a/v out help... newbie with meter

Discussion in 'General Electronics Chat' started by s_mack, Dec 17, 2011.

  1. s_mack

    Thread Starter Member

    Dec 17, 2011
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    Hi. I googled for days... eventually I thought it might be best to find an electronics forum like this and just ask for help.

    I bought a baby monitor a few months ago with one of the features being an a/v output to a tv. Its by Motorola - a big brand for sure, but not one really known for this type of device... and now I know why! They offer no specifications whatsoever and their manual is useless. It states to use "an appropriate" cable to connect the monitor to a TV. Their website is no help - it doesn't even acknowledge they make the product - and nobody at their call center seems to know what I'm talking about. From Google, all I can find is other people asking the same question.

    On the device is a mini-USB 5-pin port labelled "AV out". My guess is that they used mini-USB for cost reasons and not to conform to any USB standard for data communication because there's no indication whatsoever that this device can be hooked up to a computer. There doesn't seem to be such a thing as a "standard" mini-USB to AV cable on the market. So I'm thinking that one of the pins video and one is audio (and one is ground?) and I should be able to make a cable. I have a multimeter and a soldering station... is there any way I can test what pins are what?

    I have zero experience in a/v beyond listening/watching it! :)

    Thanks.

    - Steven
     
  2. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    PLease post a picture of the PCB area containing the "USB" port, both sides if possible or better showing the whole PCB. If there is a video signal it should be possible to find out where, however it would be best to have an oscilloscope for that...

    Also post the model # of the "Motorola" babyfone. Possibly it is not even made by Motorola. You can buy "iPhone" and "Sony" Walkmans from Asia which have nothing to do with these manufacturers. Beware of the clones :)
     
  3. Kermit2

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    Feb 5, 2010
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    Some equipment uses USB for a power supply also. does this monitor have a separate power supply input or plug?
     
  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    It's probably a charger that charges it.

    No RCA jacks or mini HDMI connector?

    Some USB cables, like those for some phones, also provide the audio out, and theres a USB-Headphone adapter you get from motorola (or it was taped to the box you threw away)
     
  5. praondevou

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  6. thatoneguy

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    Yeah, if that is a mini USB of the correct type, there are 6 types, mini and micro and 2 of each, 4 and 5 pin as well.
     
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Yes...Apparently there are a lot of different cables USB-AV outthere.

    if it's really a common video signal then it's doable, though. With the right equipment , pictures from PCB and some patience...:)
     
  8. s_mack

    Thread Starter Member

    Dec 17, 2011
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    Thanks for the replies everyone!

    The model is MBP36 (same as MBP33 but with pan/tilt and a larger screen). I'm sure it is a Motorola product - at least branded. You can find "baby monitors" on the Motorola website, but retardedly they show a picture of this model with a link to some audio-only model. Anyway, there's no getting any help from them at all.

    I don't have an oscilloscope and I wouldn't know how to use it if I did! (but I am willing to learn - any tips on getting a cheap one that works?)

    Here are the best pictures I could take. I struggled to get the shell apart and ended up breaking half the clips in the process - only to find the speaker wire and antenna get in the way of really seperating the two halves, so I couldn't get very good pictures of the main component side.

    As far as I can tell from the manual, the USB is not intended for anything other than AV out. It is marked "AV out" and the only reference to it in the manual states it is for output to the TV. Yes, it has a separate power supply ac jack (and also runs on battery).

    I don't believe it is a charge but it may be. I'm not going to try it :) No, there's no RCA jacks or HDMI - just the "usb" jack clearly labeled "AV Out"

    I ordered a cable like that (Kodak U8) and when it arrived it was not a mini-USB. I'm not sure what it was - probably proprietary to Kodak? It had too many pins and physically slightly different. In the description on that link you posted, you'll find this for specifications:
    and the jack in my unit is a 5-pin mini-USB.
     
  9. thatoneguy

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    Feb 19, 2009
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    Post one photo facing the jack, as close as you can so we can see if it is a "Standard" type.
     
  10. R!f@@

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    Apr 2, 2009
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    Do not plug in anything other than what is recommended.

    And do not plug it into a computer....u might damage the USB port of ur PC.

    I need better picture of it...good close ups..

    Got to see those traces .............
     
  11. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    As thatoneguy said, first thing is to determine if it's really a USB like receptacle.
    Does it look similar to the mini or micro receptacles here:?
    [​IMG][​IMG][​IMG]

    Does a common mini USB plug fit in there?

    Then:
    All 5 pins seem to be in use. Would be nice to find out a reference (Gnd). Is any of the pins connected to the big copper areas on the PCB?

    [​IMG]
     
  12. crutschow

    Expert

    Mar 14, 2008
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    I Googled "mini 5-pin usb to RCA AV cable" and got several hits. Here's one, for example.
     
  13. s_mack

    Thread Starter Member

    Dec 17, 2011
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    Yes, it is absolutely a mini USB connector. Exact same as the dozen other small devices I have (GPS, camera x 3, camcorder, mp3, harmony remote, etc etc etc) and yes the standard cables that come with those devices fit perfectly in the port.

    In the attachements, I included thumbnails but also a zipped file of higher quality copies. I'm hesitant to take it apart again, considering I've now damaged the case - if any more clips go then I'll probably have to glue it permanently.

    Carl - thanks for the link, but that says its for Sony. If there's any company that refuses to conform to any sort of standard, its Sony. Considering there is no "USB to A/V" standard, what are the odds that it will work? What are the odds it will damage it? That's why I'd like to take measurements of the pins (but how?) to try to figure out what is what first.

    I am certain I can discover which pin is ground, by simply using the meter to test each pin for continuity against the battery negative terminal, correct?

    - Steven
     
  14. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Possibly, or by measuring continuity between the pins and the ground plane. See my previous post.

    When you find the ground pin then measure between ground and the other pins to see if you find any DC voltage, just to make sure that you don't connect it to the TV.

    I never managed to burn a video input of a TV when inverting video/audio etc. I'm not sure how they are coupled inside the TV though.

    I guess it would be easier to find the audio signal(s) first.
    If you have found the ground then couple the other pins (unless it's a pure DC for some reason) via a capacitor to the audio input of a radio or something similar.
     
  15. s_mack

    Thread Starter Member

    Dec 17, 2011
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    I did see your previous post - that's why I asked that question. Doing it via the ground plane would necessitate opening it up again :) So I thought the battery -ve terminal would be easier.

    Does the value or type of capacitor matter? What's the cap do in that case?
     
  16. praondevou

    AAC Fanatic!

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    Yes, that is if the battery - terminal is connected to GND. Try it.

    The capacitor provides isolation for DC between the monitor and the radio/amplifier.

    The best way would be an oscilloscope but they are not cheap and it's not worth to buy one just for this job.
     
  17. JimJ

    New Member

    Dec 19, 2011
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    I'm also looking for an answer on this topic.

    These two baby monitors (MBP33, MBP36) both have this AV out jack. Both are made by Binatone (a UK company) and marketed by Motorola.

    I've posted this same question on the Binatone site over two weeks ago, and nobody can help me. Same situation with Motorola baby monitor customer support, where I've spoken with them and also emailed.

    The only standard USB to video connection I'm aware of is MHL (Mobile High Definition Link), but that involves a micro USB, not a mini USB jack as in this situation.

    If somebody can get this to work with a custom-built cable, there just may be a market for making and selling such cables.
     
  18. s_mack

    Thread Starter Member

    Dec 17, 2011
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    The problem (of course lol) is that those that need this item, don't have the time to investigate it, because we have babies that need our constant attention! And the only time they aren't in need of our every moment... they are sleeping, and then we need the monitor to not be in pieces! :)

    But I'll attempt to figure this out.

    - Steven
     
  19. R!f@@

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    Apr 2, 2009
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    We could solve this quite easily if you can give us closeups of that mini USB jack from both sides.
    We need to see where the traces leads to.
     
  20. s_mack

    Thread Starter Member

    Dec 17, 2011
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    I thought I did that... did you see the zip file containing the pictures? They're as close up as my camera can get. If you need closer... then I can do that after Christmas when my wife opens her gift :)
     
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