NFG Games + GameSX

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A common problem with creating portable PSTwo systems is that the screen turns green after 20 or 30 minutes.  There is now a permanent fix.

The short:  
Lift the lower end of each of the CV53, CV54, and CV55 SMD caps on the PSOne LCD board.  
Connect the R G and B inputs directly to the lower end of these caps, with CV53 to Red, CV54 to Green, and CV55 to Blue.  
This bypasses a bunch of extra circuitry, which presumably causes the green tint effect.
Enjoy!


The Long:

First off, a little background... I personally have seen the green tint issue, and on the exact same PSTwo and PSX screen used in this example, the effects were noticeable after 20-30 minutes of play. I've read segasonicfan's thread on the BenHeck forums, which had eastsider_1's fix for connecting the R and B lines to +5v, and segasonicfan's revised method of jumping R and B together, which did help me, but I found that a bit annoying and figured I could do better.

I started looking at the screen's PCB, checking datasheets for the main IC's and tracing signals. I was interested to find that the LCD signal processor (Panasonic AN2526NFH) required only a 1uf capacitor on each of the RGB lines, but that Sony had thrown in a bunch of other components - extra caps, IC's, signal switches, resistors, transistors, etc. I figured part of that was to be able to switch between RGB and te external composite input, but of course I didn't need that. I found 3 SMD capacitors, marked as CV53, CV54, and CV55. These are inline with the red, green, and blue lines, respectively, and are rated at 10uf.

Basically, at this point I thought, "why not bypass all the extra crap?" so I did, and it works! I ran my PSTwo on this screen for over 2 hours without experiencing the problem.

To fix this problem, all that's required is to find those 3 capacitors, lift one end up (the end that doesn't connect to the signal processor), and connect 3 wires from the input connector directly to those 3 caps! I didn't touch the sync signal at all, and I didn't disconnect the RGB signal from the original circuit, save for lifting the 3 caps.

The only side effect I've noticed is that the picture is a bit brighter than usual, even when the brightness is lowered all the way.  Also, this mod may affect the ability to use the external video input, but I didn't test it to find out.


Now for pictures:

These are the 3 caps in question. Basically, I've removed them and resoldered them upright, so as to only connect on one end. I then soldered the 3 wires to the PCB input connector. Note that I've lifted the lower side of the cap up, so that it's standing only on the upper connection of the footprint.

{{:ps2psxlcd:crw_1370.jpg|}}


Here's the other end of those wires. I used 30ga insulated magnet wire for this, but you can use whatever you want. On the input connector, pins 4, 5, and 6 (counted from bottom up) correspond to red, green, and blue.

{{:ps2psxlcd:crw_1371.jpg|}}


Here's Okami after about 90 minutes:

{{:ps2psxlcd:crw_1398.jpg|}}


Any question or comments, please post in my original thread [[http://forums.benheck.com/viewtopic.php?f=7&t=32915|here]].  Feel free to use this info anywhere, so long as credit is given to Simon Allan, and so long as the info is distributed freely.