 chip. That should get me where I need to be....

[elkameleon]

I have one of these tvs and I'm using component input to run it, would you be inclined to point me in the right direction as far as how you accomplished this? I know my way around electronics, so i'm not scared on that end. Even if you could link me to the chassis scematic, that would be cool too.

[kalars123]

hyperspin will run "and look good to boot" at any resolution your desktop is set at

[matsadona]

From the schematic of the tv chassis, there was an extra set of RGB inputs on the "jungle" (main processing) chip that was not used. Unfortunatly, they were disabled in software, so I got nowhere there.

Well, this makes sense since the european versions has an active RGB input throught the SCART connector (which makes everything much easier for us here). Guess Sony cut costs by using the same main board for all models.
I think it should be possible to activate the software. Have you tried the "secret" maintenance menues? But of course, if you have gone that deep in your solution to overcome this I might assume that you did...

[Gray_Area]

Why not run 336x240 or 640x240, instead?

[boardjunkie]

I'm not aware of any "secret" menus....unless yer just referring to the service menu via the sequence of buttons on the remote. I've been thru that.