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Amplifier board debugging notes (view source)
Revision as of 19:49, 30 March 2010
, 19:49, 30 March 2010Created page with 'This page contains a list of all currently known problems with the amplifier board and the solutions implemented = Problems = == Improper DC levels from voltage regulators == …'
This page contains a list of all currently known problems with the amplifier board and the solutions implemented
= Problems =
== Improper DC levels from voltage regulators ==
=== Description ===
Incorrect voltage levels on the basis of the transistors representing the input stages for base amplifier and summing circuits.
=== Cause ===
The pads for pins Gnd and Vz of the voltage regulators were reversed. The proper assignment of pins is shown in the adjacent figure.
=== Solution ===
* the ICs were rotated such that 2 pins (Vref and Gnd) are bonded to their nets. The loose Vz pin was connected via wire to its proper proper net.
* '''modifications of the PCB layout is pending'''
== Wrong voltage on R<sub>C</sub>/R<sub>D</sub> junction ==
=== Description ===
A voltage of 2.75 V was measured on the junction between R<sub>C</sub> and R<sub>D</sub> resistors, instead of 2.25
=== Cause ===
Resistors R<sub>C</sub> and R<sub>D</sub> (2.5 kΩ and 2.0 kΩ respectively) have been reversed. The is an error on the layout: the placement designation and the silk-screen labeling is wrong.
=== Solution ===
* The resistors have been swapped.
* '''modifications of the PCB layout is pending'''
== FET switch compatibility ==
=== Description ===
The FET switch BF1108 was not available in our market. Only its mirror package variant BF1108R could be procured.
=== Solution ===
* ''Temporary solution'': The adaptation of the board for the BF1108R is shown in the adjacent figure. The IC is positioned in the shown orientation and its pins (pads) linked as shown.
* '''modifications of the PCB layout is pending'''
= Problems =
== Improper DC levels from voltage regulators ==
=== Description ===
Incorrect voltage levels on the basis of the transistors representing the input stages for base amplifier and summing circuits.
=== Cause ===
The pads for pins Gnd and Vz of the voltage regulators were reversed. The proper assignment of pins is shown in the adjacent figure.
=== Solution ===
* the ICs were rotated such that 2 pins (Vref and Gnd) are bonded to their nets. The loose Vz pin was connected via wire to its proper proper net.
* '''modifications of the PCB layout is pending'''
== Wrong voltage on R<sub>C</sub>/R<sub>D</sub> junction ==
=== Description ===
A voltage of 2.75 V was measured on the junction between R<sub>C</sub> and R<sub>D</sub> resistors, instead of 2.25
=== Cause ===
Resistors R<sub>C</sub> and R<sub>D</sub> (2.5 kΩ and 2.0 kΩ respectively) have been reversed. The is an error on the layout: the placement designation and the silk-screen labeling is wrong.
=== Solution ===
* The resistors have been swapped.
* '''modifications of the PCB layout is pending'''
== FET switch compatibility ==
=== Description ===
The FET switch BF1108 was not available in our market. Only its mirror package variant BF1108R could be procured.
=== Solution ===
* ''Temporary solution'': The adaptation of the board for the BF1108R is shown in the adjacent figure. The IC is positioned in the shown orientation and its pins (pads) linked as shown.
* '''modifications of the PCB layout is pending'''