Protect message Recently, when listening to music or when a loud noise was made in a movie  my Marantz Model SR4500 receiver is flashing a protect message and the sound goes off. Sometimes the receiver shuts off completely. Now I can't get any sound from my HD Toshiba TV. My son can get sound from his XBox 360 on a different channel. I had the tv speakers turned off because I use an external set of speakers. I've tried several input settings on the DSS channel, but none pick up the sound and several say "no data." Thinking there is a problem with the receiver, I turned on the tv speakers, but there is no sound coming out of them. Could this be a problem with the TV sound transmission or both? Thanks in advance for your help! I'm at a loss to figure this out.

Sounds like a bad speaker. Do you have more than one speaker hooked up to a single output?

Nope - headphones do nothing to protect ears from loud noise. Actually they can make it worse as listening to loud music directly in the ears can be quite dangerous.

The Amplifier was failing and that's why you were getting the crackling noise.

Most receivers have an Auto Protect that shuts the system down and goes into Protect mode at the first signs of failure or overheating, usually indication by 'Protect' on the display.

I'm presuming from your post that you never got any indication that the unit was shutting down to protect itself and has just failed, so I'm presuming that this facility isn't fitted on this model.

Depending on you Technical ability it could be an easy repair (replacing the complete PCB or some PCB components). Your only other solution is a visit to a service engineer.

It is not so easy to probe into to find 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.In this case I think that some capacitors are faulty as when the set is put on it charges on to make the amplifier work. Possible fault in the protect circuit or preamp.
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.

hello ,i strongly suspect the units protect circuit is sensing a speaker problem.Listen to each speaker to see if all the drivers(woofer,midrange,tweeter) are working and if so are any of them sounding distorted.When an amp is damaged it wont play at all,sounds like a bad speaker to me.

well you have to Start "Toshiba Assist". The shortcut is placed on the desktop. Click on "Protect & Fix" and on the right side you should find button for "HDD Protection".

Does it display any message like "Protect" or something similar? Do you hear a relay click on then off?

Did the amp just not power up one day or did it stop working while you were listening to it? Finally, do you have teenage kids who might have been listening to your receiver and would have "neglected" to tell you that after listening to their music it suddenly stopped working?

It could be an internal fuse but chances are its something that requires a technician to repair (like the output transistors).

Have you tried the reset procedure I am outlining below at the end of this post?

If you have not done it exactly this way, try it. The "protect" that is displayed is the protection circuit being activated. Most times it is activated is to prevent further damage to the unit. Sometimes it can be activated from the unit being over-driven (played at very loud volume for prolonged periods or having the improper speakers or a bad speaker).

If this reset procedure does not work, you need to take it in for service preferably at a Marantz authorized service center because the problem you are having is not something that can be fixed by any sequence of keys being pressed. It normally happens when the unit has a blown channel. That is not the only reason, but it is the most common reason.

If you have the proper tools, a schematic, and knowledge of how to check electronic components to know when they are faulty, you can then fix it yourself. If you do not have these tools and the proper skills, you can cause much more damage to the unit than you started with, even to the point of starting a fire or making the unit un-fixable. This type of unit is not an easy one to repair, even for a well trained electronic technician. I work at an authorized Marantz service center and have repaired many of these and other receivers over the past 17 plus years.

Be aware, by using this procedure and then turing the unit on can sometimes cause more damage to the unit if it has a shorted channel or other problem that makes it draw a lot of current. This method is meant for qualified service technicians to perform after they have checked the output stages for any problems and the unit is still in the protect mode. You have been warned, so don't say I didn't tell you it should be taken to a service center first. If you see or smell any smoke or buring smell, unplug the unit immediately. You may want to have one hand on the plug when you do this, just in case.

Here is the proper reset procedure:

SR4500 Turn the unit on (standby without pressing the power button), press and hold the 7.1CH INPUT and ATT buttons simultaneously for3 seconds or more.

If you have found this free information helpful, a "FixYa!" rating would be appreciated, and if you need any more help I am happy to offer it, just ask!

Dave

p.s. I have told you all the warnings and suggested a service center because this is a very good receiver and I would hate to see it damaged more than it may possibly have already. It is possible that this reset procedure will return the unit to normal operation, but more often than not, the "protect" circuit activating means that you have a serious problem that can not be fixed by anybody without the proper training.

Check the speakers impedance. it should be greater then 6ohm otherwise you overload the system. Also, if the speaker sytem is rated (in Watts) below the amplifier's power it overloads the amp at higher volumes.

if your amp doesnt have air vent fins on the sides you shouldnt have any problems with overheating