PS1 Psone no composite video output, S-video works (video inside)

[Anthonyg45157]

Hello all. New around here, was gonna joim AG but noticed it may be going down soon. Anyways as the title says IHave a psone(slim)that will not show video over composite. S video works as well as the flip up lcd screen. Sound also works fine. Any ideas? So far I've tried different cables and also confirmed cables are fine with another PlayStation. I've also swapped capacitors c550 and c551 from a working PlayStation to the one not working. From what Ive gathered c551 handles composite and c550 handles s video . After swapping s video still works fine however composite is still a no go.

Thanks for all of your help!

Anthony


Here is a video showing the issue

 

[segasonicfan]

Welcome to the site!

Well isn't that strange. Good news is the problem is not going to be your chroma encoder, so the fix should be fairly easy. I would inspect the jack for any corrosion on the pins. After that, I would inspect the traces for composite and specifically look at the 75 ohm resistor.
Have you tried with a different TV? These things aren't designed for LCDs so you might have a strange incompatibility issue going on.

If you want to go really deep with it, you can look up the service manual which is now dumped publicly and see where the composite signal originally comes out of the chipset. You can measure the output pin with a multimeter or an oscilloscope and see if it changes over time. Then trace back the circuit to the output until you find the problem.

Last option is you could actually make a composite signal out of S-Video. The two signals combine to make composite, so if you really had to it's not a difficult hack.

 

[Anthonyg45157]

Welcome to the site!

Well isn't that strange. Good news is the problem is not going to be your chroma encoder, so the fix should be fairly easy. I would inspect the jack for any corrosion on the pins. After that, I would inspect the traces for composite and specifically look at the 75 ohm resistor.
Have you tried with a different TV? These things aren't designed for LCDs so you might have a strange incompatibility issue going on.

If you want to go really deep with it, you can look up the service manual which is now dumped publicly and see where the composite signal originally comes out of the chipset. You can measure the output pin with a multimeter or an oscilloscope and see if it changes over time. Then trace back the circuit to the output until you find the problem.

Last option is you could actually make a composite signal out of S-Video. The two signals combine to make composite, so if you really had to it's not a difficult hack.

Thanks for the awesome reply! So far I've tried replacing the cap that I've read is responsible for composite video. I have tried different TV's including a CRT tv with no luck. Also I cleaned up any corrosion I saw ( very very little). However I may just keep this system and be happy it does Superior video output (S-video and rgb( to the portable Sony lcd))and quit worrying about composite altogether but just really like to figure this stuff out. Very neat you can make composite video from the s video signal I had no idea that was possible. Think I may leave this one as is so I don't break anything. I'm pretty new to all of this stuff including soldering. Thanks for all your help I may decide to dive a little deeper and if I do I'll update this thread with results!

 

[segasonicfan]

That sounds like the best route, composite sucks anyway XD
However, for future info, the way to go about this is "beep" (continuity test) the signal path first, then replace parts. Otherwise you just end up chasing your tail...

 

[danhans42]

If it's a second hand purchase, could it be that someone has cut the signal for composite video on the motherboard so cvbs is now just csync?

 

[Anthonyg45157]

If it's a second hand purchase, could it be that someone has cut the signal for composite video on the motherboard so cvbs is now just csync?

How would I be able to tell. It was a second hand purchase, I won it in an auction.

 

[danhans42]

Look for any cut tracks on the underside of the PCB. I can't remember exactly what the mod looks like but iirc it involved cutting a track on the PCB.

 

[rama]

Hey,
check for any unusual looking components around the small video encoder (IC 500 iirc) and/or solder residue.
A mod that puts CSync onto the CV line would have to cut the original CV signal and splice in the CSync signal.
I agree with @danhans42 that this is the most likely explanation.