Media bed

Discussion in 'Electricians' Talk' started by moss lea, May 17, 2019.

  1. moss lea

    moss lea Member

    Anyone had problems with lift on a TV media bed? Mine is stuck in the up position and won't budge.
    There is some sort of power as I can hear a slight him when it is on IMG_20190517_103555412-3024x2268.jpg IMG_20190517_164742193-2016x1512.jpg any ideas?
     
  2. MGW

    MGW Well-Known Member

    That looks like a wagon windscreen wiper motor.
     
  3. moss lea

    moss lea Member

    Ha ha. I just looked it up and it seems to be a wagon Bosch wiper motor. How bizarre! So my bed thinks it a car. Now how to fix the ruddy thing.
     
  4. peter palmer

    peter palmer Well-Known Member

    Maybe one of the limit switches is broken, needs taking to bits to what works and what doesn't. It looks simple enough, motor turns a gearbox which winds itself up and down that linear gear with probably a switch at the top and bottom to stop it. I assume its powered from 24V DC then if its a truck motor, there will be a transformer and rectifier pack powering it as well.
     
  5. moss lea

    moss lea Member

    I was trying to work out the process and I concluded that something is stopping it from moving. It is completely stuck, no budging. I thought it might be some sort of switch. Under the motor there is a small black box with 2 thin wires, red and black. So it could be that. Also the voltage is 220-240v AC so I assume the the power supply, which is humming is also a transformer.
     

    Attached Files:

  6. DIYDave.

    DIYDave. Well-Known Member

    It’s humming as you’ve got power going to motor but as you say, something is jammed

    As the electricity isn’t being used up to turn the motor, you get this buzzing sound (all very non technical description I realise)

    Don’t continue to switch power on for any length of time as possibly burn out motor (unless protected by a fuse)

    Time to strip down and investigate
     
  7. moss lea

    moss lea Member

    And there is the the problem. As the lift is stuck at the top, I can't get to the parts. It seems that bed is sealed and you can only access from bottom. What I need is an override.
     
  8. moss lea

    moss lea Member

    Here's the power supply
     

    Attached Files:

  9. Bob Rathbone

    Bob Rathbone Well-Known Member

    Those relays used to control the motor look very small, I have had problems with these in arcade machines such as cranes, they fail often. OK so how to get the thing to lower, just unplug the motor from the PCB and feed a 12V dc supply to it, one way it will rise and with the polarity reversed it will fall. If it is stiff or jammed it may need 24V and a helping hand. Don't leave it on too long, 5 seconds at most.
     

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