SCPH-1000 - Sound issue

[PSX_ISO]

Hi everyone,

I'm a long time PS1 enthusiast. Used to be on an old message forums way back in the day uploading ISOs to public FTPs. I believe the message forum was PSX-ISO. Maybe someone remembers this web forum?

I am in need of suggestions for solving an issue with a PU-7 SCPH-1000 I recently acquired. Seller claims it was never used. The console itself is mint, spindle is perfect and reads games/cds flawlessly. Pretty cool! Unfortunately the sound is call screwed up. Heavy glitching, missing many notes. CD music isn't effected (really bad hiss is there), but game music is really bad as well (just like the intro).

I made a post here: https://www.reddit.com/r/consolerepair/comments/l3k8jv/schp1000_launch_ps1_startup_sound_glitches_heavy/

Video of the issue: https://imgur.com/a/4dwDCQO

It has been suggested that the SPU chip (IC305) may be to blame. I plan on taking a look at it tomorrow. It is suspected the cold solder joints could be causing this? I've been recommended to apply pressure to the pins. Has anyone ran into this issue and could suggest clues on what to look at closer?

Here is a closer look at the PU-7 along with chip identification: https://www.ifixit.com/Teardown/Sony+PlayStation+Teardown/128089#s250690

Thank you for the help. I have added a few photos of the unit, I'm hoping others will appreciate it

[Administrator]

Nice SCPH-1000. Looks virtually brand new

As for the SPU, press down on the known chips that process audio and see if it comes back. If it does, you've got a cold-joint. Flux up the pins with no-clean flux (I highly recommend CIF flux from France), use a bevel tip (also known as a single-flat tip) with the correct pitch, add a very tiny amount of leaded solder to that bevel-tip so it cups the solder and then drag-solder away. You don't need to, but you can clean the board after by spraying the area with alcohol (IPA) and using a a soft brush to breakup the flux. Rinse it a few times with IPA after and let it dry. Should be good to go and look brand new still.

It goes without saying that when you do press down on the SPU and related sound chips, be very careful around the exposed power supply.

[PSX_ISO]

Hi Shadow,

Thanks for the suggestion. I have the unit disassembled now. It is 10/10 mint on the inside. Not a fingerprint - looks I'm the first in there since new.

So far flexing the board or putting pressure on chips has not fixed the issue just yet. I am wondering if this unit never worked right and that is why it has remained "new" all these years...

Edit - another two hours of troubleshooting. I have reflowed a few ICs, removed the board and flexed it in various directions. No change in sound, no breakups. Too bad there isn't a schematic and I can focus on just this signal path. Based on not being able to have difference in any physical manipulation I suspect it may be an IC.

I have also examined and probed the PSU. It is healthy, putting out the proper ~7.6v (7.72v) and ~3.6v (3.55v) DC.

I've further noticed the problem only seems to be with the lower frequencies on the audio spectrum.

Similar complaints:
https://www.reddit.com/r/psx/comments/fg5rvs/ps1_boot_sound_static/
https://www.reddit.com/r/psx/comments/gaup9h/original_psx_audio_issue/

[TheShadowRunner]

@PSX_ISO , off-topic but did the serial on the mobo (sticker located on Memory card module, or shielding) match the one at the back of the system ? Somehow serials were mismatched on early models it seems..

[PSX_ISO]

You are right, but the serial is on the top metal cover. It does not match, although close.

I'm throwing in the towel. I replaced the SPU IC with one from a 5501 along with the RAM. Didn't solve the issue (new chip did not work). Old ICs back in, problem remains.

Anyone have a PU-7 for sale?

[Administrator]

Could be an issue with the amplification circuit or even a faulty capacitor.

[PSX_ISO]

I ran around and replaced a few 10uf caps, no difference. I do have a collection of new non SMD type caps for this. I suppose I could just do a full recap... Any suggestions on where to look?

I'm wondering if the 5501 SPU chip would have worked and I just did not seat it properly... There was just no sound at all.

