68kMLA Classic Interface

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LC TDK PSU issues

Posted by: marmotta on 2018-04-23 06:00:30 Solved! Is a thyristor ;-)

Posted by: Miguel on 2020-03-14 16:07:27 Solved! Is a thyristor ;-)   Hi, I have this same PSU and I think this component is bad. When I turn it on, it clicks (indicating overcurrent, it runs for 9ms and stays off for 95ms). The -5V line seems good (charges and discharges with the pulses). The +5 and +12 lines though, have the same waveform on an oscilloscope: A flat line with slightly higher voltage on the pulses (600mV-off time, 800mV-on time). This suggests that the overcurrent is happening in one of these lines. As this component gets quite hot, I am identifying it as the culprit. But I have a few questions: What's a thyristor doing in a PSU? Were you successful in replacing it?

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