Testing fuses on a SCPH-1001 Playstation motherboard

I have an SCPH-1001 model Playstation I got off eBay. The console powers on and boots up, but the drive/laser assembly does absolutely nothing. The disc doesn't spin and the laser never moves. I was told that this can be caused by a bad fuse. The console works fine otherwise. How would I test the fuses with a multimeter? I am very new to all this. Please be as detailed and specific as possible and tell me exactly what I need to do. I have taken the console apart and I believe I know where the fuses are. I just need to know how to test the fuses. Any help would be greatly appreciated.

 

The easiest test is to measure the voltages on both ends of the fuse with respect to ground when the unit is turned on. If the fuses are OK, you should get the same voltage (say 7V or 3.5V) on both ends of the fuse - if you get low voltages on both ends, then suspect the power supply. If you get the normal voltage on one end, but low or no volts on the other then the fuse is blown.

 

Could you tell me what to set the multimeter, as well as anything else I need to know? As I said before, I am very new to this.

 

DC 20V is ideal to set it to, put the black probe on the Ground (usually on the outer edges of the board) then the red probe like Trimesh explained.

 

DC V - something like the 20V range. Connect the -ve meter probe to any of the ground points on the board and then connect the positive to each of the fuses.

I just checked on the board I have here (PU-8, 1-658-467-23 in a SCPH-1001), and the voltages were as follows:

PS601: 7.7V
PS602: 7.7V
PS603: 7.7V
PS604: 3.5V
PS605: 3.5V

I think it's either PS601 or PS602 that runs the CD transport.

 

I wouldn't think the PS1 would need a fuse for the CD drive. I assume it might be capacitors? I'm saying this because when I tried getting the cover thing covering the main components off of the motherboard using a screw driver of a 5501, it accidentally knocked some caps off to the point where the cd drive was non-functioning. Seeing this and my lack of solder skills, it got thrown away along with a Sanyo laser equipped PS2 (which are unreliable little bastards).

 

No, it does actually make a lot of sense having that fuse there - it's connected in the supply to the BTL driver chip (the chip that runs the focus/tracking actuators and the spindle/sled motors) - and due to their internal structure they have a tendency to fail in a way that makes them take a lot of current. On some of the early CD players this resulted in the chip burning a hole in the PCB, which is clearly pretty undesirable from a fire safety point of view.

I've seen quite a few machines with that fuse blown - although normally it's because either the BTL driver chip is blown, the spindle motor is bad or both.

 

I see. So its connected to the ROHM motor driver? Interesting...

 

Well I finally got around to testing the fuses and they all seemed to be fine. I did notice a smell coming from the power supply while testing the fuses. Is that normal? If it's not the fuses what else could it be?

 

It's possible that the Rohm chip we were talking about above is blown up. Have you got a spare optical pickup assembly you can try in the console?