Help Weird :Psone PAL with RGB cable display image without color

hello i have playstation Psone PAL

happen weird problem when i conect the psone using scart rgb cable
the cable rgb is good quality i buy from retrogamingcables uk store and is wired as " Sync on Luma "
i dont think is the cable fauly because i try the same rgb cable with PS2 fat and other Psone and i see color on picture

i turn on the console and the picture is like grey black and white no color

"" but what is strange is with console turn on if i unplug the cable from back of the tv and plug it again is show color again is very strange this.. ""

console have chip installed the " Onechip " and i still do the color mod fix
by the way before installe the chip and the color mod fix
i already have this problem image with no color when using RGB cable


this only happen when i use scart RGB , av composite cable no have this problem show color

i try another tv led and old tv crt and still no color when i use RGB
only show color when i unplug rgb cable form the back of the tv and plug it again


i even try clean the av port on back of the psone console
and still have this problem having no color on image

i check if any damage on montherbord.. and i dont see nothing to the eye
maybe some capacitor is dead ?

if someone can help on this thank you all

 

It sounds like it's not switching over to RGB.

Getting a B/W image with a cable wired for sync on luma is what you would expect if the TV is selecting composite input (which is now luma) rather than the RGB.

 

the picture looks nice a sharpe like rgb mode but evertiem i turn on the console tha image is black and white , and the strange thing is with console turn on if unplug the rgb cable and plug again then is show color i dont understant
i try same cables with other ps2 fat and other psone consoles and working nice so must be something about this console
maybe some capacitor close to av port i see 3 silver ones i do little search on net and psone have this capacitos for RGB lines one for luma other forcompsite etc i dont no too mutch about electronic especs.. maybe some of this capacitors need replace ?

 

i try on crt old tv and happen the same show black and white so i think is not the cable is working on ps2 fat and other consoles too

 

@TriMesh already told you what the problem is. Your TV is not switching to RGB mode.
The brief time it shows color, this is actually RGB mode.
Try to force your TV to RGB. Oftentimes, there are several "AV" input modes. One of them is RGB.

(The black and white picture is sharp because it's just the Luma signal from S-Video, ie: Composite without color.)

 

ok like i say is strange because i try other psone consoles with same tv and samr rgb cable and i dont have this problem
and i try this cable and with old tv crt and same problem happen so you sure is my tv is the problem ?
thanks

 

must be something on this console i dont no i guess
i have other consoles and cables are wired sync on luma too and i dont have this problem with no color

 

The other possibility is that the switching voltage is too low - if you have a meter, then try reading the voltages on pins 8 and 16 of the SCART plug with it connected to the TV.

Pin 8 should be between 9.5V and 12V to indicate 4:3 aspect ratio (5V to 9V will also work, but will select 16:9)
Pin 16 should be between 1V and 3V to select RGB input - if it's less than 1V it will cause the problems you are seeing.

 

Any solution to this? I have absolutely the same problem...PSone, Sync on Luma RGB cable from retrogamingcables and I only get color when I unplug the RGB cable while the PSone is running.

 

Yes, read the post above yours.

 

I know that the voltage on Pin 16 seems to be too low. But is it the power supply or the console itself? Also it is above 1V when I measure it after booting. That seems to be the reason why it shows color after reconnecting the RGB cable.

 

Can you open the scart end of the cable, so we can see how it's wired. Specifically if there's a resistor on pin 16

 

You could try swapping r1 with a 75 ohm resistor.

 

180 Ohm is a correct value and I don't want to fix what's not broken. The cable is most likely not the problem as already stated by gamer2000. It has to be either the power supply or the PSone itself. Unfortunately I don't have a replacement for that, so I hoped someone had the same problem and could tell me what to replace.

 

The value of 180,with an input of 5v and the 75 ohm termination resistor in the TV will give you just over 1v. Changing for 75ohm will just mean you get half the input (so with 5v, you get 2.5v). It just gives you some leeway.

Im not blindly guessing. It's not the power supply and its unlikely to be the console, but you can check... Just measure pin 8 voltage and let me know what it is. As the console should be putting out 5v ish, that goes to pin 8 and then the resistor brings that voltage down for pin 16. But my suggestion was so the voltage is increased on pin 16 as this seems the issue..

If it's the console, pin 8 won't be 5v and that with the 180 ohm resistor is giving too lower power to pin 16 to switch. My suggestion of 75 ohm would work on all other consoles and probably this one too.

 

Thanks for your reply. But how do you explain, that the TV switches to RGB mode after reconnecting the RGB cable? To me it seems that the voltage on pin 16 is too low when powering on the PSone but high enough when running (measured 5V at pin 8 when the PSone is running). This points me to a problem with the power supply or a voltage converter in the PSone.

 

OK, so is this an accurate description of what's happening?

1) You turn on the console with the cable connected, the TV displays in monochrome and the voltage read on the pad marked VCC is approximately zero volts.
2) You then disconnect the RGB cable
3) When the cable is reconnected, operation is correct and the VCC pad rises to approximately 5V

This sounds like something in your TV is tripping the protection circuit on the AV port 5V line. This line has always had protection on it, but in the later units (SCPH-900x and PSone) it was made latching - I.E. once the rail had tripped the only way to get it to work again was to completely remove all load from the port. Together, the 180R resistor in the lead and the 75R load resistor inside the TV would present about a 255R path to ground, which is certainly low enough to prevent the circuit from resetting.

 

Yes, that is exactly what happens. Before reconnecting the cable the voltage at VCC is around 100 mV and the image grayscale. After reconnecting it is around 5 V and the image is in color. But it is not only with my TV, I also used a Scart2HDMI converter and it's the same behaviour. Any idea what triggers the protection?

 

It's basically a current limit. It's possible there is a cap on the aspect ratio switch line and the inrush current on powerup is dragging the line too low - and the load from the RGB/Fast blanking input resistor is subsequently preventing it from going back up again.