New resistors for AC30 heritage, what wattage?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by mcdes, Feb 19, 2012.

  1. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    I have gone through the schematic and also looked at them physically.

    I'm looking at ordering some Allen Bradley replacements, and have all the values etc, but what wattage do I need??? Is it all down to size and guessing? Going higher to make sure?

    .5,1,2 watts?? Something different? What say you! Haha

    T.I.A
     
  2. Blue Strat

    Blue Strat Member

    Messages:
    30,036
    Joined:
    Aug 2, 2002
    Location:
    Sterling, VA (not far from Washington DC)
    There are probably a variety of wattages throughout the amp. For the smallest, more prevalent, resistors 1/2 watt should do.
     
  3. phsyconoodler

    phsyconoodler Member

    Messages:
    4,351
    Joined:
    Jul 11, 2005
    Location:
    calgary canada
    And you would want to replace the resistors for what reason????
     
  4. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    Mainly long term reliability. They built these amps in china real cheap, so with my new amp here to take over giggIng duties for a while, I'm going through and replacing a few parts like with like, learning the amp, and about amps.
     
  5. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    And would it hurt if I put higher wattage in there? Just to be safe....
     
  6. diagrammatiks

    diagrammatiks Member

    Messages:
    3,030
    Joined:
    Jan 6, 2010
    are those the old ones that were on pcb?
     
  7. pdf64

    pdf64 Member

    Messages:
    5,188
    Joined:
    Aug 9, 2008
    Location:
    Staffordshire, UK.
    It would be unusual for modern resistors (with a suitable voltage and power rating) to fail; are they known to be a weak point in that Vox?
     
  8. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    None of the above,As stated above, it's a for a semi pointless learning excersize is all.
     
  9. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    Yea, the old 2007 one which was half and half. All the components are turret mounted, but the turrets are PCB mounted.
     
  10. diagrammatiks

    diagrammatiks Member

    Messages:
    3,030
    Joined:
    Jan 6, 2010
    you'll just have to see what fits between the turrets.

    1/2 to 1 watt carbon com should be ok.

    you'll need a bit bigger or a different resistor with higher voltage for the power resistors.
     
  11. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    Awesome, thanks guys.
     
  12. Zerksies

    Zerksies Member

    Messages:
    202
    Joined:
    Feb 13, 2012
    Location:
    Ocean Township, New Jersey
    I would think 1 watt would be more then enough
     
  13. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    just two more questions for my friendly professors around here.....

    1/ what do fresh caps that have not reached 20hours etc, sound like? seems my amp has a slightly flabby low end, normal?

    2/ i got the AB resistors, and yup, they are up a little on the values. most are under just on 10%, one is just on or over 20%. will it change the amp much being out by 10%? or best to 'cook' the resistors to within spec anyway for the 8 hours on 80 deg?
    i got some spray on sealant so when they are cooked, if needed, i can seal them lightly, its clear too so you can still seem em nice resistors and values.
     
  14. Jonnygeetard

    Jonnygeetard Member

    Messages:
    266
    Joined:
    Jun 19, 2011
    You're killing me dude, I really hope you're pulling our leg.
     
  15. mcdes

    mcdes Member of no importance

    Messages:
    7,558
    Joined:
    Oct 9, 2007
    Location:
    New Zealand
    nope, no leg pulling here.......
     
  16. neteraser

    neteraser Member

    Messages:
    2,011
    Joined:
    Jun 15, 2011
    Location:
    St.Petersburg
    No any problem. :)

    Unfortunately, it will. Only replace if the value is OK. This is important.
    Also, 1W A-B resistors are huge... because of that I'd go with another type of resistor in power supply. And in some other places I'd place 0.25W instead of 0.5W. So just make sure you like the result and the value of the resistor is close to what is expected.
     

Share This Page