Rotel Explore Protection Circuitry and Troubleshooting for the 985BX Stereo Amplifier

STEREO INTEGRATED AMPLIFIER RA-985BX

Protection Circuitry 3 Troubleshooting

The RA-985BX has both thermal and over-current protection cir- cuitry that protects the amplifier against damage in the event of extreme or faulty operating conditions. The protection circuits are independent of the audio signal and have no impact on sonic per- formance. Instead, the protection circuits monitor the tempera- ture of the output devices and shut down the amplifier if temperatures exceed safe limits.

Most likely, you will never see this protection circuitry in action. However, should a faulty condition arise, the amplifier will stop playing and the LED indicator on the front panel will light up.

If this happens, turn the amplifier off. Let it cool down for several minutes, and attempt to identify and correct the problem that caused the protection circuitry to engage. When you turn the am- plifier back on, the protection circuit will automatically reset and the indicator LED should go out.

In most cases, the protection circuitry activates because of a fault condition such as shorted speaker wires, or inadequate ventila- tion leading to an overheating condition. In very rare cases, highly reactive or extremely low impedance speaker loads could cause the protection circuit to engage.

If the protection circuitry triggers repeatedly and you are unable to isolate and correct the faulty condition, contact your authorized Rotel dealer for assistance in troubleshooting.

Most difficulties in audio systems are the result of incorrect con- nections, or improper control settings. If you encounter problems, isolate the area of the difficulty, check the control settings, deter- mine the cause of the fault and make the necessary changes. If you are unable to get sound from the RA-985BX, refer to the sug- gestions for the following conditions:

Standby Power Indicator Is Not Lit

The Standby Power Indicator should be lit whenever the RA- 985BX is plugged into the wall power outlet. If it does not light, test the power outlet with another electrical device, such as a lamp. Be sure the power outlet being used is not controlled by a switch that has been turned off.

Fuse Replacement

If another electrical device works when plugged into the power outlet, but the Standby Indicator still will not light when the RA-985 is plugged into the wall outlet, it indicates that the internal power fuse may have blown. If you believe this has happened, contact your authorized Rotel dealer to get the fuse replaced.

No Sound

Check the signal source to see if it is functioning properly. Make sure the cables from the signal source to the RA-985BX inputs are con- nected properly. Be sure the Listening Selector is set to the proper input. Check the wiring between the RA-985BX and the speakers.

Protection Indicator Is Lit

The front panel indicator lights when the RA-985BX protection cir- cuits have shut off the amplifier. Typically, this occurs only when the ventilation openings are blocked, when there is faulty speaker wiring, or after a period of extreme use. Turn off the system and wait for the amp to cool. Then push the front panel power switch in and out to reset the protection devices. If the problem is not corrected or re- occurs, there is a problem with the system or the amplifier itself.

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