1. Time for some upgrades in server hardware and software to enhance security and take AK to the next level. Please contribute what you can to sales@audiokarma.org at PayPal.com - Thanks from the AK Team
    Dismiss Notice

NAD 2200 In Protection Mode

Discussion in 'Solid State' started by theoman, Apr 15, 2018.

  1. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    I picked this up today with the matching preamp, when I got home I plugged the amp in and it was in protection mode. I blew out all the dust with air and then hooked it up.
    the unit played for awhile then the right channel went out then in protection mode. it did sound a little muddy but it may have been my grade advents.
    Is there a common problem with them. I did see people replacing the 4 large caps on them.
    IMG_9155.JPG IMG_9156.JPG IMG_9157.JPG
     

     

    Please register to disable this ad.

  2. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    IMG_9163.jpg so far no capacitors bulging or leaking? no burnt smell? I'm going to start with speaker protection relays whats the best way to clean oxidized relays? just contact cleaner?

    Do the tops of the relays snap off?
     
    Last edited: Apr 15, 2018
  3. captnmac

    captnmac Active Member

    Messages:
    123
    Location:
    Huntington Beach, CA
    Those look like the original relays, and yes, the tops open. If gunked up, cleaning will buy a little time, but ultimately you will need to replace. There is a recent thread where replacement with near exact fit is discussed. I have heard that paper between the contacts of the relay works, when doused with Deoxit. Sandpaper can destroy the coating of the contacts.
    upload_2018-4-15_21-58-14.png
    On one of my 2200's, one of the indicated caps went bad, causing R417 to go up in smoke, and the protection circuit to engage. These units are old, and the caps probably should be replaced. Replacing the largest 4 caps may need to be done, but there are no direct replacements. Search and read the threads about alternatives.
     
  4. captnmac

    captnmac Active Member

    Messages:
    123
    Location:
    Huntington Beach, CA
  5. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    I cleaned the relays and now I'm not getting any sound, not even a clicking from the relays. I think I'm going to replace them.
     
  6. slimecity

    slimecity Super Member

    Messages:
    3,079
    Location:
    New Zealand
    If you're not getting a clicking thats more likely to mean that the protect circuit is preventing them from engaging - unless you damaged them when you cleaned them.
     

     

    Please register to disable this ad.

  7. restorer-john

    restorer-john Addicted Member

    Messages:
    6,533
    Location:
    Australia
    Yep. I'd say most NAD 2200s have spent some or all of their time in protection mode. They are a touchy design and most end up vaporising an output stage or two. Commutating rails and a +/-90v min supply so be careful poking around.
     
  8. Ray Gianelli

    Ray Gianelli AK Subscriber Subscriber

    Messages:
    1,112
    Location:
    Lake Worth, FL
    If it's in protection check the output going into the relay for offset. This should indicate which channel you're having trouble with.
     
    slimecity likes this.
  9. Electone

    Electone Well-Known Member

    Messages:
    756
    Location:
    London, Ontario, Canada
    Don't spray contact cleaner or Deoxit willy-nilly into the tops of the relays - it does more harm than good. I honestly believe the best way to take care of bad relays is to replace them, but yours are not engaging because the unit is in protect mode. NAD used excellent circuit designs, but kept the costs low by using cheap parts and cheap labor. Check to see if you have excessive DC offset on the speaker terminals. Download the service manual and start checking voltages.
     
  10. slimecity

    slimecity Super Member

    Messages:
    3,079
    Location:
    New Zealand
    This wont work if the relays arent engaging.
     
  11. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas

     

    Please register to disable this ad.

  12. Electone

    Electone Well-Known Member

    Messages:
    756
    Location:
    London, Ontario, Canada
    Woops, brain fart... :crazy:
     
    slimecity likes this.
  13. restorer-john

    restorer-john Addicted Member

    Messages:
    6,533
    Location:
    Australia
    Did you check the DC level on each channel prior (upstream) to the relays as Ray suggested?
     
    slimecity likes this.
  14. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    Its not in protection mode now just no sound and the relays don't click.
     
  15. captnmac

    captnmac Active Member

    Messages:
    123
    Location:
    Huntington Beach, CA
    Still, not a bad idea to check the DC offset measured before the signal goes into the relays. If offset measured is in the low mV level, then it could just be buggered relays. A decent target is < 100mV. If you get a much higher reading, things could be starting to go south. According to the video, you should change the resistor as well.
     
  16. Electone

    Electone Well-Known Member

    Messages:
    756
    Location:
    London, Ontario, Canada
    I repaired a NAD 3100 with the same issue for a friend. The relays were stuck open. A few solid taps with the back of a screwdriver and they popped on.
     

     

    Please register to disable this ad.

  17. bill114

    bill114 AK Subscriber Subscriber

    Messages:
    284
    Location:
    Seminole, FL
    The resistor value will depend on the resistance of the new relay coil. You want to drop 22v across each of the relay coils. Ohms law to get the current of the circuit with the new relays then use the current to figure the resistance to drop the rest of the supply voltage across R413. Do a google search for the service manual. The manual will also give you the correct values for bias and DC offset.
    The relay you ordered doesn't have the correct pin outs or footprint to work. The current rating is not enough either, IMO (only 5A). I used the relays you bought in my 50wpc NAD 2100.
    I used these http://www.newark.com/imo-precision...dc/relay-automotive-spdt-14vdc-45a/dp/74R1551 in my 2600A which has the same protection circuit layout as your 2200 as in the video above.
    The 240 ohm 2w resistor would be used with the IMO relays.
     
  18. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    will do
     
  19. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    I looked at the pictures and they are all deferent but I did get it from this thread and he did replace the resistor. I did buy it from both places.
    http://audiokarma.org/forums/index.php?threads/nad-2200-help.265844/

    and your correct the part number on the other thread is incorrect.
     
    Last edited: Apr 18, 2018
  20. theoman

    theoman Confused Member Subscriber

    Messages:
    2,087
    Location:
    Cypress Texas
    Replaced the relays and fired it up. the units been running smooth for hours. I notice on the wiring diagram the rail voltage in +95v wow. should I go back a check the voltages?
    IMG_9267.JPG IMG_9268.JPG
     

Share This Page