Sleeping Sickness: or how to use your standby

[TheWinterSnow]

it is good to turn the standby on before you shutdown the amp because is allows the charges in some of the capacitors to drain, that wouldn't drain if you completely shut down the amp. You will find that if you turn off the power without the standby and read the voltages on the caps they will still be live. Generally if your amp has two lights on them, one for power and one for standby, when you turn on the standby, wait for the LED to drain and turn off, then turn off the main power, since most of the big filter caps are connected to the standby LED, when the LED turns off, you know the caps have drained. Leaving a high charge on a cap wears it down or weakens the dielectric material which can cause the cap to short out and it becomes conductive.

when turning one, use the standby to warm up the tubes for about 30-60 seconds, then turn off the standby. When turning off the amp, use the standby to allow the caps to drain, when the standby LED goes off, and then turn off the amp. As a general rule of thumb, never leave the amp with the standby on for more than a few seconds unless you like paying for new tubes all the time.

 

[Omega_Void]

Standby on power-up is not really necessary, as cathode-stripping does not happen at the 300 volts or so you'd have on the triodes, and at the 500 volts or so on the power tubes the tubes will have worn out and need replacing before any significant cathode-stripping occurs.

it is good to turn the standby on before you shutdown the amp because is allows the charges in some of the capacitors to drain, that wouldn't drain if you completely shut down the amp.

Standby on shutdown is a good precaution, although it's really only necessary if the amp does not include a bleeder resistor in the PSU.

You'll notice most hi-fi valve amps don't have standby switches.

Actually, I've seen a couple of Mesa schematics where the standby came after the reservoir caps and bleeder. Kind of a worst of both worlds since if you switched the amp off too soon after putting in standby the local bypass electros would not be able to discharge through either the tubes or the bleeder resistor.