Amek Angela - LED meter problem

Discussion in 'Tech Talk - Electronic Repair Modifications DIY' started by Asaf Smilan, Feb 21, 2018.

  1. Asaf Smilan

    Asaf Smilan Active Member

    Joined:
    Feb 21, 2018
    Location:
    Tel-Aviv, Israel
    Hi,
    The LED meters on my AmekAngela have this problem that it takes about a minute for the LEDs to shout down after the music stops,you can see it in this video:

    What could causing this problem?
     
  2. DonnyThompson

    DonnyThompson Distinguished Member

    Joined:
    Nov 25, 2012
    Location:
    Akron/Cleveland, OH
    Home Page:
    Hmmmm....
    Before I watched your video my suspicion was that maybe you had inadvertently set the meter ballistics to "slow"...
    But after seeing what's going on, man...I don't know, and I'm not all that familiar with Amek desks...
    @Boswell ? @Kurt Foster ?
    And didn't we have an RO Member who was rebuilding an Amek console a few years back? Was it Joel?
    @Asaf Smilan ...
    Is this happening every time you stop signal? Or is it intermittent?
    Has this been happening for a while, or did it just start?
    Are you noticing any other issues... Noise? Hum? Any sudden increase or decrease in signal?
    Assuming you've made no recent mods or other repairs to the desk...
    Just thinking out loud....
     
  3. pcrecord

    pcrecord Quality recording seeker ! Distinguished Member

    Joined:
    Feb 21, 2013
    Location:
    Quebec, Canada
    Home Page:
    Seems like an internal power problem. Some capacitors may need to be changed..
     
    Kurt Foster likes this.
  4. paulears

    paulears Well-Known Member

    Joined:
    Feb 7, 2014
    Location:
    Lowestoft - UK
    Home Page:
    Double check the phantom power is working properly, problems with the two matched resistors can mean there is a DC imbalance and the input meters are seeing voltage, which eventually discharges via the capacitor and the meters return to normal. Unlikely to come and go, but if there is a switch to turn it off try it. Had this on a soundtracks desk in the 90's. You can get the same effect when you connect a sub mixer that has phantom accidentally turned on.
     
  5. Boswell

    Boswell Moderator Distinguished Member

    Joined:
    Apr 19, 2006
    Location:
    UK
    Home Page:
    There are several significant observations to make about the behaviour of the metering shown in the video.

    Firstly, all the channels are affected, so that, for example, it's unlikely to be a phantom power problem on any one channel.

    Secondly, the fault gives similar, but not the same, magnitude of effect on every channel, and corresponding decay times.

    Thirdly, there are not many places in a complex analogue system such as the Amek Angela that have time constants of order 1 minute.

    The initial suspect area is the power supply rails, as Paul suggested. I've not been able to find any Angela schematics on line, so a guess would be that the design of the metering section is not proofed against variations in the internal power rail voltages.

    A cause of the problem could be leaky reservoir capacitors, or high-impedance contacts at the rectifier diodes or at the voltage regulators. If I were sitting next to the console with its lid removed, I would put a digital voltmeter on the power rails feeding the metering board and see how much variation in rail voltage could be invoked by feeding a signal generator or some loud music through many channels at once.
     
    DonnyThompson likes this.
  6. paulears

    paulears Well-Known Member

    Joined:
    Feb 7, 2014
    Location:
    Lowestoft - UK
    Home Page:
    If you accidentally apply power to a Soundcraft mixer (the one I was using was a Live 8-32) input - I had it's output plugged into channels 1 and 2 of a Yamaha, with phantom turned on accidentally - and all the Soundcraft meters, including the groups all lit up to the same level. sticking power up the output of a mixer I can imagine causing problems in the output section, but it managed to get to every channel. The cause of this fault will be a strange one. The trouble with phantom power is that any fault will be applied to one point on the desk, but once it's there, it can spread because all the channels share so much - the axes and groups, PFL lines and stuff like that. A fault in the master section could leak back through the grouping on old style desks. I had an old Mackie desk years ago that when you turned the power supply on - every meter kicked and fell gently back. Much defy common sense.
     
  • AT5047

    The New AT5047 Premier Studio Microphone Purity Transformed

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice