Bumble Bee capacitors: Difference between revisions

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* The capacitor's equivalent series resistance (ESR) can increase significantly.

Each of these problems can be checked for using basic test equipment. It is time-consuming, but if, for example, one is determined to keep an instrument as original as possible, the following ~~procedure~~ will find most of problems with black beauty capacitors.

Each of these problems can be checked for using basic test equipment. It is time-consuming, but if, for example, one is determined to keep an instrument as original as possible, the following sequence of steps will find most of problems with black beauty capacitors. If, at any step, the measurements are bad, the capacitor is bad and it should be replaced.

1) ~~Remove~~ one end of the capacitor from the surrounding circuit.

1) Lift one end of the capacitor from the surrounding circuit. Follow the soldering instructions in the manual.

2) Check for DC leakage: To do this, you will need a DC power supply that has current limiting and goes up to the operating voltage of the capacitor. Disconnect one end of the capacitor. Attach an sensitive ammeter in series with the power supply and the capacitor, and bring the power supply up to operating voltage of the capacitor.

2) Check for DC leakage: To do this, you will need a DC power supply that has current limiting and goes up to the operating voltage of the capacitor. Disconnect one end of the capacitor. Attach an sensitive ammeter in series with the power supply and the capacitor, and bring the power supply up to operating voltage of the capacitor. The DC leakage should be less than 3uA.

3) Check for drift in capacitance: Discharge the capacitor. Measure it with a capacitance meter.

3) Check for drift in capacitance: Discharge the capacitor. Measure it with a capacitance meter. If it is outside the original tolerance range, it should be replaced.

4) Measure the ESR: (to be ~~continued~~)

4) Measure the ESR: Discharge the capacitor. Calculate the frequency at which the reactance of the capacitor should be 0.1 ohms. Set a 50-ohm signal generator to that frequency and an amplitude of 1 volt. Connect the signal generator to the capacitor. Probe the voltage across the capacitor with a good oscilloscope. There should be less than 10mv of AC voltage across the capacitor.

5) If the capacitor passes these three tests, it is probably OK, and the lifted terminal can be resoldered. It is a good idea to somehow mark the capacitor as having been checked.

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 * The capacitor's equivalent series resistance (ESR) can increase significantly.
-Each of these problems can be checked for using basic test equipment.  It is time-consuming, but if, for example, one is determined to keep an instrument as original as possible, the following procedure will find most of problems with black beauty capacitors.
+Each of these problems can be checked for using basic test equipment.  It is time-consuming, but if, for example, one is determined to keep an instrument as original as possible, the following sequence of steps will find most of problems with black beauty capacitors.  If, at any step, the measurements are bad, the capacitor is bad and it should be replaced.
-) Remove one end of the capacitor from the surrounding circuit.
+) Lift one end of the capacitor from the surrounding circuit.  Follow the soldering instructions in the manual.
-) Check for DC leakage: To do this, you will need a DC power supply that has current limiting and goes up to the operating voltage of the capacitor.  Disconnect one end of the capacitor.  Attach an sensitive ammeter in series with the power supply and the capacitor, and bring the power supply up to operating voltage of the capacitor.
+) Check for DC leakage: To do this, you will need a DC power supply that has current limiting and goes up to the operating voltage of the capacitor.  Disconnect one end of the capacitor.  Attach an sensitive ammeter in series with the power supply and the capacitor, and bring the power supply up to operating voltage of the capacitor.  The DC leakage should be less than 3uA.
-) Check for drift in capacitance:  Discharge the capacitor.  Measure it with a capacitance meter.
+) Check for drift in capacitance:  Discharge the capacitor.  Measure it with a capacitance meter.  If it is outside the original tolerance range, it should be replaced.
-) Measure the ESR:  (to be continued)
+) Measure the ESR:  Discharge the capacitor.  Calculate the frequency at which the reactance of the capacitor should be 0.1 ohms.  Set a 50-ohm signal generator to that frequency and an amplitude of 1 volt.  Connect the signal generator to the capacitor.  Probe the voltage across the capacitor with a good oscilloscope.  There should be less than 10mv of AC voltage across the capacitor.
+) If the capacitor passes these three tests, it is probably OK, and the lifted terminal can be resoldered.  It is a good idea to somehow mark the capacitor as having been checked.

Bumble Bee capacitors: Difference between revisions

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