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RE: If the photo is on your computer, the go to the new message box and look down

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john635@earthlink.net

In Reply to: RE: If the photo is on your computer, the go to the new message box and look down posted by alaskahiatt on October 23, 2024 at 12:20:26

Good morning everyone!
Ok, here goes nothing.
I'm phrasing it this way because, I have no eye sight above lights and shadows.
Everything I do via any digital device, all has to be done threw text to speech converters.
On my computer, I use JAWS.
On both my iPhone and iPad, I use Voiceover.
I had to take the amp outside in the yard.
This is so that, I could use the sunlight in order to be able to shoot the inside of the amp.
I had to email the picture from my iPhone, to my computer.
If only I could use a USB cable to cut and paste pictures from my iPhone to my computer.
My wife, can do a lot of things with the mouse.
But sense I can't see well enough to do that with the mouse, the keyboard of my computer happens to be my best friend when it comes to this kind of a thing.
So, please be patient with me.
I will give it a go.

Follow Ups:

RE: that's a good photo - Palustris 14:32:46 10/24/24 (3)
OK, that's a good photo, but not large enough for real troubleshooting.

I can see that the amp is grounded at the speaker outlets and there is one ground wire that goes into the amp probably to the cap at the top left. From there it goes to more caps and at that point it is lost. I can't see the AC power inlet and if the unit is grounded through the power cord as it should be. I can't see where the audio input is grounded or the input tubes where there cathodes are grounded. There is just not enough information; but there is the appearance of multiple ground loops.

So, at this point I would reconnect anything you have disconnected and find a technician or audio hobbyist in your area to help with the diagnosis.
- RE: that's a good photo - john635@earthlink.net 14:51:18 10/24/24 (2)
  Good afternoon Palustris!
  The only wire that I disconnected, was an earth ground wire that was attached to one of the output transformers, via a bolt and nut.
  The wire is turminated by an O-lug.
  And that wire is coming in from the IAC power inlet.
  But on the primary side of the output transformers, they each have two wires.
  One is going to the plate of each one of the output tubes, and the other wires are going to the B-plus power supply.
  I mean B-plus voltage.
  But on the secondary of the output transformers, there are three wires each.
  One is ground, the other two are 4ohms, and 8ohms per channel.
  But wouldn't that choke get rid of hum too?
  I have a much larger amp then this one, that also has a choke in it too.
  it is equally the same age as this one.
  But it's push-pull.
  Two KT77 tubes per channel in that one.
  And after 16 long years of service, I've never once heard that amp hum.
  But that one, is my Eastern Electric M-520 amp.
  But the one that I uploaded a picture of, is the inside of my Musical Paradise MP-401 amp.
  This is the one that I'm trying to figure out.
  I also read somewhere on the net that, "heavy filtering, can make single ended tube amps stop humming."
  But it didn't say how.
  I guess you have to use more caps?
  - RE: that's a good photo - Palustris 15:06:22 10/24/24 (1)
    The problem is not the wire that grounds the amp by the power cord. That should be connected or the amp won't be grounded.
    
    You never answered my question: is anything connected to the amp such as a CD player?
    
    Has this amp ever worked without hum? Is this a new problem? How old is this amp?
    
    The problem is probably not insufficient power supply filtering; there are plenty of capacitors unless the amp is old and the caps have dried out. The problem appears to be a ground loop.
    - RE: that's a good photo - john635@earthlink.net 01:42:48 10/30/24 (0)
      Good morning Palustris!
      I don't know if you saw my last few posts, but I did tell Cougar about all of this.
      But sense you asked, no.
      The amp hummed, as soon as I unboxed it, and hooked it up.
      The amp was made in 2008.
      So there for, this amp is 16 years old.
      I drove the amp via my iPad, and Earman Angel portable headphone amp/DAC.
      I wanted to see what this amp sounded like, when fed DSD files.
      Aside from that, my Presonus Quantom ES 4 audio interface, with the computer providing the digital audio signal.
      And later on, my digital talking book player, with NLS cartrages that have 16bit, 44.1KHZ wave files.
      But either way, I couldn't make the humming noise go away.
      I did call and spoke to mark about it yesterday afternoon.
      When I told him about the part where and when I removed the tubes, and still heard the humming noise, it stumpped him.
      But I told him about that problem, sense he was the one that sold it to me.
      I think he's gonna make arangements for me to send it back to him, so that, he can check it out.
      But I also thought about something.
      If the primary side of the output transformers are wired up wrong, wouldn't that be causing the humming noise problem too?
      Thanks in advance!
      https://www.soundsclassic.com (Open in New Window)

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