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Bumble Bee capacitors: Difference between revisions
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# 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. | # 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: Discharge the capacitor. Calculate the frequency at which the reactance of the capacitor should be 0.1 Ω. Set a 50 Ω signal generator to that frequency and an amplitude of 1 V. Connect the signal generator to the capacitor. Probe the voltage across the capacitor with a good oscilloscope. There should be less than 100 mV of AC voltage across the capacitor. | # Measure the ESR: Discharge the capacitor. Calculate the frequency at which the reactance of the capacitor should be 0.1 Ω. Set a 50 Ω signal generator to that frequency and an amplitude of 1 V. Connect the signal generator to the capacitor. Probe the voltage across the capacitor with a good oscilloscope. There should be less than 100 mV of AC voltage across the capacitor. | ||
# If the capacitor passes these three tests, it is probably OK, and the lifted terminal can be | # If the capacitor passes these three tests, it is probably OK, and the lifted terminal can be re-soldered. It is a good idea to somehow mark the capacitor as having been checked. | ||
An easier way to test these capacitors for value, leakage and ESR is with an instrument that performs all three functions, such as a Sencore LC75. A benefit of using the Sencore is that leakage can be checked at the operating voltage of the capacitor, up to 600 V with the Sencore LC75, and up to 1000 V with the Sencore LC101. | An easier way to test these capacitors for value, leakage and ESR is with an instrument that performs all three functions, such as a Sencore LC75. A benefit of using the Sencore is that leakage can be checked at the operating voltage of the capacitor, up to 600 V with the Sencore LC75, and up to 1000 V with the Sencore LC101. | ||
Few vintage RC bridge testers offer Capacitor Leak testing as well, like EICO 950B, Heathkit IT-11, Heathkit IT-28, Heathkit C-3 Condenser Checker etc. These instruments supply up to | Few vintage RC bridge testers offer Capacitor Leak testing as well, like EICO 950B, Heathkit IT-11, Heathkit IT-28, Heathkit C-3 Condenser Checker etc. These instruments supply up to 600 V DC (IT-11) and indicate the leakage current in a Magic Eye Tube. A Closed eye indicates excessive leakage current. | ||
==Pictures== | ==Pictures== | ||
<gallery> | <gallery> | ||
Bumble_Bee_Insulation_Test.jpg | Insulation | Bumble_Bee_Insulation_Test.jpg | Insulation resistance testing of a Bumblebee cap using TO-5 | ||
Capacitor LeakTesting.jpg | Leak | Capacitor LeakTesting.jpg | Leak testing a Bumblebee cap using an EICO 950 B | ||
Tek-RM35A-HV-Section.jpg | Black Beauty | Tek-RM35A-HV-Section.jpg | Black Beauty cap inside a Tek [[535]] HV section | ||
</gallery> | </gallery> | ||
[[Category:Repair issues]] | [[Category:Repair issues]] | ||
[[Category:Capacitors]] | [[Category:Capacitors]] | ||