When troubleshooting transistors i have found they test good using the DVM meter diode check mode. No opens or shorts and I get .7 volts from base to emitter and base to collector. So i use to think the transistor was good and would resolder it back in the circuit. The problem with these transistors is they pass at low test voltage but not at high test voltage. I'm guessing the transistors are conducting at lower voltages but not conducting at a higher voltage.
I used an external power supply set at +28volts and used my DVM meter set to measure DC volts. The Negative of the power supply goes to the N-junction and the Positive of the power supply goes to the P-Junction. I measure the voltage from base to emitter and from base to collector and from emitter to collector. I should get .7 volts from base to emitter and base to collector if the transistors good even if the external power supply is set at +28volts?
When testing a Diode is the same way, just connect an external power supply across the diode and measuring the DC voltage "across" the diode using a DVM meter set to measure DC voltage. If the diode is good you will measure .7 volts even if the external power supply across the diode is set at +5 thur +12volts?
I used an external power supply set at +28volts and used my DVM meter set to measure DC volts. The Negative of the power supply goes to the N-junction and the Positive of the power supply goes to the P-Junction. I measure the voltage from base to emitter and from base to collector and from emitter to collector. I should get .7 volts from base to emitter and base to collector if the transistors good even if the external power supply is set at +28volts?
When testing a Diode is the same way, just connect an external power supply across the diode and measuring the DC voltage "across" the diode using a DVM meter set to measure DC voltage. If the diode is good you will measure .7 volts even if the external power supply across the diode is set at +5 thur +12volts?