PSX reads original discs but no backups

General PSX CD Troubleshooting, PSX CD-ROM Mastering and Disc Creation
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shawly
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PSX reads original discs but no backups

Post by shawly » August 8th, 2019, 11:08 pm

So I've bought a batch of three PSXes which were apparently broken so I could try to repair at least one of 'em.
Turns out none of the systems are actually broken, they just seem to have some disc reading issues.
The SCPH-1002 had a modchip in it (12C508A, probably an MM3?) and it had the issue that original discs played without any issues but none of my backups work, the Playstation logo pops up and then it's stuck on that screen.

I've removed the mod chip in hopes that it is the culprit and replaced it with a PsNee.
Sadly the same problem persists with the PsNee. I guess the laser isn't able to read the backups (Verbatim CD-R) properly.
I can verify that the discs are not at fault, my PS2 with a Modbo is able to read them without issues and so is the SCPH-9002 which also has a modchip in it.

Because it's an SCPH-1002, I thought that the plastic sled is probably the issue here. But it turns out that the sled isn't a plastic one, it's cast aluminium. Guess it has already been replaced, since all 1002's have plastic sleds, right?

Anyway, is there any place where I can get a new laser? Or are there any other (longer lasting) fixes for this issue?
I could sacrifice the SCPH-9002 since it seems to be able to read backups properly. But I'd rather fix all of the systems.

rama3
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Re: PSX reads original discs but no backups

Post by rama3 » August 9th, 2019, 2:02 am

Many 1002 series have an ACM drive (with the metal sled), but that doesn't mean too much.
These drives still suffer from friction related material loss and thus, misalignment.
They're just not as horrible as the full plastic AAM drives.

It's possible that your drive starts working when you slightly increase the laser diode power.
Check Google for guides on this :p

Also listen to the sounds the drive makes.
The laser right now can read a bit of data, making it reach the PSX logo screen.
If you tweak the laser pot, make sure the drive doesn't create a ton of new/different noise.
(If it does, you applied too much voltage.)

shawly
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Re: PSX reads original discs but no backups

Post by shawly » August 13th, 2019, 5:56 am

rama3 wrote:
August 9th, 2019, 2:02 am
These drives still suffer from friction related material loss and thus, misalignment.
It's indeed an ACM and since there is no grease on the sled nor the gears it's highly likely to have worn out. That would also explain the rattling sounds it makes.
I already tried adjusting the pot but I can't achieve a pot position where I'm able to read backups.
I ordered a KSM-440BAM from Aliexpress since I've given up on trying to fix this drive. Maybe I'm luckier fixing the other two systems.

rama3
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Re: PSX reads original discs but no backups

Post by rama3 » August 15th, 2019, 8:42 am

Good call.
The BAM is most likely new old stock and it'll work just fine in the 1002 unit.
Just make sure to swap the top drive cover, removing the grey one and placing your old black one.
If you've modified the pots on the mainboard, revert them to their original position.

Just so you know, I've tried to devise a universal method to fix the ACM drives.
It is possible to do a little bit good to many of them, so that they'll read well enough to play a game or two.
Never more than that though. It seems there is no "easy" fix for them.

shawly
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Re: PSX reads original discs but no backups

Post by shawly » August 17th, 2019, 9:03 pm

The laser arrived today, how do I know if it's old stock or a clone?

rama3
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Re: PSX reads original discs but no backups

Post by rama3 » August 17th, 2019, 11:23 pm

They don't clone these, I don't think.
The effort for that wouldn't be worth the development costs, even back in 2001 or so when BAM models were current.

But if the drive looks similar to your ACM, no weird plastic remains everywhere and such, then it's fine.

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