SCPH-1002 BIOS corrupt.

[McMiller]

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.



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

[Administrator]

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.

[Yuri^Cybdyn]

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

[nocash]

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

[McMiller]

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.

[Administrator]

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.

[McMiller]

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.

[Yuri^Cybdyn]

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.

[Garru]

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.

Hello there
Bringing this old thread back to live (I hope you are still around guys )

I have scph-1002 (pure stock, never chipped previously) that looks like have exactly the same issue (at least playstation logo is corrupted the same way as in author’s photo)
It was working in my childhood about 20 years ago.. then I’ve stumbled upon it in my garage and decided to try whether it was working or not
I’ve never tested that it reads at music cds but my demo disk wasn’t booting… and then I’ve modded it with xstation (I was thinking that it’s just a dead drive and everything will work), alas situation didn’t change. Stucks the same way

Then I’ve googled for some time, and already thought that it’s a corrupted bios until I’ve found this thread

I’ve tried the test that you’ve suggested to author, pushed on gpu, tried the same with ram, and nothing flickers, it’s just stuck on the playstation logo as I’m not touching it at all

Soldering looks good across all motherboard, no sign of oxidation or corrosion

Any suggestion where to dig further? Any help appreciated

[nocash]

My oldest SCPH-1002 is now also saying "ed by ed by" instead of "Licensed by" when booting from CDROM. That is, when booting with the built-in BIOS, it does look exactly as in the first picture in first post above, and refuses to boot any further. Cleaning the lens and disc doesn't help.

When booting with my BIOS clone (from expansion port), it does display the correct text string "Licensed by Sony...", but instead fails to display the PS logo, and also refuses to boot any further.

On the other hand, when uploading an EXE file via expansion port, then everything seems to work fine, so the GPU and DRAM and VRAM seem to be intact. It's also showing the correct CRC32 for the BIOS rom, 86C30531h.

At the moment, I couldn't imagine why it's constantly running into the same "ed by" glitch. My best idea would be a problem with the sector buffer SRAM, or a modchip going amok when trying to apply a region patch, or whatever. I'll look inside later to see if I can find out more.

EDIT: Interestingly, the two quads with the two string halves "Licens" and "ed by" are rendered from two different texture pages (texpage=000Ch and 000Dh). That would hint on a GPU-related problem, but with the EXE upload all GPU tests are working perfectly. Hmm, might be a combo problem, like one GPU related bit or signal going unstable when the CDROM is simultaneously drawing too much power or generating noise.

[nocash]

The "ed by ed" issue seems to be popular on reddit http://www.google.com/search?q=psx+%22e ... reddit.com I don't really understand how to browse that webpage... from what I can see, the problem occurs on both PAL and NTSC consoles (despite of the different GUIs), and they don't seem to know how to fix it, except one person is claiming that it is caused by the IC305 cdrom decoder (citing somebody on twitter as "source", going by that twitter post, doing (something) with IC305 can cure all kinds of problems, supposedly including the "ed by" thing... but I couldn't say how trustworthy that is).

Looking into my own console. The power supply has the usual (half-)broken solder points on CN1 and C005, but repairing those doesn't fix the problem. The mainboard doesn't have any modchip installed. However, it does have several patches: Somebody has replaced one of the trimmers on the left board edge by a bigger one with weird plastic case. And also installed two large non-SMD resistors next to the 53MHz and 67MHz crystals (each with 402 ohms) (looking at service manuals, other PSX models seem to have 200 ohm in that place), and it looks as if somebody has replaced (or resoldered) the 53MHz crystal.

As for pushing down the chips. That's difficult with attached disc drive, cdrom disc, and spindle motor running. But it should be possible when building a small rack to mount the drive a few centimeters above of the mainboard, and also doing something about shorting the door open sensor.

[nocash]

I've converted the bios boot gui to EXE format and replaced the cdrom sector loading functions by a fixed logo and licence strings... so I could upload the EXE to the broken console without cdrom drive attached... doing that, it's now capable of properly displaying "Licensed by".

Then, while messing around, I've noticed that destroying one or more bytes in "Licens" string will trigger the "ed by ed by" error, even when running the code in emulators or on intact consoles.

The relation to the GPU is that the strings are converted to several small textures, in this ("reversed") order:
1. "pe"
2. "tertainment Euro"
3. "Sony Computer En"
4. "ed by"
5. "Licens"
If one of those strings contains any invalid characters (eg. FFh) then program code refuses to create a texture for it, and does instead re-use the previous texture, thus ending up with "ed by ed by" when "Licens" (or the preceeding space padding) is broken.

That seems to confirm that the error occurs somewhere in the CDROM Decoder chip or in the attached 32Kbyte sector buffer. Apparently after receiving the intact sector with successful error checking, and then losing some bits or bytes before forwarding the sector to the main CPU.

[MasterLink]

I'm running into this very issue on an SCPH-1001 I got from eBay. Were you able to determine if it was the CD controller or the 32K SRAM on the underneath side?

I'm going to try replacing the SRAM first, but I cannot for the life of me find another CD controller and would hate to buy yet another PS1 just to salvage its controller. So I'm hoping it's merely a faulty SRAM.