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Control of Beovision 7-40 floor stand

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achangtrakul
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achangtrakul posted on Wed, Sep 23 2015 9:31 AM

Time has come to retire my Beovision 7-40 (MK II). I am going for a none B&O flatscreen, that I was thinking of mounting on the B&O floor stand, keeping the Beolab 7-2 as a sound bar for the new TV. I would like to be able to continue to control the motor in the stand with the BEO4 remote. Anybody here with previous experience or suggestions with this proposed set-up?

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drmichi
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According to the service manual, there is the following pin assigment:

  1. Pin1: GND
  2. Pin2: Turn left
  3. Pin3: Turn right
  4. Pin4: (?) current position?
  5. Pin5: +14V

Does anyone know which pin is which one on connector?

BEOVOX141
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The 7-40 has both pan and tilt in the same connector. The schematic above is properly from a BV7-32?

In order to properly answer the question, I need to know the following, would you consider choosing the TV based on the ability to operate the stand?

Would you accept the BEO4 as a SEPERATE remote for the stand. And are you in the US? if so you might have a better chance.

drmichi
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I have the motorised floor stand of the old BV7-40 MKII, and a 55" Samsung LCD TV.

  • The Samsung TV will be attached through a self made adapter plate
  • The BeoLab 7-4 will be connected through the "TV Digital Optical Out -> Analog Stereo Converter -> PowerLink Adapter Cable"
.

I would like to control the floor stand from a NodeMCU V3 micro-controller, which is attached to the USB port of the TV and a separate power supply.

  • When TV is starting up, the NodeMCU detects USB power and moves the floor stand in the defined position
  • When TV is turned off, the NodeMCU detects that USB power is lost and moves to the zero position
  • Optionally, through an IR receiver I could also be possible to manually control the floor stand through a remote (e.g. Beo4)

 

BEOVOX141
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drmichi:

I would like to control the floor stand from a NodeMCU V3 micro-controller, which is attached to the USB port of the TV and a separate power supply.

  • When TV is starting up, the NodeMCU detects USB power and moves the floor stand in the defined position
  • When TV is turned off, the NodeMCU detects that USB power is lost and moves to the zero position
  • Optionally, through an IR receiver I could also be possible to manually control the floor stand through a remote (e.g. Beo4)

Great simplistic approach! Perhaps this can a bit of help. I believe the control signals are 5V, but they might work with the 3V3 Node I/O. Note they are active low. The feedback can be read by the ADC. I would guess it's centered around 5V but i really don't know! Check the signal before attaching it to the node, you might need to scale and perhaps offset it! This schematic is not that clear but W50 is the cable hanging loose in your picture. I have always wondered exactly how the two active low signals can do FOUR different thing, left, right, up, down. Perhaps you will find out?

Bottom line the BV7-40/55 stand is significantly more complicated than the BV7-32.

EDIT: If you scrap the TV anyway make sure to scavenge the IR receiver board it could come in real handy for your project!

TWG
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TWG replied on Thu, Aug 15 2019 6:07 AM

Keep going with that project please!

This motor stand solution via Lintronic might be helpful, too:

http://lintronic.dk/AppNote_PulsingOutput.pdf

BEOVOX141
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TWG:
Keep going with that project please!

We are all over it! ,- but wait! The most important part is missing Confused The ir Receiver! What are we going to do, if only there was some easy way....

drmichi
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Mechanically it's done, except the cable routing.

Next task is to attach an Oscilloscope and analyze how to control tilt / rotate with that 5 plug wire.
Since the BV7-40 still works, I think I will be able to find a pattern how to control the stand through a NodeMCU. 

To get the BeoLab 7-4 working, I plan to use the "Stereo MiniJack with USB Trigger cable".
https://www.av-connection.de/?PGr=6497

riverstyx
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Suggested by drmichi

This extract from the service manual should help with control of the stand - you'll still need to scope the position feedback signal to see how that is encoded though.

The manual says: "Pin 4 Stand Position Feedback 0 - 5 V pulses" but doesn't go into any more detail.

BEOVOX141
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Looking forward to seeing what you find, 2 bits only, Pan Tilt both using the same feedback. it has to be somewhat complicated.

Even more complicated by the fact that the pulses will properly only show, when its detected by the BV, which means you have to cut into the cable, I am not really inclined to do that,- yet

One more thing to look for, the stand is only detected after a power cycle, perhaps some initializing is taking place. 

If you make this part work Ican properly handle the IR part.

drmichi
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Thanks for that! I see they modulate 4 signals on two wires with a voltage level.
Lower voltages at 2.5V control the tilt, higher voltages at 5V control the rotation.

Should not be a problem, just requires some voltage drivers after the GPIO outputs.

BEOVOX141
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Brilliant!

Good engineering, they already properly exhausted the 5V logic bits on the BV7-32,stand and when the 7-40 came along they simply worked below the threshold for the tilt function effectively having 3 states in one bit! Which properly means the control for all the bases of the different stands are identical. And since i have a bunch of 7-32 stand available i would actually make sense for me to dismantle one of those, for som reverse engineering.

What about the feedback,- modulated as well ?

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