Perhaps he is living up to his name....
There will be a bias pot for each channel. You can read the voltage off
of the emitter resistors of the output transistors which I recall to be 1 ohm.
Check several of them. The S450e has 6 of those in parallel, so the
bias current with the 1 ohm resistor is 6 times the voltage you read.
.1V = .6 amps bias
You will want to be careful, as you can damage the amp or yourself
doing something like this. Make adjustments in small steps and allow
the amp to sit with the cover on for a while before re-checking.
Best advice - bribe a technician to do it for you.
There will be a bias pot for each channel. You can read the voltage off
of the emitter resistors of the output transistors which I recall to be 1 ohm.
Check several of them. The S450e has 6 of those in parallel, so the
bias current with the 1 ohm resistor is 6 times the voltage you read.
.1V = .6 amps bias
You will want to be careful, as you can damage the amp or yourself
doing something like this. Make adjustments in small steps and allow
the amp to sit with the cover on for a while before re-checking.
Best advice - bribe a technician to do it for you.
You may want to buy the rubber high voltage gloves technicians use on electric/hybrid cars. You can find them at most electric supply stores.
They are bulky and uncomfortable, your hands will sweat inside them, however, it sure beats accidentally touching 78 vdc, That kind of early retirement is not what it's cracked up to be.
They are bulky and uncomfortable, your hands will sweat inside them, however, it sure beats accidentally touching 78 vdc, That kind of early retirement is not what it's cracked up to be.
What voltage do I have to have in each of the 1ohm resistors?
I would start with .1V and see how hot that gets the amp.
And you can use the following guide to get to 50 deg C.
Attachments
Just got a couple of SA-2 that run a bit cold to the touch.
I am planning to inspect them and adjust the bias if needed.
Would anyone be able to confirm that 150mV is the correct value for the voltage drop across the emitter resistors?
Thank you in advance for any help.
Marco
I am planning to inspect them and adjust the bias if needed.
Would anyone be able to confirm that 150mV is the correct value for the voltage drop across the emitter resistors?
Thank you in advance for any help.
Marco
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