mcth 28V LPS and SMPS technical measurements

Discussion in 'Headphone Amplifier Measurements' started by atomicbob, Apr 8, 2018.

  1. rtaylor76

    rtaylor76 Can't wipe his tag

    Friend
    Joined:
    Nov 9, 2015
    Likes Received:
    522
    Dislikes Received:
    22
    Trophy Points:
    93
    Location:
    Nashville, TN
    It's actually black and you can totally tell if it has been sprayed an by how much. I mean I would not grab it, but I feel safer brushing by.

    The best will always be an inline fuse for safety and from current overdraw to protect the transformer and from your house catching on fire.
     
  2. Sanjeev Jain

    Sanjeev Jain Rando

    Contributor
    Joined:
    Nov 6, 2017
    Likes Received:
    3
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    Bay Area, CA, USA
    @atomicbob ,

    I recently acquired a 3Amp model, A28MT300A to be used with MCTH and being a total electrical novice, could you please help me with the fuse to be used in the inline fuse holder.

    Seems like the Instructions Manual for A28MT300A suggests to use a time-delay UL Listed fuse (250V) in the AC input wiring. So based on the 3 Amp output, would something like (3 Amp Time Delay Glass Tube Fuse 250Vac, UL Listed ) linked below work?
    https://www.amazon.com/Bussmann-BP-MDL-3-250Vac-Listed/dp/B000VWE90O

    Please let me know.
     
    Last edited: May 6, 2018
  3. rtaylor76

    rtaylor76 Can't wipe his tag

    Friend
    Joined:
    Nov 9, 2015
    Likes Received:
    522
    Dislikes Received:
    22
    Trophy Points:
    93
    Location:
    Nashville, TN
    I think all you need is a 2A fuse.

    For Acopian only, fuse size in amps = (Output Voltage * Output Current * 2.93) / 115 VAC.

    I don't know why this hasn't been shared already on this thread, but there it is.
     
  4. Sanjeev Jain

    Sanjeev Jain Rando

    Contributor
    Joined:
    Nov 6, 2017
    Likes Received:
    3
    Dislikes Received:
    0
    Trophy Points:
    3
    Location:
    Bay Area, CA, USA
    Thanks rtaylor.
     
    rtaylor76 likes this.
  5. rtaylor76

    rtaylor76 Can't wipe his tag

    Friend
    Joined:
    Nov 9, 2015
    Likes Received:
    522
    Dislikes Received:
    22
    Trophy Points:
    93
    Location:
    Nashville, TN
    So my Acopian A28MT300A has decided to start making a slight bit of noise. Not electronic noise, but physical noise.

    It is kind of like transmitter hum, but every now and again, it will get slightly louder and higher pitched. It is kind of random, but also pulsing about once every 4-6 seconds. I think the cage is kind of loose and just amplifiying the vibrations coming from the transformer. I know the cage for mine came slightly dented and I tried to use a small screwdriver to put in there to pop it back out, but it did not stay.

    Anyway, it is not as loud as my hard drive, but enough for me to notice. Also it sits about 4 foot away to my right and it is right at ear level. Just letting others know if they have the same or similar model. Results may vary.

    It kind of makes me want to add a power switch to the LPS. I don't leave my MCTH on all the time as I don't like leaving tube gear on all the time. SS gear I have no issues, but that LPS is constantly putting out 28V no matter what. I know it is only drawing the small amount of mA that the linear circuit needs, but still.
     

Share This Page