Disc spins twice - no boot (PU-23 board)

[donfuego]

While tuning the laser I might accidentally have shorted some of the pins on the north side of the CN702 connector.

Now it won't load any discs.

- PSX starts up and goes to "Main Menu" screen
- When closing the CD door the cd spins very slowly twice
- The laser is trying to focus (moves up and down)
- Laser diode seems to work but is weak
- Unit doesn't detect any disc has been inserted - just stays at main menu screen

Observations:

Video 1. https://www.dropbox.com/s/dseu9ld40uds8 ... 1.mp4?dl=0
Video 2. https://www.dropbox.com/s/mnkyiwnyq8feo ... 1.mp4?dl=0


Laser voltage (measured at trim pot on laser assembly) now at 6 mV. Used to be at 12 mV.

Voltages at CN702:

Code: Select all

PIN	IDLE STATE			DOOR CLOSED

1	floating (160 mV)		2.29 V (momentary)
2	3.48 V				same
3	1.74 V				same
4	1.75 V				same
5	1.73 V				same
6	1.72 V				same
7	1.72 V				same	
8	1.75 V				same
9	0 V				0.75 mV (momentary)
10	0				6.2 mV
11	0 V				0.6 mV
12	8.5 mV				83 mV (momentary)
13	3.93 V				3.5 V (momentary)
14	3.92 V				same
15	3.94 V				3.76 V (momentary)
16	3.92 V				7 V (momentary)

Don't have any experience with PSX so don't know where to go from here...

Edit: Looking at the schematics the voltage readings seem reasonable. I wonder if Q701 or its surrounding components could be the problem. Don't know how to test it though.

[~PSXLoVeR95~]

Hello. Maybe you broke the RF Amplifier (on the SCPH-9002 should be the CXA2575N aka A2575N). LDON (APC ON) is present (watch the laser radiation). Did you have a broken PSone? They have the same RF Amplifier. Try to replace that IC.

Oh btw, did you test another laser?

About Q701. That regulator is used for control the laser diode. If was broken/burn, you shouldn't see the laser light.

Check this out: