Thread: BMMCC 14.8V Battery Module by RADIOPROEKTOR

Results 1 to 10 of 94

Threaded View

Previous Post Previous Post   Next Post Next Post
  1. #11  
    Senior Member shijan's Avatar
    Join Date
    Apr 2012
    Location
    Odesa, UA
    Posts
    1,145
    Stelvis, all grounds are connected but if you connect monitor to camera, turn them on and measure voltage between monitor DC ground and HDMI cable ground, you will see some very small voltage there (average 0.06V). I have no idea why.
    I found that this voltage leak depends of HDMI cable quality. Branded cables with better isolation leaks 0.01-0.02V. Highly used cheaper OEM China cables leaks 0.06-0.15V. This ground voltage leak exists even if you power camera and monitor from separate batteries.
    If you turn off any device there is no voltage leak between HDMI and DC grounds.

    Not sure if i understand the thing but i have a theory that it may be due both electrostatic damage and due ground loop same time. Without ground loop when you touch the camera, electrostatic voltage splash from your body goes away somewhere to camera body and next somewhere to outer ground. But when there is a ground loop with HDMI/SDI, electrostatic voltage splash may go to electronic circuit and damage HDMI chip. This is explains why those damages are so random. I used single battery setup about the month without any problem and once upon a time i turned camera on and no HDMI signal.
    beside electrostatic voltage splash this also could be a moment when you insert cable into the battery and produce small electric spark and due ground loop it somehow may damage HDMI circuit.

    I don't believe that average measured 0.06V potential between different grounds may somehow actually damage HDMI chip. Ground loop cause hum, noise, interference, but how so low voltage can damage electronic chips?

    Maybe we need to look for some kind of electrostatic protection instead of isolated grounds? But i am not so advanced in electronics so this is just a guesses.

    UPDATE:
    I found that same small voltage leak is present even if you measure between grounds on both HDMI cable ends. (Cable must be connected to the camera and monitor and both devices must be turned on)
    Last edited by shijan; 10-09-2018 at 03:16 PM.
    All my custom made accessories for BMMCC/BMMSC now available here https://lavky.com/radioproektor/
    Reply With Quote  
     

Similar Threads

  1. Replies: 16
    Last Post: 11-11-2019, 11:59 PM
  2. FS: ARRI Type Rosette Mount Module for BMMCC by RADIOPROEKTOR
    By shijan in forum For Sale / Want to Buy
    Replies: 8
    Last Post: 11-11-2019, 11:56 PM
  3. Replies: 3
    Last Post: 11-25-2017, 11:13 PM
  4. Replies: 12
    Last Post: 11-05-2017, 02:13 PM
  5. Replies: 20
    Last Post: 10-20-2017, 09:29 PM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •