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Bass Amps & Effects / Re: 1 of 4 screen resistors dead - I have questions
« on: August 24, 2016, 10:54:39 PM »
Might not be a problem to use tubes of different kinds, but as you experienced; they have to be in good shape! As I said earlier, if you suspect a tube have gone bad - replace it. Do not use a valueable amp with bad tubes, you don't wanna ruin it on purpose!
Have your tech measure the tubes and maybe move them around until they pull about the same current.
You could (since you are no stranger to electronics and can use a soldering iron) just install some good 1W1R1% resistors between cathode and ground (depending on the design, but I guess the cathodes here are grounded) and you can easily measure and bias yourself. 1mV = 1mA across the resistor.
Have your tech measure the tubes and maybe move them around until they pull about the same current.
You could (since you are no stranger to electronics and can use a soldering iron) just install some good 1W1R1% resistors between cathode and ground (depending on the design, but I guess the cathodes here are grounded) and you can easily measure and bias yourself. 1mV = 1mA across the resistor.