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Resistor size

Discussion in 'Amp Tech Center' started by mefgames, Jan 22, 2021.

  1. mefgames

    mefgames Friend of Leo's Double Platinum Supporter

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    I just started building an OSD amp Kit I bought 3 years ago. I was short a resistor, so I ordered an assortment. When they arrived today, I opened them to find they are smaller than the ones that came with the kit. The banding codes are correct as to value, but is there any reason I shouldn’t use them ?
     
  2. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Depends where it is in the circuit, so we'd need more details. Size=wattage. If it's the 68K input resistors or something like that, it doesn't matter. If it's in the power supply section, it could matter a lot. If you can give us some context we can help :D
     
    SRHmusic and King Fan like this.
  3. King Fan

    King Fan Poster Extraordinaire Ad Free Member

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    For sure.... Size signifies wattage in standard old 20th-century resistors, but we've been seeing threads here recently (and I had one a while back) where unsuspecting consumers ordered up ½W resistors and got something the size of a small ant. Dunno, but I assume the cellphone / miniaturization era is producing smaller form factors for the same wattage?
     
  4. DADGAD

    DADGAD Friend of Leo's

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    Half watt resistors are rated for 350 volts. 1 watt resistors are rated for 450 volts. Don’t use 1/4 watt resistors for plate, screen or power supply dropping resistors.
     
  5. mefgames

    mefgames Friend of Leo's Double Platinum Supporter

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    It's a 1/2 watt 5.1K resistor. I mistakenly bought an assortment of 1/4 watts. The resistor goes into V5 to pins 5 and 6. I contacted the Kit manufacturer and he said the 1/4 watt would be fine, but I really prefer to use what it calls for. It's a 22/33 watt OSD kit.
     
  6. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    What is V5? Could you post a schematic?

    If the kit manufacturer said it's good, that would be good enough for me :D
     
  7. mefgames

    mefgames Friend of Leo's Double Platinum Supporter

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    valve 5,
     
  8. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Hahahah - I meant the function in the amp.
     
  9. tele_savales

    tele_savales Tele-Holic Platinum Supporter

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    NICE!
     
  10. mefgames

    mefgames Friend of Leo's Double Platinum Supporter

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    Sorry,
    Power tube, 6L6 or 6V6 switchable
     
  11. corliss1

    corliss1 Friend of Leo's Platinum Supporter

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    Pin 6 is being used as a convenient place to solder things together, as that pin is not used in the 6v6 or 6l6. The actual pin may not even be present on the tube. Same with pin 1.

    It's the grid resistor for the tube which we can see here (taken from a deluxe reverb, but every amp is pretty much the same)

    Screen Shot 2021-01-22 at 11.51.09 PM.png

    In this example, pin 5 is the 1500 ohm resistor pictures on both power tubes.

    There's not really any power handling there, but being attached to a power tube they will get hot just from the ambient heat of the amp, if they are mounted right at the socket.

    Personally, I only order 1W resistors so I don't have to worry about this :D. 1/4W would be fine as that really is not drawing any amount of current in that location, but they are so tiny and a pain to work with.

    Go ahead and put them in :D If it makes you feel better, order something bigger.
     
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