CTs 3000 Fuse Location

2 posts in this topic

Hello Maury,

There is 'no' mains fuse per se : there is an active 'breaker' that acts like a fuse for when the mains current overloads the system.

With the help of the 'Soft Start' circuit in the SMPS, an overall systems check is first performed at power up.

The initial mains current flows through some PTC (positive temperature coefficent) resistors (in parallel with an open SS relay) until the SS relay is activated and the PTC resistors are bypassed, and the PTC behavior is removed and the full power of the mains is available to the amp. The smps (sample mode power supply) has now been activated, power is now available to the secondary systems and the SS relay enabled only once the smps is secured.

If the current passing through the PTCs is too high, for instance (because of an output fault, for instance) the SS relay won't be activated and the 'full' mains voltage will be blocked by the high impedance of the PTC resistors. The smps is not in operation but in stand by mode : waiting for the output fault to disappear, in this case. Of course, the fault doesn't go away unless it is removed and repaired.



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