Question about Sony STR-DE545 Receiver
You probably have shorted rectifiers and/or transistor(s) on standby board. Trouble-shoot rect bridge and cap. Feel stand by circuit transformer for abnormal heat, sure sign
Posted on May 01, 2008
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Please check the power supply to the unit, if the fuse or the main power is faultty. Now if the set has tripped then this can be a protection fault condition. The fault can be your output drivers- the MOSFETS/IC's fitted for both the channels, Use a meter after disconnecting to check for short in the drivers. Disconnect the positive and negative voltages to the output and see if the protect changes. Even a fault in the preamp stages that drives in high current into the output can shut the Amplifier. Sometimes this can be a noise like a HUM or HISS before the protect works. Faulty capacitors in these circuits also can cause similar issues and needs close observation.
You need to confirm and replace the specific stages or outputs. If not there can be issues in the mother board, maybe the protect circuit by itself is shutting off due to a faulty bias , maybe a leak in any voltage/current sensing circuit. Also disconnect the speakers and test, if the protect is off then check for short on the speakers.
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