Announcement

Collapse
No announcement yet.

Flameproof/retardant resistors

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Flameproof/retardant resistors

    Working on a Peavey Classic 50 amp with a blown preamp plate resistor (R60 on schematic link below). The original looks like it is probably flameproof/retardant (I'm sure these terms are completely different and I shouldn't use them carelessly, so feel free to educate me).and resistor was mounted up off the board on barrels. On other Peaveys they actually call out FP on the schematic but not on this one (https://www.thetubestore.com/lib/the...-Schematic.pdf).

    So the question is does this need to be FP, and in general when should FP resistors be used?

    TIA,
    Greg

  • #2
    R60 (10k/1W) on that schematic is actually a power supply node resistor- not plate resistor. IMO, there's no reason it needs to be FP, especially since it stands off the board and is unlikely to damage anything if it burns up.
    "I took a photo of my ohm meter... It didn't help." Enzo 8/20/22

    Comment


    • #3
      Usually when I buy 1 watt resistors, I get metal film anyway - flame proof.

      But I agree with Dude, it is just a resistor.
      Education is what you're left with after you have forgotten what you have learned.

      Comment


      • #4
        Works for me, thanks!

        Comment


        • #5
          Metal oxide are good power resistors also.

          Comment


          • #6
            Originally posted by mozz View Post
            Metal oxide are good power resistors also.
            Yup. Especially for tube type circuits because they usually have the right voltage rating. But then the voltage on those resistors is the differential from one end to the other and not the actual voltage of the power supply. Still, I try to use metal oxide for the rail. They usually do have a flame proof, retardant or resistant coating too. Though it's not needed here and I almost prefer plain enamel coating because it gives clear visible signs of an overheating situation.

            JM2C
            "Take two placebos, works twice as well." Enzo

            "Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas

            "If you're not interested in opinions and the experience of others, why even start a thread?
            You can't just expect consent." Helmholtz

            Comment


            • #7
              After having a few Carbon Comp resistors ignite on me wgen I made a wiring error, well, I tend to use anything but unless it's a museum-piece.

              Geez. I forget to even think about voltage ratings half the time. But I tend towards overkill on wattage ratings anyway.

              Justin
              "Wow it's red! That doesn't look like the standard Marshall red. It's more like hooker lipstick/clown nose/poodle pecker red." - Chuck H. -
              "Of course that means playing **LOUD** , best but useless solution to modern sissy snowflake players." - J.M. Fahey -
              "All I ever managed to do with that amp was... kill small rodents within a 50 yard radius of my practice building." - Tone Meister -

              Comment


              • #8
                Huh.
                I never took note of how the B+ and the B++ nodes feed different halves of V1 & V2.

                Comment

                Working...
                X