Crown Pulse 21100 Manuel d'utilisateur télécharger pdf (Page 6)

Pulse Checkout Procedures

1 Dissassembly for Service

2 Checkout Procedures

3 Post Testing Procedure

Observe all Cautions and Warnings when servicing this amplifier

1 Dissassembly for Service

1.1 Main Module Removal

Remove the top cover by removing the two side, two back, and four top screws. Lift up slightly on the rear of the cover,

and then pull it toward the back of the amplifier.

Remove the eight screws that hold the input connectors to the chassis.

Remove the four screws that hold the output jacks to the back panel.

Remove the four screws that hold the circuit board down to the chassis.

Remove nut from green and yellow striped ground wire connected to back panel.

Remove the two screws that hold the IEC filter to the back panel.

Remove all eight screws from underneath the chassis. Grip the front silver handle and gently pull forwards about ½ inch (be

careful; it is a tight fit), and then lift up and away from the chassis.

After removing the PCB from the chassis, discharge the power supply capacitors. For C75 use a 1k/5W resistor. For the bulk

reservoir capacitors, use a 10k/5W resistor.

2 Troubleshooting

2.1 Non-Powered Checks

1. Perform a cursory check of all major items in the power supply i.e. IGBT’s.

2. Locate the flyback diodes D114, D115, D214, and D215 on the main modules and check for indications of a short. If a

short is indicated, this means that an output device or driver transistor in parallel with that diode is shorted, usually not the

diode itself. If an output device is found to be defective, emitter resistors should also be checked. If no output device is found

defective, perform a quick check of driver, pre-driver, and bias transistors.

3. Check driver and pre-driver transistors for shorts or opens. If a fault is found, do an in-circuit static check of all

semiconductors on the main board. If no output device and nothing upstream is found defective, move to power-on checks.

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Crown Pulse 21100 Manuel d'utilisateur Page 6