Inside the head you should inspect the under side of the electronic board. Be careful of the high voltage. After a few days of being unplugged you may remove this board. Check for rings around any transistor or IC with heat sinks and resolder as needed. And have someone check those capacitors for you...A weak cap will hiss! Also check the grounds on those large resistors of 2 watts or more. This should be a good start for repair! Good Luck!
A relatively quiet "hiss" is normal and is due to the statistical properties in electronics. If the level is noticeable during normal program play, then it needs to be dealt with.
First thing is to verify the noise is still there with NOTHING plugged into the input jacks. Many times the noise comes from bad cables and guitars that have noisy on-board electronics, so we must check this out by unplugging all inputs.
MAKE SURE any other devices connected to this that require connections to the power input ALL are plugged into the same receptacle.
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Inside the head you should inspect the under side of the electronic board. Be careful of the high voltage. After a few days of being unplugged you may remove this board. Check for rings around any transistor or IC with heat sinks and resolder as needed. And have someone check those capacitors for you...A weak cap will hiss! Also check the grounds on those large resistors of 2 watts or more. This should be a good start for repair! Good Luck!
A relatively quiet "hiss" is normal and is due to the statistical properties in electronics. If the level is noticeable during normal program play, then it needs to be dealt with.
First thing is to verify the noise is still there with NOTHING plugged into the input jacks. Many times the noise comes from bad cables and guitars that have noisy on-board electronics, so we must check this out by unplugging all inputs.
MAKE SURE any other devices connected to this that require connections to the power input ALL are plugged into the same receptacle.