Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Vlada on November 10, 2021, 10:36:26 am
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My friend gave me a few 1k Mills MRA 12watt resistors. Since they are not flameproof, is it safe to use them as screen grid resistors for EL34 tubes?
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It depends on the detail of the amp really. Schematic? Is there a HT fuse?
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... 12watt resistors. Since they are not flameproof, is it safe to use them as screen grid resistors ...
It depends on the detail of the amp ...
The resistor is rated for 12 watts, the EL34 screen is rated for 8 watts maximum.
Even without looking into how the resistor & screen might share voltage, it seems a safe guess the screen grid will melt before the resistor gets hot enough to burst into flames.
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Thank you guys
Its standard 1987 jmp50, with fuses in different position than standard schematic shows - both primaries now have fuses, before rectifier diodes - advice from valve wizards site
The thing that made me question using higher wattage resistor is recent thread here about 1watt screen resistors used in 5f6a and that they act like fuse
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Ok, if you can fit them them in there, you may as well get some use from them :icon_biggrin:
Bear in mind that they’re grid stoppers too, so it’s preferable to mount them close to the valve socket terminal.
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Space isnt a problem
I am just wondering is it better to use 5watt instead 12watt resistor there :w2:
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What benefit do you perceive for the 5W over the higher power resistor?
Aiken puts an emphasis on the voltage rating, ie that it should be sufficient to (momentarily) accommodate a g2 short.