[Help]Amp tripping into "Protection Mode" (1 Viewer)

I have a Yamaha HTR-5560 AV Receiver and for some reason it goes into "Protection Mode" (Turns itself off) for no apparent reason. This started about 3 weeks ago. Last week I took it in to be reapired at Tweeter (where I bought it)

I received it back from the repair yesterday. The following was in the comments on repair slip:

Diassembled Unit to locate fault
Repaired weakened solder joints and connections
***Caution***
This type of failure usually occurs due to shorted speakers or speaker wires. Please have your speakers and wires checked by a technician. Failure to remedy will cause unit to fail again.

Well, on Saturday of this past weekend, I replaced "every" wire that connects to the receiver. From speaker wires to component interconnects. I purchased banana plugs to connect the speakers to the unit. The speakers haven't changed in 4 months. The are all the same brand (JBL) and model (HLS), and all 8 ohms. This shouldn't have happened again, and last night after connecting everything back up, it did it again in under 10 minutes of use.

The unit worked flawlessly for 5 months, and I can't for the life of me figure out what the problem is now.

How do you check if a speaker is shorted? I know it is not the wires. I highly doubt it is the speakers... but I want to make sure.

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Click to expand...

I had a similar problem with my Yamaha RX-V595. The unit would shut down for no reason. It got to the point that it wouldn't even turn on anymore. I had the unit checked out and the problem was a defective relay switch attached to the switched outlet in the rear of the unit. The relay switch contacts were "fused". Once the switch was replaced, the unit worked fine.

You could take a basic multimeter and measure the impedence across each of your speakers, or alternatively use the conductivity beep setting which beeps when things are common (aka, shorted). Disconnect the wires from your speakers first and then measure just as simply as measuring across any other resistor (ie, put the hot to the hot post and ground to the ground post, for DC circuits this choice shouldn't even matter). To make sure you are using the conductivity setting correctly just touch the 2 leads of your meter together and if you hear the beep, then its working. Put one to each post again and no beep means no short for the DC current to run across.

If you are seeing 6 to 8 ohms and not getting any connectivity reading then I doubt its your speakers. I'm not sure about the AC impedence characteristics of speakers, but I'm almost certain that such an odd thing would not be the cause of this power fault (to high frequences a capacitor is a short and your multimeter will not be testing with very high frequencies but instead using DC).

I would be espeically leary of blaming anything else in the system, although another good testing step would be to run the system with one speaker removed at a time. That would at least narrow it to one pair of output/speaker. Then to figure out which was the culprit you would just hook the "faulty" output up to one of the other now known good speakers. If it then fails you have some bad internals, if your system works fine then you've found your bad speaker.

Realize of course that testing will take some time like this (give it 15 minutes per missing speaker), but it is free to try at least. You could just enjoy some music while you do this and go on to other things waiting for the system to crash.


And yes, normally if you get that message it is because somewhere in the path your hot is dropping straight to ground allowing an unlimited flow of current down that path and back to the receiver...ie, not good. I haven't ripped one apart, but we can assume that you have whatever detection circuitry there to shut things down on this fault. If that detection circuitry itself was going bad then you would be getting false shutdowns. That sounds like a possibility to me.