Quote:
Originally Posted by Apfelmus
If its a problem with the transformer, like temperature-dependent shorted windings, shoundn't the current increase appear rather suddenly and not as progressive?
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Yes, I've wondered about this...
Could there be a problem with the control circuit? I've had problems with the Telequipment circuit - caused by high-value resistors (less likely here, as I'm sure Tek would have used HV types) and also by the transistors in the feedback loop. If the transistors are socketed, quickly checking them by substitution is easy.
If you haven't already, it might be interesting to monitor the 248V rail as the unit starts to trip. If the input current rises while the 248V stays constant, that would suggest that the loop is correctly trying to regulate in the face of something trying to change. If the 248V rail starts to rise just before it trips, perhaps that points to the regulator loop?
Always difficult separating out cause and effect
