SCPH-1002 BIOS corrupt.

BIOS, Controllers, Memory Cards, Serial I/O, Parallel I/O, etc.
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McMiller
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SCPH-1002 BIOS corrupt.

Post by McMiller » November 7th, 2015, 12:35 pm

Heya, sorry if this is in the wrong place. I'm not too sure where to put this query.
I have a SCPH-1002 which functions fine as a CD player, but does not load games. I suspect the BIOS is at fault.
Image
Image

Is there a way to restore full functionality to this PS1?

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Shadow
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Re: SCPH-1002 BIOS corrupt.

Post by Shadow » November 7th, 2015, 2:07 pm

Could be the DRAM or GPU. As a test, press down on certain IC's whilst the console is booting. It might cause it to flicker, and that way, you can pin point exactly where is going wrong. I myself have had a PU-8 with a poor soldered DRAM bank from Sony, so check those first.

Just be careful when you have your PSX open.
One false move and you will get a very nasty shock from the power supply.

As a tip, put some cardboard over the top of the PSU just in case your hand slips, or your elbow touches it.
Better safe than sorry.
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.

PlayStation Development PC: Windows 98 SE, Pentium 3 at 400MHz, 128MB SDRAM, DTL-H2000, DTL-H2010, DTL-H201A, DTL-S2020 (with 4GB SCSI-2 HDD), 21" Sony G420, CD-R burner, 3.25" and 5.25" Floppy Diskette Drives, ZIP 100 Diskette Drive and an IBM Model M keyboard.

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cybdyn
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Re: SCPH-1002 BIOS corrupt.

Post by cybdyn » November 7th, 2015, 9:38 pm

laser head is bad- it's a cause of problems. it's not BIOS)))

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nocash
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Re: SCPH-1002 BIOS corrupt.

Post by nocash » November 8th, 2015, 8:57 am

bad laser on a psx that can play audio discs and load the boot executable?

McMiller
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Re: SCPH-1002 BIOS corrupt.

Post by McMiller » November 9th, 2015, 5:12 am

I swapped the lens with a known working unit and it still fails to boot. I can rule out faulty lens then. I'll check out the mentioned ICs on the board.

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Shadow
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Re: SCPH-1002 BIOS corrupt.

Post by Shadow » November 9th, 2015, 2:54 pm

McMiller wrote:I swapped the lens with a known working unit and it still fails to boot. I can rule out faulty lens then. I'll check out the mentioned ICs on the board.
There's nothing wrong with the laser deck or laser circuitry...
Yes, check those IC's I mentioned. If you can't pinpoint the problem, I'll tell you some other areas to check.
Development Console: SCPH-5502 with 8MB RAM, MM3 Modchip, PAL 60 Colour Modification (for NTSC), PSIO Switch Board, DB-9 breakout headers for both RGB and Serial output and an Xplorer with CAETLA 0.34.

PlayStation Development PC: Windows 98 SE, Pentium 3 at 400MHz, 128MB SDRAM, DTL-H2000, DTL-H2010, DTL-H201A, DTL-S2020 (with 4GB SCSI-2 HDD), 21" Sony G420, CD-R burner, 3.25" and 5.25" Floppy Diskette Drives, ZIP 100 Diskette Drive and an IBM Model M keyboard.

McMiller
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Re: SCPH-1002 BIOS corrupt.

Post by McMiller » November 16th, 2015, 8:20 am

I had a feeling the laser assembly was fine, but i'm a sucker for potentially quick & lazy solutions.
Had some free time to take a look at the IC's and found no issues. Took macro pictures of the solder points to see if there were any poor joins but everything is soldered a-ok. Regardless I have a hunch that the DRAM is the one at fault here.

The pic's I posted above are from Colony Wars where it reaches the piracy screen, but every other game won't even get that far.

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cybdyn
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Re: SCPH-1002 BIOS corrupt.

Post by cybdyn » November 17th, 2015, 8:45 pm

bad laser on a psx that can play audio discs and load the boot executable?
Yeah, it's not 100% dead, and the problem maybe in lens, motor, or something else in mechanics, like it load data from center of the disc, but when heal go to out corner of the disc it fails.. especially it relate to FMV freezing, sipping frames,
anyway result is same, it works w/ CDDA disc well , cause of it need only 1x speed)) but, it fails to load games...

but sometimes, i saw problem w/ Memory on 1002, rusty throu-holes or memory ic and mother board.

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