Announcement

Collapse
No announcement yet.

5e3 power transformer?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 5e3 power transformer?

    hey guys, i have a 5e3 amp here on the bench and the guy that owns it says in just stopped working after a gig.
    He thinks it may be the power transformer. i opened up the amp and there are no visible signs of any bad,burnt,blown components. the amp keeps blowing fuses when turned on. i have the power tranny taken out of the amp and it's a weber wo25130 power tranny. i did a ohm check on the following leads and here's what i got.

    Primary- 3.4 ohms
    secondary- two red ht together=16.7ohms, one red with ct =33.4ohms, other red with ct =48.7ohms.
    - two 6.3 heater windings together =.4 ohms. with ct .4ohms each.
    - two yellow =.5 ohms.

    the tranny has two red ht @680v/150ma and two whit/red ht @540v. If it is the the 680v ht that is the problem, can i use the 540v winding instead?

  • #2
    Transformers are usually the last thing I suspect. They rarely fail. Since you already have it out of the amp, I would apply power to the primary via a light bulb limiter or current limiter, if you have one, and measure the secondary to see exactly what it's doing. You could also bring it up slowly on a variac while monitoring current. If it still draws massive current with no load, then it's bad.
    Last edited by The Dude; 05-04-2018, 10:14 PM.
    "Yeah, well, you know, that's just, like, your opinion, man."

    Comment


    • #3
      ^^^ The Dude is right!

      It looks to me from the readings you posted the PT is fine, put it back and pull rectifier tube and output tubes, still blowing fuses?

      Comment


      • #4
        https://www.premierguitar.com/articl...ormer-tester-1

        give it a try.

        Comment


        • #5
          As to your second question, if the 680V winding is shorted, you won't be able to use the 540V tap either.
          "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

          Comment


          • #6
            hey guys, thanks for all the replies. I hooked it up to my current limiter like dude suggested and the bulb lit up like a christmas tree. I guess that says everything, internal short.

            Comment


            • #7
              Well, that's a bummer. It should draw almost no current unloaded.
              "Yeah, well, you know, that's just, like, your opinion, man."

              Comment


              • #8
                ya, it's a bummer for sure. Thanks again for all your help.


                chuck.

                Comment

                Working...
                X