Connect with us

Lenco 600 Transformer identification

Discussion in 'Troubleshooting and Repair' started by habals, May 24, 2017.

Scroll to continue with content
  1. habals

    habals

    4
    0
    May 24, 2017
    Hello Everyone!
    The vinylplayer of my flatmate heated up and there was some smoke coming out. It is a Lenco b55 with a lenco 600 chassis (which is the amplifier). Before this happened, she was using it for almost a year.
    Now I thought if there was smoke there must be a visual damage to the internal parts and it turned out that the transformer melted. The primary side was burned black (and I think that there would have been some ratings). I tried to measure it with the oscilloscope, but it just smoked some more :). The rest looks fine!

    I now found an old manual (as this device is from the 1970s i think) but i can't really figure out what transformer to use! Can someone help me identify the ratings?

    I've also seen that one fuse was shorted (on the amp side) and for the other, the wrong fuse was in place. But still there is the open question why it was working so long and well, but then wasn't anymore.

    I thought that I will just replace the transformer and put in the right fuses and then see how it goes...

    thank you very much for all your answers/suggestions/help :)
     

    Attached Files:

  2. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    There is a 6V bulb connected to the transformer so a 6V (1A ?) transformer would be wanted.
    The smoking may be due to the rectifier or smoothing being faulty. Just fitting a new transformer may just give more smoke.
     
    davenn likes this.
  3. habals

    habals

    4
    0
    May 24, 2017
    Thanks for that info! Jet another question appeared. If I fit an 1A transformer, does this mean that the transformer cannot handle more than 1A output? Because after the transformer there is an 1.25 A fuse. So the fuse cannot protect the transformer if something on the secondary side is wrong... Or would that even be the idea? :)
    Sorry for all those questions, i'm quite new to this and until now i only go by monkey see-monkey do..

    thanks so much!
     
  4. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    I was mistaken! The 6V bulb has a series resistance so the transformer voltage is much higher than I thought.


    It is only a guess as to the current consumption of the set. You could look up the current capability of the output transistors.
    The fuse needs to be strong enough to charge the capacitors on switch on. You can check the transformer for temperature over a long time. A transformer will be able to provide more than the rated current for a few seconds.
    Get a transformer of the same size (or bigger) as the original, it will have similar capability.
     
  5. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    The voltage table goes up to 30V so a 24V transformer would probably do.
    This is a much bigger and powerful device than I first thought, a picture would have helped, there must be big heat sinks.
     
  6. Bluejets

    Bluejets

    5,025
    1,048
    Oct 5, 2014
    470R has 50mA so around 24v there plus 6v for the lamp so 30vac.
    Is that 40v dc t.p. on the top right rail.....? more likely cap rating, however an indicator.
    x2 for #5.
     
  7. habals

    habals

    4
    0
    May 24, 2017
    Do you really think that it's so powerful? After all, it is only an integrated amplifier that can put out 2 x 6W... And it doesn't look like the heatsinks are very effective. I took some pictures, maybe it helps :). Thank you for your answers so far! Foto am 03.06.17 um 18.57 #2.jpg Foto am 03.06.17 um 18.51.jpg
     
  8. Bluejets

    Bluejets

    5,025
    1,048
    Oct 5, 2014
    Operating voltage is in no way a reference to output power on it's own.
     
  9. duke37

    duke37

    5,364
    772
    Jan 9, 2011
    There is some correlation. A 6V amplifier would have difficulty in producing a watt. The operating voltage is often chosen to use easily available devices so 100V(+/-50V) is about the maximum for a domestic amplifier using 4Ω or 8Ω speakers.

    Many years ago, I was told that electric motors should be approximately 1Ω so for 1MW out you would design for 1000V and 1000A supply. There are many deviations from this for convenience like car starter motors or synchronous electric clocks.
     
  10. habals

    habals

    4
    0
    May 24, 2017
    ok thank you very much!
    I will try with a 30volt transformer and correct fuses and see how it goes.
    thanks again!
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-