The line fuse blows on power up. Input impeadance to the power transformre is 3 ohms. Is this correct? seems low.

If you keep blowing the 3 amp fuse it usually means you have a short somewhere in your low voltage control wiring or maybe within the wiring of your control box. I would ecommend using your ohm meter or continuity tester and start tracing each circuit unit you find where it is grounded at. It usually is in the thermostat wire where a rat or just an exposed piece of wire is touching metal somewhere. Just keep in mind that it could be a very small part of a wire touching the metal. Also check your low voltage wiring and make sure you have everything wired correctly if any of that has changed. At least you have a 3 amp fuse to blow instead of something else more costly to repair! Hope this helps.

your subs are the problem, not your amp, your wiring your subs paralelle, means dropping input ohmage, allowing your amp to over heat with minimal load, check the amp specs for running at low ohms, most hifonics amps are rated 2 ohms and higher, some however will run at 1 ohm, only on class b-a amps though.(competition) dropping ohmage will allow the amp to push more power to the voice coils, however the voice coils may not be rated for 1 ohm power, what ohmage are your coils rated at? do you have a min. of 100 amp inline fuse on your 1-0 awg wire? do you have internal fans? you can add mosfets to the amp but if you do so, you'll have to re-program your amps mother board.

Fuse blowing is due to excessive current drain and the the first clue is the blown fuse itself. If the fuse blows with a flash a bang and splatters copper across the inside of the glass you have a hard blow caused by a dead short on the power supply, check for power switch flashing over internaly. Short circuit main filter capacitors. Shorted turns in power transformer primary winding. If fuse just separates check for short on output transistors C to E. Try isolating fault by disconnecting LT pos/neg supplies to output stage. Also check for partial shorts on speakers and speaker wires using an analog ohm meter on low ohms setting.

The fuse blows because of a short in the Power Supply. The power transformers primary windings are probably shorted. next in the chain would be a bridge rectifier or a quad of diodes forming a bridge rectifier with a couple surge diodes off of the filter caps. so if you can disconnect the power from the amp, on the power tranny disconnect the primary wires ( the input AC power wires) usually white and black and take an OHM reading with a mulimeter accross the white and black wires. you should get a reading of 15 ohms or higher up to 30 or so. if so the primary windings are good. so then check the secondary (output windings) red and red yellow, etc. ohm reading and you should get a relatively low ohm reading 2-6 approx. if so its a good tranny. on the primary side if you get a real low reading for ohms , like 1 or something, its toast. once you rule out the tranny, switch your digital mulitmeter to read diodes (in the ohms area looks like a diode symbol (a line and a solid triangle with the line being at the tip end of the triangle). desolder one leg of the diode and put one probe on one side and the other probe on the other side. it should only ring out in one direction. you will be testing approx 6 diodes in this power grid on the pcb. you can also desolder the filter caps after you safely discharge the voltage with a 1 ohm 1 watt resistor to ground and use an analog volage meter to see the needle rise in one direction and not in the other (switching the test probes from one side to the other on the cap). usually what i do is just spend 20 bucks on all those parts from mouser.com and instead of desoldering to test i desolder to replace with new. diodes usually part number 1N4003 or 1N4004 somewhere in that ballbark. hope that helps. i think its your power tranny primary winding that is shorted, be aware that this might domino effect into the rectifier and caps, so expect to replace them. its super easy!! you can email me from my website yostamplifier.com

Line level is known as 600 ohm line signal where the output impedance is 600 ohms and the input impedence is between 10,000 to ~ 50,000 ohms. There are normally no issues when connecting line level to line level. It is meant for transferring signal, not power.

Even though I don't have a schematic, if you have a VOM, (Volt-Ohm, Milli-Ammeter) we can start. Just because tubes are old doesn't mean they are used up. If a tube doesn't light up that would be a bad one, but they are in parallel off a winding of the power transformer. 1.) Check the on/off switch with the ohmmeter and the line cord for conductivity. 2.) Check the primary winding of the transformer for a low ohms reading. (less than ten ohms). 3.) Some where between the power switch and the pwr. trans. should be a fuse. After these three you should be able to put 120vac. to the unit and bring it back on. Get back with us, Dale

Goo day sir, the T on the fuse has nothing to do on you marantz fuse blowing up, chances are you amplifier is shorted, check you IC amplifier/power transistor for shorts. Check also your speaker impedance. usually they are 8 ohms. You can use a technician's multitester device to check the impeadance. An imbalance or mismatch speaker can cause a fuse to blow and destroy your amplifier. hope this helps.

It sounds like you have a bad speaker on the zone 2, or you have the speakers connected improperly.

When you engage the zone 2 a relay clicks and the speakers then become part of the amplifiers circuit.

If the problem was in the amplifier, it would go into protect mode without even having speakers connected to it.

If the speakers all check good, you most likely have the wrong type of speakers, meaning the impeadance is too low, or you have too many speakers connected to it.

On the back of the Denon, you will see right around the speaker output jacks, what ratings the speakers should be. If I remember correctly, it says 6 ohms or more when using only "A" or "B", and it says 12ohms or more for "A" + "B".

If you have two 8 ohm speakers on the same speaker jack you now have a 4 ohm load. That is below the ratings and can cause the amp to shut down (go into protect). Since your amp shuts down right away, I think you have a bad speaker or way too many speakers connected.

I have seen many times when people will connect 2 or 4 speakers to the one of the outputs that are designed for only 1 speakers.

If you are using too many speakers you will need a speaker distribution box. It has a resistor network built into it so the amp never sees a lower impeadance than what it is designed for.
You can connect 4, 6 or 8 speakers to one set of outputs designed for 2 speakers. You do loose a lot of power to the speakers, but it is better than blowing up your amplifier.

If I can be of any further help, let me know.

These JBL speakers are not made for a home stereo reciever. It could be part of the problem.

I do know that they have a high frequency input and a full range input on each speaker.

I am going to guess that maybe you have them connected to the high frequency input.

Are you using 1/4 inch jacks connecting to the input of the speakers?

I don't remember these speakers having a input for wires.

You may have another issue using these speakers with that reciever.

The JBL speakers are 4 ohms each, it is very likely that the onkyo requires 8 ohm speakers.

Look on the back of the Onkyo where the speaker jacks are at and see if it says anything about the minimum impeadance.

The impeadance is the ohms. Most home recievers are not designed for anything less than 8 ohms. Some are, but most are not.

Using 4 ohm speakers on a system that requires 8 ohm speakers can cause damage to the reciever. Mostly at higher volume levels, it will cause the reciever to overheat and shut off, maybe short out a channel. It pulls 2 times the amount of current thru the output transistors as 8 ohm speakers.

Let me know if this helps you or if you need more help.

When the protect mode is activated,always be the audio amplifiers IC's damaged you gotta change them.