PS1 7501 fuse/power issues?

[kchung]

I tried to install a Mayumiv4 modchip on a 7501 with a PU-22 board with some magnet wire and while testing I must've caused a short somewhere and I lost the PS604 fuse (no beep on continuity check).

It was the middle of the night and I wasn't sure what to do so my hunch was that PS604 was broken so I bridged it temporarily to see if it would power on and it did.

So I went to microcenter and bought some fuses 2A fuses (http://www.microcenter.com/product/4256 ... t_-_5_Pack). Soldered it onto PS604.

Turned it on and during testing things the motor would spin up but wouldn't boot into a game. I don't remember exactly where it got stuck and I figured that the game issues had to do with the cd drive (had previous issues with it and was tweaking the pot).

Then after a few tests (with the modchip on), the motor spun very fast and then stopped spinning. After this point the PS1 now gets stuck on the white logo screen after a slow boot up process. There's also no sound.

At this point, I figured PS603 was blown but I replaced that with a glass fuse and the motor spun, and there was sound for a bit before it went back to being stuck on the white logo with no sound and no motor.

At the time I had a multimeter with a dead battery so I could do some continuity checks but I have a working multimeter now so I can check some points if need be.

What could be the issue here?

Pics of boards here:

I'm not really sure what to do here so I could use some pointers about what to look at. I got this console off craigslist for $10 so it's not a huge loss if it's dead but I was kind of hoping for an easy win.

I originally made the modchip with a Pickit 3 and a PIC12F508. I accidentally got a surface mount chip so it's soldered onto a breakout board.

At the moment I resoldered PS603 on the board since the glass fuse is kind of annoying and I'm not entirely sure PS603 is broken anymore since it gets stuck on the white logo with either the SMT fuse or the glass fuse.

[rama3]

From your description it sounds like you blew the CD DSP.
But before writing the board off, obviously measure all fuses for continuity and replace those that failed.
If it keeps getting stuck on the white screen, I guess the DSP is gone.

[kchung]

So IC732 based off of the service manual?

Is it possible to replace that or better to just get a new PS1? From my research it seems like the 7501 is one of the better models to work with so I guess I'm just disappointed I screwed up so bad.

[rama3]

It could be any part that has to pass an initialization check before the BIOS resumes.
The DSP assumption is just from prior experience.

You still need to check all fuses before making assumptions

[kchung]

So I turned on the PS1 with nothing connected but power and the AV cable. No CD drive or controller ports.... AND IT TURNED ON AND BOOTED?????

So I tried to do it again and this time it's back to being stuck at the white logo screen?

Just did a continuity check and all fuses seem fine. I'm going to check voltage in a moment and compare to the values mentioned here: https://assemblergames.com/threads/test ... ard.55739/

EDIT: Looks like the voltages are fine... Very odd that apparently the PS1 will boot occasionally?

EDIT: Also checked Q609 and it appears to be reading at about 4.2-4.9V on the side with two leads and 3.53V on the side with one lead. I assume this is fine. I'm not a great electrical engineer.

[kchung]

So I spent some time on this with a friend and after a blowing a bunch of stuff off the board and adjusting the pot it boots properly and CDs will sometimes read.

So all in all, checked the fuses and blow off all the junk that might've gotten on your board.