Green debug psx won't read game discs. Motherboard issue?

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[TD]Hi, everyone. Here is my problem.
I have an old DTL-H1202 psx, a green PAL debug model. It was working correctly until months ago.
One day I was playing with a game then I turned off the console when finished and leave it there for about 2 months(didn't have much time to go on playing), then one day I turned it on to continue playing that game but... the console didn't recognize any game discs.
If I insert a game disc, this spins than stop, than spins again, then stop etc... the console boot up and then go to the memory card/audio cd selection screen but the PS logo doesn't even appear.
After I bought the console years ago I've changed the optical group with a new one(the model from the latest PSOne) and set the bias value, everything was working fine back there until recently.
I've tried changing the bias values and I've also tried a different optical group but nothing changed: the console doesn't recognize any game discs, could have happened something on the motherboard?
Audio cds are played correctly.
Hope someone here can help me because I don't know where to get some more information on this issue.
Thanks.


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They all have a crappy laser assmbely, you can ether replace it with one from the 100x playstation, or use one from the PSone(the slim one)

 

Inside the console there is already a psone laser. The same laser works correctly on a psone I have. And the laser of the psone doesn't work in the debug model... So the laser works.

 

I have this problem with my SCPH-5500, I have been told that it may be capacitors, it seems to be rather common with pre SCPH-7000 units, those are the same ones that have potentiometers on the mobo.

 

What capacitors do I have to check? And how do I check if one is not working correctly? Can I use a tester?

 

Problem can be the incorrect bias value on the mobo.
Without an oscillator isn't simple. Try with this guide.
http://dogbreath.de/PS1/LaserAlignment/Laser.html

 

But the console was working fine before I tuned it off the last time I was using it. And after that period I just turned it on but I didn't touch the potentiometers on the motherboard.
Also there are 3 pots but what is the value for the third one( the one by itself on the right)?

 

I can't help you very good because i don't have a DTL-H1202
Im very sorry.

 

I've tested all the capacitors on the board, the 4 ones circled are not "responding" to the tester, they are not "charging".
http://imageshack.us/photo/my-images/198/img20120915183716.jpg/
The other two just below do respond to the tester and they are the same, on all six there is written 10 216 or 10 z16 I don't understand f it's a 2 or a z...
So... are these 4 the problem?!

 

The PS1 board is very slim and due to that is prone to flexing. Flexing cracks the solders causing the pins of the QFP chips to loosen up causing random problems.

PlayStations are not the kind of machine known to have capacitor problems. Specially the early ones. I don't think I have seen a PS1 with bad capacitors ever.

 

Yeah, capacitors used for psx are great quality (nichicon the top )
Continuity test is useless for capacitors, and the aspect of circled ones in the photo seems ok.

 

Sounds logical, many PlayStations with this problem including both of mine have mild to moderate oxidation on the plates above. That generally is a sign of overheating.
Edit: Where would I find a broken connection that would cause the disc authentication to fail on an SCPH-5000 after the switch to 2x speed but before the black screen?
Edit2: Oops, it is a 5500

 

Check the resistors around the DSP chip. Is that a PU-18 board ? You might want to hot air the region around the DSP and interface chips.

Also check for cracked or corroded resistors. Sometimes they corrode the corner, cutting the current flow, causing the console to fail. Particularly if the component has been exposed to "finger grease".

 

Ok guys, everything can come in handy, but what about those capacitors that don't respond to the tester?

 

So your playstation seems to have the same problem as mine...

 

You should NOT be testing capacitors with a ohm meter. If you expected any answer about it. Also to be able to correctly probe capacitors you need to remove it from the circuit.

 

I'm not an expert of these things. I've just read on some websites that I can test them with a normal tester and see if they "charge"... -_-"
Anyway, I can still test the resistors, right? And if so which ones should I test?
Anyway I don't see any desoldered/moving pin from all the big chips on both front and rear of the motherboard.

 

Well you won't damage anything by using the ohm meter but what happen with the information you get from all the testing, it's useless and won't help you in repairing unless you have a good idea of how it works ...


For example, hypothetically if you had a mute left audio channel on the PS1 you could use the ohm meter to diagnosis where the audio circuit is interrupted or (in this case you would measure the capacitors to check if any of them is short-circuited). Now that's a situation where measuring the capacitors are useful. I didn't meant to discourage you if it did look like that. edit: Curiously, the capacitors you circled on your picture ARE part of the audio output circuitry.



I can suggest you put the system together in a manner you can have the bare board exposed while you can put a disc on the laser and see it spin. You can try to gently push down the large chips at the CD section of the board and see if it starts working. If it does, then the problem is cracked joints.

 

Te l'avevo già detto prima che il test che avevi effettuato sui condensatori serviva a poco e a nulla
A capacitor can be damaged because don't charge at all, but with your tester in ohm mode you can only check if charge. Not if charge "correctly"

 

I also forgot to mention that mine CAN read audio cds, I don't know for sure but I think debug units are capable of that too, check that.
I have had 30+ PlayStations of which about 10 ever needed repairs, this problem happened to only 3 of them, in 1 case it was a bad spindle motor (SCPH-1001), another I gave up and returned the unit (SCPH-1001) and this one I have now (SCPH-5500). BTW yes it is a PU-18 board. What is odd is that I barely used it since I had 2 good units, I was planning to sell it when a last minute test it wasn't reading game CDs. What ever happened had to be during the 6 months it was in the closet.