Standby light is flashing on my marantz sr7001
First of all remove all the speaker connections from the amplifier. After that power the amplifier and check the Standby blinking (protect) show or not . if not, then any of the speaker is damaged also check the wire for any short circuit . If then also its goes to protection then it have some hardware truouble inside.
Amplifiers gose protect mode , when there is a hardware fault in side it. Its a warning that some thing is wrong.
Normally amplifiers show this when any of the output amplifier have some problem. there 6 amplifiers in this receiver . May occur when the output diver transistors of any of the amplifier become shorted. if the output transistor get shorted this will lead to flow of current through the speakers. To prevent this there is a protection circuit for each channels. One combined output of this protection circuit is connected to the system control. when the any of the output amplifier fails, the protection circuit detects it and switch of the speaker and sent data to the system control. when the system control get this data it will give a warning to the customer through display that PROTECT.
You have to check the amplifier.
For that you need digital multimeter,soledring iron screwdrivers etc
Open the amplifier , then power it on. Connect the negative terminal of the multimeter any where in the chase( metal body of the amplifer). Then connect the positive terminal to all the output transistors emitter pin one by one . The voltage should be bellow 0.5V. If any of the emitter of the transistor shows voltage more than +/- 0.5V., then that amplifier stage is faulty. Remove the transistors and check it. if it is shot then replace with a new one.
After replacing the transistors do not power up the amplifier directly from the main. You have to put a bulb of 60 watts in serial.
You can do this easily remove the mains fuse. Put the bulb in a holder. Now you have two wire from the holder. connect one of it to the one end of the fuse holder and the other wire to the other end of the fuse holder. Why using a bulb is, if there is any further problem in the amplifier stage on which the transistors replaced, there is a possibility of the new transistor get damage. if we use a bulb in serial with its mains supply ,when any overload in the amplifier occur the bulb will drop the current, by lighting itself.
After connecting the bulb in serious power on the amplifier. watch the bulb. It should light for one or two second and go dim ,then remove the power , remove the bulb insert fuse and connect the power and check.
(If the bulb shows bright light then there is some component also faulty in the same amplifier. after removing the power you have to check again the amplifier stage of which the transistor is replaced, for any other faulty components
Aug 20, 2011 |