[~PSXLoVeR95~]

Check if the PS plays the CD audio correctly (on cd player menu)... and if so, the problem should be the SPU.

Maybe you replace the CXD2922Q with a broken one.

[PSX_ISO]

Check if the PS plays the CD audio correctly (on cd player menu)... and if so, the problem should be the SPU.

Maybe you replace the CXD2922Q with a broken one.

Yes, CD Audio works perfectly. I can tell in a game if it is playing a .wav audio or if it is generated by the chip on board.

I do not think there is much documentation but can I use a SPU from a different model? I doubt it...

I tried with a CXD2925Q and I got no sound. It may have been that i missed a leg to solder on, not sure. Same for the ram as well. The PS board does not care very much for high heat.

[~PSXLoVeR95~]

So, the problem is absolutely the SPU.

But that's strange...

Check the solder and use a lot of flux.

[PSX_ISO]

I have reflowed it many times, I have viewed it many times from my camera phone to make sure pins were OK.

I put in a diffrent model SPU Ram, same issue. I put in diffrent model SPU just now and now there is no video. Will pinout later but I am guessing it doesnt like this replacement SPU.

[PSX_ISO]

Made a last video of the issue. Pretty much more of the same, taking any ideas. I'm putting way too much time into this but I don't like to give up without a fight.

I found a seller that has a for parts SCPH-1000 that just has a mildy poor case as well as a bad laser. This SCPH-1000 model seems to cost a lot more than the USA SCPH-1001 that I can buy locally for $40 with all cords, controller and a game.

[Administrator]

Ah, I just watched your video. Check the four DRAM chips

[PSX_ISO]

Ah, I just watched your video. Check the four DRAM chips

Funny you say that, I never did much with those four chips. Not even a simple reflow. I just nailed them now with a reflow and nothing :/

What made you suspect them?

[Administrator]

The audio is usually transferred from the BIOS to DRAM and then via DMA to the SPU RAM. Hmm, this is a bit strange then. I don't know how to fix the board without having it in front of me and visually inspecting and testing things.

[PSX_ISO]

I appreciate the feedback. I have abandoned trying to fix this particular board. I attempted to bypass the SPU and have it just be a CD player but I realized that although it was booting past the white Sony boot screen into the main menu, it actually was freezing as soon as it got into the menu. I have no idea at what point that began to fail but it was probably when I messed with the DRAM.

I have since ordered a SCPH-1000 from Japan that has a bad laser. The seller confirmed that everything else was working. I'll use that board and possibly swap the RCA/Svideo header assembly as this one is mint. Should have an update in ~4 weeks or so when it finally arrives

[Administrator]

Send me the faulty PU-7 if you don't want it. I'll see if I can find the problem and repair it. I'm interested to know what the issue with it is

[PSX_ISO]

Sure I just might do that.

I just recieved my second SCPH-1000 today that has a "bad laser" but good sound. It had rusty finger prints on the inside.

Same problem as my other SCPH-1000. Turns on but all inputs freeze at the memory card / CD Player selection screen

It doesn't even seem like it is trying to read. Spins the disc but the motor to move the laser across the CD doesn't move.

Inputs work for a few seconds then stop. If I am able to get into the memory card screen input works... Of course my "brand new" laser from the first SCPH-1000 that used to read flawlessly does not read at all... So frustrating another bad PU7!!!

Edit - further testing. It is not appear to be a loose solder joint. Every ~15 or 20 seconds it responds to input from the controller in the main (memory card and cd player selection) and CD menu for roughly one second. In the Memory card menu it works flawlessly without interruption.

[Administrator]

I believe the controller inputs stall (due to poor programming in this version of the BIOS) if it can't detect a drive (in this case, the photo diode can't be detected so it thinks there is no drive). I replied to your other thread, but replace the motor controller and optical block with a different one.

[airfoxtwo]

have you tried it on another tv? Could be your input connection. Or the sound chip inside the ps1 is on the fritz.