No sound from left channel?

[Oski1928]

I have a Marantz PM KI Ruby. When I listen to music I often engage a +1db increase in the bass region using the tone controls. Tonight I sat down to listen to some music and noticed there was only audio coming out of the right speaker. I had just been watching TV through the system without this issue and the only thing I changed when switching to music was turning on the tone controls. I turned them off and both channels were now on again. Any idea what the problem could be here?

 

[Chrispy]

A glitch in the system? Try running a reset if it has one....I'd do a soft reset at first (just unplugging it from power for a bit) rather than a full reset (if it has one).

 

[DVDdoug]

Is it repeatable? If not, it was probably a coincidence and you've possibly got a bad connection somewhere (possibly inside the amplifier).

 

[Oski1928]

A glitch in the system? Try running a reset if it has one....I'd do a soft reset at first (just unplugging it from power for a bit) rather than a full reset (if it has one).

I powered off the unit fully, though I didn’t unplug it so worth a shot. When u turn it off with the remote it goes into standby, but when you push the power button on the amp the whole thing shuts off and that’s what I did.

Edit. Just shut down and unplugged. Still no fix.

 

[Oski1928]

Is it repeatable? If not, it was probably a coincidence and you've possibly got a bad connection somewhere (possibly inside the amplifier).

Yea, sitting here right now if I turn on tone controls I lose the left channel.

 

[Chrispy]

I powered off the unit fully, though I didn’t unplug it so worth a shot. When u turn it off with the remote it goes into standby, but when you push the power button on the amp the whole thing shuts off and that’s what I did.

Edit. Just shut down and unplugged. Still no fix.

Many units with power off are still in standby, so better to unplug. It doesn't always help nor are full system resets available generally on gear like yours (now that I've looked at details). Maybe a bad solder joint? Something else failing? Hard to know.

 

[Oski1928]

Many units with power off are still in standby, so better to unplug. It doesn't always help nor are full system resets available generally on gear like yours (now that I've looked at details). Maybe a bad solder joint? Something else failing? Hard to know.

I edited my response to say I unplugged it and it’s still not working.

 

[Zek]

only thing I changed when switching to music was turning on the tone controls. I turned them off and both channels were now on again.

There is something in that switch, it is either dirty or defective.

 

[Oski1928]

There is something in that switch, it is either dirty or defective.

That would make sense to me if that was the case. Obviously I don’t expect you to be familiar with my specific equipment, but do you have even a small idea of what kind of job this is in terms of if it’s something I may be able to take care of myself? I’d like to avoid having to send the unit away for several weeks to be repaired

 

[kemmler3D]

I had (have) something similar in an amp where it would power on fine but if it was disconnected from mains for a long time, it would take 20+ minutes to come on. Apparently a capacitor went bad somewhere... could be there's a real issue in there.

 

[Zek]

but do you have even a small idea of what kind of job this is in terms of if it’s something I may be able to take care of myself?

In the picture I don't see any physical switch to turn on the tone controls. Is it done via the remote control or the left button?
You need to find the service manual for the amplifier and see how it is solved and how you can access the inside of the amplifier where that switch is.
To clean the switch, you should use a cleaner (they say it's the best cleaner for brakes) - never use WD-40, it only greases the contacts even more.

 

[DVDdoug]

There is something in that switch, it is either dirty or defective.

Maybe there is a tone control "bypass" relay that's defective.

...It is an odd problem for "pure electronics" or software if there is not a switch or relay or something mechanical.

 

[Oski1928]

In the picture I don't see any physical switch to turn on the tone controls. Is it done via the remote control or the left button?
You need to find the service manual for the amplifier and see how it is solved and how you can access the inside of the amplifier where that switch is.
To clean the switch, you should use a cleaner (they say it's the best cleaner for brakes) - never use WD-40, it only greases the contacts even more.
View attachment 389554

The only way to engage tone controls is via the remote. I’ll have to take a look to see if I can find a service manual. Thanks for the tip of WD-40

Edit: I just found a service manual online, and I have no idea what to make of it. I’ve never worked on or opened up a component like this before.

 

[Zek]

The only way to engage tone controls is via the remote.

I then assume that there is no physical switch, but that this function is performed by some electronic circuit, which then rejects everything I wrote previously.