Philips DVP520 Service Manual page 13

Disc cannot be read .
Disc cannot be read.
Yes
Check the FFC connection
between 24P and the loader.
Yes
Check whether there is laser
voltage (2V for VCD and 2.2V for
DVD) on Collector of Q5 &Q6
Yes
Check whether U1, U2, U4
and peripheral components
are eroded or badly soldered.
Yes
Check whether there is RFO signal
on pin17 of CN2. (The normal RFO
signal is a clear reticulated wave)
Yes
Check the connection
between U4 and U1
Yes
Replace U1 or loader.
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No
No
No
No
No
4-4
Check the loaded circuit
1.Check voltage on pin 52 of U1 varies
between 0 and 3.3V:
3.3V for VCD
0V for DVD
2.Check whether peripheral components
are eroded or defect
Re-solder or replace the defective parts
Check U1 and peripheral components
Fix connection
Trouble shooting chart