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Nad 3045 tune-up

Discussion in 'Solid State' started by Audi0, Aug 9, 2018.

  1. Audi0

    Audi0 Super Member

    Messages:
    1,169
    Just picked this nad 3045 up and it needs a few small things. Somebody peeled the original vinyl wrap off leaving low grade
    Mahogany behind? Maybe I can work with it. The vu meters have lights in them that are burnt out. How does one take them apart? Power switch is arcing out on occasion so ordered a new tv5 push button switch. Wired the switch for on all the time for now.

    Is this a correct snubber circuit? It looks like it would it would be constant voltage overriding the switch???
    20180809_101656.jpg
    20180809_100806.jpg

    The case

    20180808_081447.jpg

    Vu Meters
    20180809_100836.jpg
     

     

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  2. Audi0

    Audi0 Super Member

    Messages:
    1,169
    Well I done messed this up. The leds exploded 3 times there rated for 2.7 volts a piece.

    Somebody explain this to me. I'm doing something wrong. Is the smoother installed right and if the diode was in backwards nothing would turn on right?

    20180809_172157.jpg
     
  3. teal'c

    teal'c It's all moo Subscriber

    Messages:
    15,710
    Location:
    Michigan, N of Detroit
    You have AC LEDs?
     
  4. Audi0

    Audi0 Super Member

    Messages:
    1,169
    I was trying to convert ac to dc. Cheaply. Couldn't find the ground so.
    I slammed a wire into a ground in a electrical socket. Then tried to find the ground on the transformer by putting one side at a time dissconnected on that wire to find the ground as I was getting weird readings. The findings are 8 ac volts the other 6 ac. Very confused.
    I should have a wire that has 0 volts.
     
  5. century tek

    century tek Super Member

    Messages:
    3,280
    Location:
    The Evergreen State
    Don't use the diode after your 6.4 volt. Changing it to dc ups the voltage a little more so you might have been getting 6.8 or 6.9 volts or so on your 2.7 volt LED's. :yikes:

    EDIT: I overlooked your 5Ω resistor.

    You can use the LED's in the AC circuit. You just need to use a resistor to lower the voltage. Some Ohm's law and a little math will tell you what you need.

    The capacitor across the switch doesn't bypass it. It prevents unwanted pops and helps protect the switch contacts from arcing when powering up.
     
    Last edited: Aug 9, 2018
  6. Audi0

    Audi0 Super Member

    Messages:
    1,169
    Is the smoother cap installed right though? Its out in parallel instead of series?

    The goal is to convert ac to dc to get rid of the flicker. The reason the diode is there is to make a half wave.

    My main concern is I have 2 positive lines that make a circuit. This baffles me.
     

     

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  7. redk9258

    redk9258 Super Member

    Messages:
    1,530
    Location:
    Illinois, close to St. Louis.
    Shouldn't the resistor be after the cap?
     
  8. century tek

    century tek Super Member

    Messages:
    3,280
    Location:
    The Evergreen State
    I don't get any flicker with the LED's I am using. You got flicker?
     
  9. Audi0

    Audi0 Super Member

    Messages:
    1,169
    Leds do get 60 cycle flicker so I am trying to rectify that. Some people see it some people don't.
     
    Last edited: Aug 13, 2018
  10. Audi0

    Audi0 Super Member

    Messages:
    1,169
    Ok so I rebuilt the lighting circuit.

    Went to calibrate the needles and the amp is doing the strangest thing. Its singing back at me. Anywhere past 12 o'clock on the dial I can hear the source being played back by components in the amp. Yes its the amp there's no speakers hooked up.

    20180811_184250.jpg 20180811_184437.jpg
     
    Last edited: Aug 12, 2018
  11. Audi0

    Audi0 Super Member

    Messages:
    1,169
    The issue is the disc caps are squealing and making noise on exactly to what the source is. Can somebody explain this to me. I've never seen this before. I could replace the disc caps. Why would a disc cap do this?
     

     

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  12. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,118
    Location:
    West coast
    couple of points

    transformers
    1. unloaded measures higher AC
    2. put a load on and the AC drops

    Caps
    1. 200uf in a disc - unlikely (post clear pix - no iPhone shots)

    led voltages
    1. get specs for LED, voltage and current when lit (conducting)
    2. typically 2-5 volts and typically 10-30ma. verify your LEDs specs against this.

    dropping resistors
    1. if source is 6v and your LED needs 3V, you need to drop 3V
    2. the current is .015 amp for typical LED
    3. ohms law says drop 3v for 0.015 amp
    4. E=IR, so r=e/I
    5. R= 3v to be dropped / (across 0.015amp) = 200R
    6. OR about 80R per volt for this 0.015amp LED
    7. inversely proportional for different currents
    8. lazy like me, wire in pot, dial to correct luminosity and measure pot, replace with resistor

    circuit
    1. are you absolutely positive it is an unused transformer tap? (unlikely in commercial amp)
    2. if not any draw using that transformer tap could cause your problem.
    3. pictures (clear and large) will help
    4. location, location, location. your simple diode circuits leaks/dumps extra goodies as
    it transitions from conducting to not and vice versa.

    PM me if you need LEDs since you're converging on a solution by testing.


    post pics, 200uf in a disc cap? unlikely.
     
  13. Audi0

    Audi0 Super Member

    Messages:
    1,169
    I was talking about what I think is the combination of the pre/power on one board.
    Sorry about the confusion. I found 3 which are playing back to what the source is. There each marked 104. So something small like .0104mfd?

    20180812_193219.jpg
     
  14. Audi0

    Audi0 Super Member

    Messages:
    1,169
    So yeah I've been trying to learn and don't know enough about electronics circuits.
    Been watching YouTube and reading a lot
    Of threads. A lot of the theory is straight up confusing to me. If you know how to make the circuit better let me know I can build it.
    Here is my logic to the circuit I made. Which may on not be wrong.
    20180810_181627.jpg
     
  15. Bob

    Bob AK Subscriber Subscriber

    Messages:
    2,118
    Location:
    West coast
    104 = 10 with 4 zeroes = 100000 = 100nf = .1ufd.

    combination of the pre/power? pre/power what? capacitance? voltage?
    a 104 plus a 205 is not a 309, but is equal to a 215.

    what is "I found 3 which are playing back to what the source is."?
    3 what?
    playing back?

    I highly recommend not watching youtube but reading a basic electronics book
    that covers everything from basics up. youtube creators of various videos
    take short cuts, make assumptions about what you know, and you only get 10%
    of what they're trying to convey, and very pinpoint subjects not enough for here.

    OTOH, youtube is wonderful for upgrading a mid-2009 MacBook pro to High sierra
    when that model is ceilinged by apple to El Capitan. ALL the videos that do this
    in 10 minutes assume you know the MacOS at the coding level, can write/modify
    shell scripts at the Unix level, and can follow deep technical topics.
     

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