by M0XXQ » Tue Oct 16, 2018 6:22 pm
Ok well after a full hour of load testing the fault appeared and 17V appeared at the output, followed by the full 24V at the output - failing 2N3055 pass transistor, stripped the PSU down and located the faulty device with a DVM and sure enough 76Ohms between the collector and base in both directions and the collector and emitter gave a low-ish reading.
I will build a crowbar circuit into this PSU as it has no protection for over-voltage.
I shall run it under load at around 13 amps for a good hour to make sure the fault has cleared.
Ok well after a full hour of load testing the fault appeared and 17V appeared at the output, followed by the full 24V at the output - failing 2N3055 pass transistor, stripped the PSU down and located the faulty device with a DVM and sure enough 76Ohms between the collector and base in both directions and the collector and emitter gave a low-ish reading.
I will build a crowbar circuit into this PSU as it has no protection for over-voltage.
I shall run it under load at around 13 amps for a good hour to make sure the fault has cleared.