Disc spins twice - no boot (PU-23 board)
Posted: April 15th, 2022, 2:12 am
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:
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.
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)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.
