PlayStation Development Network

Hi there!

I want to flash the corrupted BIOS of my PS1 (SCPH-9002). I found this thread over Google but there is no info about what hardware @Xrider used for flashing. At first I ordered a 32-Pin Test Clip from Ponoma to avoid to solder many wires to the chip like Xrider.

Now my question is: What do I need to flash the BIOS?

I also got an Arduino Uno. Is it useful in this case?

How did your BIOS become corrupted? It's mask ROM. It shouldn't ever become corrupted. With that said, you can't flash it. You need to replace it or solder up a new chip with the same addressing, data bits, voltage and size (512 KB).

Shadow wrote: ↑February 24th, 2021, 3:31 pm How did your BIOS become corrupted? It's mask ROM. It shouldn't ever become corrupted. With that said, you can't flash it. You need to replace it or solder up a new chip with the same addressing, data bits, voltage and size (512 KB).

I think it corrupted after a while by the bad soldered Mod-Chip and parallel/expansion port from my time as a teenager (2001-2004). The PSX doesn't boot anymore and the screen is black with no sound.

This is the board of the SCPH-9002 and both were soldered to the BIOS chip in the right upper corner (the 32-pin one).



My solder skills as a teenager were bad and had use a chunky solder iron at this modification. Maybe I bridged some pins on the chip. It worked a while but failed some day and I just removed it after.

Most likely a blown fuse.

Shadow wrote: ↑February 25th, 2021, 8:17 am Most likely a blown fuse.

Are you sure? I've done a test a short while ago. The PSU is power on and the LED lights. When I get a bit pressure on the BIOS chip and press the lid switch the CD drive is run constantly. When I loose the pressure a bit it's get slower or stop spinning. The sound is crackling on every pressure and loosing. It's really odd.

The only fuses I can find in the service manual are for 250V. I check the service manual and PCB for SMD fuses tomorrow. Could be the PS601-605 fuses?

Edit: Okay I checked all fuses and they are all okay. But I'm a bit further. I re-soldered the BIOS chip and get a new result. Now it takes a couple of seconds (~5-8 sec.) then boot the Sony Logo correctly but without any sound and then the PS1 freeze. I think the board is broken. Maybe I get a used one on eBay or so. Or do you know a supplier that ships to Germany not so expensive?

Edit #2: Okay, I ordered now a "new" used PS1. Thanks for help anyway.

I know you managed to get another PS1, but I came across PSOne not too long ago that showed the same symptoms your PS1 was after you reflowed the BIOS chip. Alongside the delayed and silent Orange Sony logo screen that hangs, I noticed PS601 was blowing every time I replaced it as well. The system was completely recapped, deep cleaned, and inspected with no change in behavior.

I was able to resolve the issue by replacing the BA5947FP chip. Once it was swapped for a known good one from a donor board the console stopped blowing PS601, booted up correctly, and read every disc I threw at it. Hopefully this can help someone in a similar situation!

Btw, different revisions of the PS1 can have slightly different versions of the chip, physically though they all look the same. I replaced the BA5947FP with a BA5977FP from an older board and it did work, but it may be best to source one that matches the original. Here is an example of what they look like: