I have a pioneer DV-490 V-s DVD player . when I push the tray open button the tray opens then closes immediately. This is done when you press the button on the machine and also when you use the remote control. What can be done to solve the problem knowing that I have a good idea about electronics.

SOURCE: Locked dvd tray.

Press and Hold EJECT Button, While UNLOCK Is Displayed :-)

SOURCE: dv-343

open the case take the metal piece with disc spinner of {one screw}then pull drawer out then push drawer back in and assemble the unit plug power back in and try again

SOURCE: DVD PLAYER DISC TRAY DOES NOT OPEN

tap it gently from the side while pressing the button......or with a knife try to open it gently...while pressing the button....after it,s open..clean the side n the belt..

SOURCE: LG RHT 398H. DVD tray not closing.

I've dismounted the unit and it seems that I have located the problem. The tray is connected to a wheel, so any displacement is translated into a rotation of this wheel. When the tray is near the close position, it releases a mechanism in order to position the lens. Summarising: if you have pushed the tray with your hand instead of pushing the button open/close, probably you have introduced a desynchonization. To solve this, when the tray is in close position, apply a small rotation to the wheel in order to compensate the desynchronization. There is not an exact position, but you need to try. A few degrees is enough. Regards

SOURCE: Pioneer DV-C36 disc tray will not stay open

Solution for Pioneer DV-C36 Multi Disk DVD player - tray door will not stay open.

My player would open the disk tray when the open button was press but when the tray was fully open it would retract
back into the unit leaving no time to change or load disks.
I found a poor connection at the ribbon cable connector was causing this problem. A seven conductor ribbon cable
connects the main unit with the travelling tray. A position switch (S21) senses when the tray is fully extended and retracted.
On my player pin 1 of the ribbon cable connector on the travelling tray was not making an electrical connection which
causes the control system to retract the tray. The fault lies in the connector - the tang was not pressing against the ribbon cable conductor.
I was able to desolder the connector and pull the contact out just far enough to reform the tang with fine needle nose pliers.
This is very tedious and required an eye loupe for magnification.
Tools required:
#1 and #2 phillips screwdrivers
Soldering and desoldering irons (or other desoldering tools)
Fine needle nose pliers.

Remove the tray ribbon cable
1. Remove the cabinet cover - 6 screws. Open the tray. To keep the tray from retracting pull the power cord when the tray is extended.
2. Remove the front bezel from the tray. Gently pry up the bezel by relesing the catches with a small screwdriver. Allow the tray to retract.
3. Remove the front panel - undo large ribbon and wire connections on right, remove screws left and right, release
two catch tangs on bottom edge using a small screwdriver on the inside of the unit.
4. Remove the white plastic cover over the laser mechanism ( 2 screws) Remove the disk carrier by removing the center screw.
5. Extend the tray again. When the tray is out the small ribbon cable is visible below the tray. Undo the ribon cable where it attaches to the main unit unit.
6. To slide the tray off the main unit use a small screwdriver to depress the stop catches (2) in the tray. They are molded into the tray.
Pull the tray out further then lift up.
7. Flip over the tray and find the small circuit board the ribbon cable goes to. Desolder the motor wires (red and black) and remove the 2 screws
holding the circuit board and position switch.

Use a multimeter to confirm there is an open or poor connection in the ribbon cable connector.

Remove the ribon cable and inspect the connector with an eye loupe or other magnification device. On my player contact #1 was not positioned properly
to press against the ribbon cable conductor. You can either replace the connector or repair it.
Warning: repairing the connector may damage it.
To repair the contact desolder the connector from the circuit board. Bend the circuit board prong straight and push it into the body of the
connector which will extend the contact out and the contact can be reformed. Be very gentle. Bending the contact may cause it to break.

Reassembly is the reverse. Don't forget to solder the motor wires with the proper polarity. Red and Black are labeled on the circuit board.