How To Add A Bias Pot To A Guitar Amplifier

Wear and tear means that there is a need to know how to add a bias pot to a guitar amplifier. The process has to be done earlier to prevent permanent damage to the system. The operative needs to have a basic understanding of how the system works in order to be successful in the venture. 

In order to simplify what can be a technical process, the reader will need to come up with the following items:

  • A circuit diagram of the amplifier system
  • A pen and a writing pad
  • Flat head screwdrivers
  • Markers
  • De-soldering agents
  • Soldering iron and a multi meter
  1. Ascertain the different components of the bias pot and amplifier: The power ratings of the program will be directly related to the power dispersion. Idle current will need to be compared with the voltage as well as the amplifier class. Furthermore, the amplifier should be laid out on the work surface with the grille unscrewed. The transformers on each side of the amplifier cabinet will need to be removed and the circuitry lifted. The power tubes will then be removed. The amplifier should be resting on the transformers at this stage.
  2. Soldering processes in order to add a bias pot to a guitar amplifier: The ground wire will need to be de-soldered together with an OHM resistor by twisting the wire around the exposed section. The amplifier will need to be switched on and then put on standby. The maximum DCV reading will have to be recorded. A reading will be taken from pin 5. The bias control should be put back to -80v. The tubes are then reinstalled and put on standby.
  3. Amplifier reconnection in the process to add bias to a guitar: The amplifier is plugged into its socket until it fits snugly. The amplifier is then taken out of the standby position and the DCV put back on the highest level. A reading will have to be found between the chassis and the pin 3. The information is then recorded for later use. The multi meter is then put on the lowest DCV scale and the OHM resistor recorded. The bias will then be adjusted to 35 MA.
  4. Computations and other final process in adding bias to a guitar amplifier: The voltage will have to be multiplied by the OHM resistor reading. The specification will provide a good example of the expectations. Twenty watts is the maximum that is expected. The meter is then set to the highest DCV scale. The lower reading taken should be taken to ensure that the plate voltage is dropping accordingly. Idle wattage is obtained by checking the readings without any resistance.
  5. Testing the bias pot on the guitar amplifier: The guitar will then have to be plugged into the AMP. The controls should be adjusted for the best sound. When this level is achieved, then the guitar can be removed.
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