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| LC1 with dead power supply |
Posted by: Unknown_K on 2011-12-15 15:54:11
I got an original LC I in today that was dead (you can hear a low level clicking in the supply). Swapped the PS for one out of an LC III and it started up. So I took the dead PS apart and the fuse is fine, no burn marks or signs of over heating or popped caps. Any idea what is wrong with the PS, any common points of failure?
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Posted by: techknight on 2011-12-15 17:54:14
"ticking" is because of either a shorted secondary voltage rail, or simply bad capacitors. when it "ticks" its because the regulation feedback trips and shuts down the PWM controller in most cases, Overvoltage, undervoltage, overcurrent, etc are different conditions that can trip the feedback. Also any faults in the feedback will cause a false-trip.
the ticking is actually the lockout mode on the PWM circuit kicking in, it waits for a time constant capacitor to discharge beyond a point, and the PWM cycle restarts again. once again, if it overshoots or locks out, the process repeats.
Of course, theres also the fact that the PWM oscillator could be running THAT slow because of a failed capacitor, but it isnt common, its more common to hear a LOUD ring in the audible frequency range from a fault in that type of circuit.
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Posted by: olePigeon on 2011-12-16 10:18:57
I may have an extra LC power supply you can have free for the cost of shipping.
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Posted by: Unknown_K on 2011-12-31 22:27:56
Is that power supply still available? Never heard anything from my PM.
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Posted by: onlyonemac on 2012-06-10 08:38:18
Is the ticking constant or one-off? I ask this in the intrest of the other users who can help you.
:lc: :quadra: :ii:
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Posted by: techknight on 2012-06-11 18:15:23
the ticking would be consistent with the DTC network of the power supply.
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