Marantz SR5007 popping on volume change and mute in Direct Mode

[BigOof]

Hi,

I bought a used Marantz SR5007 and it's giving me some issues that I can't seem to really place. It functions well in most settings, ARC mostly works, it has no issues driving my speakers in any of the digital input modes, but I'm having issues running analog inputs in direct or pure direct mode. For some reason in this mode there's distortion for every volume increment I give it, but once the volume is stable it has no issues. Muting creates a loud pop, switching to another source also causes a pop and so does turning off the amp in that mode. Again, no issue in the digital modes.

Initially I thought it was a relay, but now I'm not so sure. On page 140 of the service manual there's a schematic showing most of the relays, seems like Front Right and Front Left have another relay which I initially thought was for direct mode, but it seems like it's for the headphones instead. I don't think it's the speaker relays themselves but not sure what handles the input switching and muting here. I came across the R2A15218FP chip on page 186, which takes care of Analog to Digital conversion and volume attenuation. I'm wondering if it could be an issue with this IC? I have tools to work on it so I could replace it, but I'd rather not until I'm 100% sure that this is the issue. These chips do have a tendency to die and just kill Marantz and Denon receivers from what I've read. Not sure if it could be a cap or resistor that's just blown causing this issue.

Anyone have an idea what it could be? I've posted the link to the service manual below in case someone wants to use it as reference

Click here for the service manual

I came across this other thread with a very similar issue which was never solved:

https://www.badcaps.net/forum/troubl...-volume-change

Thanks!

Edit: Did a little more testing, when in Direct Mode it will not have this issue in the digital sources. Maybe it's some grounding issue on the analog inputs or a grounding issue between it and my mixer that I have connected to it? Looking at the schematics for the chip it seems like the mute pin is ground and connected to all inputs. The page I'm referencing is 144

[BigOof]

I've been doing some more digging and I believe the issue should be around the R2A15218FP chip. I came across another thread where the OP mentions clicks and mute not working properly and points to some pins on the chip not being soldered properly. You can find the thread here. I'll probably take the receiver apart these days and will check that chip for any desoldered pins.

[BigOof]

So I've done a little more testing and found something out. If my DJ mixer is on the crackling/popping happens on every line input it's connected to. With the mixer off I can change volume and mute without issues. When I have the cables plugged into the mixer and I touch both the metal on the cable and the chassis of the Marantz I get a tingling sensation/electric shock, it's more intense than any earth tingle I've had so far and can hurt. I'm wondering if there's a grounding issue somewhere? I've tried different RCA cables and the issue persists. Both the Marantz and my DJ mixer are not grounded (standard 2 pin plugs) and they're not plugged into the same sockets (too far away). My mixer is a Denon DN X-1500S and the power supply section does tend to get toasty. I'm wondering if a capacitor might be on its way out? I just measured the voltage between earth on the socket and the mixer ground and got 3mV, however, when I only measure the mixer ground and leave the other prong floating I get around 600mV-1.3V on the multimeter depending on which prong I use. Does this mean that there's voltage leak?

[BigOof]

Anyone? I've posted this issue on several forums without any reply. Used to be forums would be a nice place for technical questions and learning but it's so disheartening to see it and all its knowledge go away. Sorry for the rant, just feels a bit hopeless, especially when chatgpt can't be of any help either here.