Fault
Power Amplifier not powering on.
Initial inspection confirmed that input power protection fuse located in the rear IEC socket had blown.
The fuse was blackened indicating excess current had been drawn.
Replacement fuse F6.3 Amps fitted.
The video shows the undocumented fuse carrier and its design.
The fuse carrier can be inserted either way up to select 120 VAC or 230 VAC operation.
In this particular case the fuse holder was the wrong way round, hence why it blew.
For 230 VAC operation the arrow on the fuse carrier should be on the bottom right as shown
in the video.
The Amplifier was retested and again would not power up.
Attention was payed to the rear of the IEC power socket.
The video shows the 230 VAC wire from the transformer disconnected,
the wire was reconnected and the Amplifier powered up and the speaker protection relays changed over.
Before further testing the Amplifier was powered off and the position of the power transformer adjusted.
Often the fixing bolt will be loose and also the transformer rotated to prevent the primary wires connecting to the IEC socket being too tight, often leading to disconnection.
During initial testing it became apparent that non of the 4 cooling fans were rotating.
The fan should run at max speed constantly, the supply voltage(s) to the fans was checked and was found to be correct at 25 volts off load.
The coils of the fans were all open circuit.
Replacement 3000 RPM 24 V DC 0.25 Amp 80X80X25mm Bi Sonic fans fitted restoring correct operation.
Amplifier fully tested working correctly.
