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Intermittent loss of video signal -96' Drum Twist

4 years 1 month ago - 4 years 1 month ago #2709 by Mr Oladimeji Olaoluwa Oyetuga
Mr Oladimeji Olaoluwa Oyetuga created the topic: Intermittent loss of video signal -96' Drum Twist
Hello All,

I recently installed a 96" Drum twister in my plant with a rotating Cradle. The cradle drive controls the rotation of the caterpillar and the cradle as they are mechanically linked via a line shaft.
A video camera is mounted on the cradle to provide a stationary view of the reel winding to the operator monitor. All electrical control signals are brought out of the cradle through a wireless Ethernet link. Power for the reel and transverse motors as well as control power are routed through slip rings.

Problem - I have noticed that the screen is often going off and on intermittently both while rotating and when stationary.

What I have done so far:

1. Since the 12v that power the transmitter comes from slip rings, I have checked the contact and tension on the brush, cleaned out the brushes as well as the slip rings.
2. I noticed a voltage drop every time I connected the transmitter to power (It dropped from 12 V DC to 10.5 V DC) so I replaced the video transmitter(PX915- 900MHz).
3. I tried to relocate the transmitter away from the transverse arm of the cradle to a location where its will not go below the concrete floor while rotating.
4. I have checked the receiver as it relate to the Tens & Ones setting and also changed the antennas.

Despite all these my signal is still fluctuating, please advise.


Last Edit: 4 years 1 month ago by Peter J Stewart-Hay.

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4 years 1 month ago - 4 years 1 month ago #2710 by Peter J Stewart-Hay
Peter J Stewart-Hay replied the topic: Re: Intermittent loss of video signal -96' Drum Twist
Just so you know, I really detest these low voltage supply systems (12 V DC) brought into large rotating industrial machines by slip rings. The power for the low voltage system should come in at line voltage and then be transformed and rectified near the transmitter. The camera, transmitter and LV power supply should be close to the center of rotation of the cradle so that centrifugal forces are minimized.

There are also many other reasons why intermittent transmitter failures occur. Lose circuit boards, cold solder joints on circuit boards and so on.

PS- After your phone call I suggest the following. You must have a qualified electrician present when you do this. Safety is the most important thing. Drum twisters can easily kill or maim people..
- Disconnect the power from the machine and remove the brushes supplying the DC power to the camera.
- Run temporary wires from the power supply to camera.
- Turn the power back on BUT DO NOT ROTATE THE DRUM TWISTER.
- See if the camera is now working. If so, you know your problem is in the equipment you jumped. (Slip rings, brushes,wires to the camera.) If not then you know the problem is in the power supply or in the camera itself.
- Remove the jumper wires and reconnect the brushes, thereby restoring the drum twister to its previous state.

Peter J. Stewart-Hay Principal
Stewart-Hay Associates
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Last Edit: 4 years 1 month ago by Peter J Stewart-Hay.

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