PSOne issue

[Squaresoft74]

Hello,

I have some issue with a PAL SCPH-102 PSOne.
The console was never disassembled before i get it and is is a pretty clean state.

It doesn't boot any game, sending me either to the "Please instert a Playstion game disc" screen or the the CD player menu.
I first thought the drive was faulty so i tried with a few other BAM drives i have and know to work fine with other machines.

Same thing, games won't boot.
This machine's BAM drive also works fine on other consoles.

When i'm playing a CDDA disc or CDDA tracks from games' discs, i noticed that the sound is kinda saturated.

No such sound issue with the bios startup.

Could there be something wrong with the motherboard itself ?

Thanks

[Administrator]

Yes. It sounds like one of the pins on the CD-ROM MCU is lifting. Try pressing down on the IC slightly whilst it's playing CDDA audio and see if it changes back. If it does, you'll need to find the bad pin and re-solder it.

If this was an older PSX board (such as a PU-8), it'd be easier to fix because the components aren't centralised.

[Squaresoft74]

Thanks Shadow i will check that.
Sorry for the noobie question, but can you point where that chip is located ?

Is it the C 2060..... one in the middle ?

[Administrator]

Thanks Shadow i will check that.
Sorry for the noobie question, but can you point where that chip is located ?

Is it the C 2060..... one in the middle ?

No, I that's the "Motorola HC05" (mechanism controller).
MC68HC05G6-SC430942PBEB1 = SCPH-100/103
MC68HC05G6-SC430943PBEB1 = SCPH-102
MC68HC05G6-SC430944PBEB1 = SCPH-101 (this is the one in your photo).

The one you're after is CXD2938Q (IC732). This is the CD-ROM Digital Sound Processor, Digital Servo Controller, CD-ROM Decoder and Sound Processing Unit in a single IC.

[Squaresoft74]

Thanks for the details Shadow but still no go pushing that chip.

Now something interesting (and no kidding).
If i'm warming up the motherboard using a hair dryer, it's boots game fine and the "saturated" sound when playing CDDA is completly gone !

When everything gets back to cold, problems come back aswell.
A defective capacitor somewhere ?

[Administrator]

Maybe, but I doubt it. There is a lifted pin or component somewhere. You need to press around the board until you can find where that is happening. Once you find it, you'll need to either re-solder it or reflow it using hot air. Otherwise, try pressing down on some capacitors if you think it may be one.

[Squaresoft74]

Still no go when pressing but warming up this specific area with the hair dryer does fix the problem temporarily:

[Administrator]

That's your voltage regulation circuitry. The heat would disperse however, so it might be something borderline of these components. I can't help you any further unfortunately with this issue.

[Squaresoft74]

I'll let that board aside for now until i get the proper tools to check and maybe replace those capacitors and see what it gives.
Thanks anyway Shadow.

[nocash]

What do you mean by saturated? For audio, that would usually mean clipping the min/max levels, did you mean just that? Myself, I could identify that effect only via oscilloscope, not by bare listening (I am no musician).
Anyways, on SNES console, if you replace the audio amplifier's 9V supply by a 5V supply, then the sound final output will get saturated like this (again, I can't hear much of a difference, apart from volume dropping maybe):

Code: Select all

  Amplifier Output at 9V:                 Amplifier Output at 5V:
     /|   /|   /|   /|   /| -8000h +2.5V     _    _    _    _    _
    / |  / |  / |  / |  / |                 / |  / |  / |  / |  / | -3XXXh +1V
   /  | /  | /  | /  | /  |               _/  |_/  |_/  |_/  |_/  | +3XXXh -1V
  /   |/   |/   |/   |/   | +7FFFh -2.5V

If anything like that is happening on your PSone, it might be the same effect, ie. caused by low supply voltage for the audio amplifier.

Warming up the PCB/components might in fact 'fix' problems with damaged capacitors. Are the five big capacitors still looking "flat", or is their surface blown up like a balloon?
Other ideas would be checking for broken solder points, or measuring the different supply voltages (psone service manual might help to find which voltages exist for which components).

[Squaresoft74]

You can see and hear the problem here.
This completely disappear when warming up first and games boot straight.

The five big capacitors are still looking "flat" so no physical hint on that side.
I don't have the proper tools and replacement to desolder them right now.

Other ideas would be checking for broken solder points, or measuring the different supply voltages (psone service manual might help to find which voltages exist for which components).

I might do that, thanks.

[nocash]

Uh, no tools to desolder, means no soldering iron at all? If you had one, you could try to warm up the metal case of the capacitors with the soldering iron (but better not too much/too long), maybe that would help to track down which of them is bad. For replacement, you won't need SMD capacitors, you could also wire almost any other kind of capacitor to the solder pads, the voltage rating should be same (or higher) and the microfarad rating should be at least more or less same as on the original component.

Btw. unrelated to your issue: I've just reassembled my SCPH-5502 today, and found it to be not working anymore. One tiny capacitor (1000pF between power supply pin 1+2) looked as if it would have leaked acid like a battery, and... three small inducturs and six small capacitors somehow dropped off from the PCB bottom side, near the A/V multi out socket. Did that ever happen to anybody else?
It might be related to improper storage conditions (I've had the PU-18 board laying on a heap of junk for a couple of years, and maybe also stacked some heavy books or other stuff on it, but didn't imagine that it could cause the SMD components to break away). I've removed the rotten 1000pF capacitor, and also left the other six missing capacitors uninstalled for now, and bridged the missing inductors (composite, dcout, and one of the two audio signals) with wires, and now the console is back alive.

[Squaresoft74]

Good idea about gently using the soldering iron to warm up the capacitors, i didn't think about that, thanks !

I have a ZD931 soldering station but need to get a thinner tip, mine is a bit too big and old.
I recently chipped one of my PS2 Slim and it was a pain with it.

I was thinking about getting something like this to replace my ZD931.
I know it's Chinese stuff, but should be way enough for my occasional needs.

Did that ever happen to anybody else?

Not so far on my side.