SONY - DVP S300_DVP S500D_DVP C600D_DVP S7700 _ Service Help _Power Supply

NO RESPONSE TO THE POWER ON BUTTON

There are three common causes for this problem.

• A damaged power supply;
• A short on another board that causes no power supply output voltage; or
• A defective front panel encoder  preventing IC604 from reading the power ON button by locking up its program so the unit may not turn ON (intermittent turn ON).

REPAIR

The power supply runs all the time when 120VAC is input, producing E +5V. The +3.3V, +5V and +12V outputs are switched ON when the unit is turned ON. You first need to determine if the basic power supply is defective.

• Unplug the cable from the only connector on the power supply, CN201.  Look for E+5Vdc at CN201/pin 6 (alternate test point is at PS312) from the power supply board. If there is no voltage, the power supply is inoperative. The most common cause is a shorted main oscillator MOSFET transistor, Q103, which has taken out the main fuse. Q103 P/N = 9-880-437-01 which is a 2SK2798 for the USA models.  If the new Q103 fails or there is still no output voltage, replace the associated control parts Q101, Q102 and D104.
• If the power supply does produce the E+5, the front panel rotary encoder or a short in another board is suspected. The encoder is attached to a ribbon cable that plugs into CN103 of the front panel board.  Unplug the encoder, plug in the power supply cable and press the power ON button to verify the defect.
• If the unit still did not power up, you may leave the rotary encoder cable detached while you look for the short circuit that is preventing your unit from responding to the Power ON button. This is because the front panel must be removed to reseat the encoder cable and it is more important that you locate the problem. Either use your ohm meter to locate a short at the power supply connector CN201 or repeatedly press the power button while monitoring the output voltages to see which one is missing:

CN201/pin 1 = +5.2Vdc

CN201/pin 2 = +5.2Vdc

CN201/pin 3 = Ground

CN201/pin 4 = +3.3Vdc

CN201/pin 5 = Ground

CN201/pin 6 = E5.Vdc

CN201/pin 7 = Ground

CN201/pin 8 = P Cont (input)

CN201/pin 9 = AU +12Vdc

CN201/pin 10 = AU Ground

CN201/pin 11 = AU –12Vdc

CN201/pin 12 = -12Vdc

CN201/pin 13 = Ground

CN201/pin 14 = Motor +12Vdc

CN201/pin 12 = Motor Ground.