Post
by Administrator » April 28th, 2015, 4:31 pm
I find it's easier to get an old CRT TV and drive the cathode RGB guns directly from RGB out of the console. Problem is, you need an amp to drive the cathodes because RGB from a PSX is ~0.7V, where as the cathodes require a bit of a higher voltage. The cathode voltages depend on the TV, so use a voltmeter to check and try to match them with the amplifier. It will work on a lower voltage, but the picture will be dim. It's best to add potentiometers to the back of the guns so you can fine tune them according to your likeliness.
As for the sync, just feed the C-Sync signal to the RF, Video 1 and Video 2 pins on the driver IC. That way, as soon as you turn the TV on, no matter what channel it is on, it will always display your picture. This mod will now render the TV as a dedicated RGB TV only, so unless you add a bunch or switches or make yourself a circuit that will use something like an ATMEGA328 with mosfets to control everything via a single button, it's stuck like that.
I've also found you can drive the on screen display chip (aka "Jungle IC"), but most of them use digital RGB and not analog RGB, so you wont see gradients for example.
I have a really big and old NEC CRT that I will try to get working using the direct gun driving method. I will start a worklog so that others can see how to do it.
*UPDATE*
Here we go:
http://www.psxdev.net/forum/viewtopic.php?f=62&t=723
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.
PlayStation Development PC: Windows 98 SE, Pentium 3 at 400MHz, 128MB SDRAM, DTL-H2000, DTL-H2010, DTL-H201A, DTL-S2020 (with 4GB SCSI-2 HDD), 21" Sony G420, CD-R burner, 3.25" and 5.25" Floppy Diskette Drives, ZIP 100 Diskette Drive and an IBM Model M keyboard.