Patient: Norstar - Plus modular ICS NT7B62FA power supply.
Complaint: Doesn't power up anymore. It did work for a short while, next morning dead?
U1 (UC2844) Vcc pin jumping up and down between 10V and 15V. Vcc supply resistor 51.1k and capacitor 100uf 40V is o.k., but jet there is nothing coming out on the other end. Secondary is producing nothing, no shorts, nothing visible.
Replaced U1 (UC2844) with a new one, powered the PSU up on the bench and the LED started to blink faintly. Plugged the PSU card back into the Norstar modular ICS and all is working fine as kind.
A nice easy Saturday evening repair job.
Can't get much easier than that! 
Complaint: Doesn't power up anymore. It did work for a short while, next morning dead?
U1 (UC2844) Vcc pin jumping up and down between 10V and 15V. Vcc supply resistor 51.1k and capacitor 100uf 40V is o.k., but jet there is nothing coming out on the other end. Secondary is producing nothing, no shorts, nothing visible.
Replaced U1 (UC2844) with a new one, powered the PSU up on the bench and the LED started to blink faintly. Plugged the PSU card back into the Norstar modular ICS and all is working fine as kind.
A nice easy Saturday evening repair job.
Can't get much easier than that!
Attached Files
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