marantz 2215b phono stage... i think

[tonymaine]

So my 2215b has started acting up only on phono stage. Confirmed with multiple turntables and speaker combinations and No problem on Aux or FM or AM.
The problem: low rumble (think of a cat purring with speed as if you were drumming your fingers on a desk at 4 beats per second roughly, but will sometimes speed up cadence a bit). This is on all volumes when on phono when arm is cued up and not playing (I am sure it is doing it when playing record, but music hides it). It really isn't that loud, but I am sure it is impacting the sound overall.
I am assuming I have transistor issues on phone stage. Before I order up the parts and break out the flux and iron, does anyone think anything different?

Also, if you have a phone stage rebuild bill of materials that you can point me to that would be great or I can just assemble from the service manual.

 

[Steven Tate]

The 2215b Phono stage doesn’t have any discreet transistors. It has a couple of integrated circuit op amps. Is your turntable grounded to the chassis? Otherwise, maybe an internal grounding issue or bad cap.

 

[bktheking]

I'd start of with a recap of the p400 board like Tate says.

 

[tonymaine]

Thanks for quick reply. yes TT is grounded, and problem happened with multiples. I can try to see if internal ground issue. If not capping the P400 sounds like next step. Will post update.

 

[tonymaine]

BTW: Any parts list I can copy from for this? Thanks

 

[Steven Tate]

Looks like only eight electrolytic caps on that board. Their values are listed in the service manual. I would replace anything 3.3 uF or less with WIMA MKS2 film caps.

 

[tonymaine]

Sorry now I feel really stupid but not afraid to admit it. I took out the marantz and put in my HK330c figuring I would be working on the Marantz. Lo and behold same sound with the HK!!
So I found the culprit is actually a chrome cast we have in the room. Even though it was plugged into an outlet six feet socially distant from the receivers and and in no way wired to them, when I unplugged the chrome cast brick power. It all went away.
Would never figure something that far away could have an impact.
Oh well, I saved the seven bucks in caps and solder

 

[bktheking]

I once had to take an amp out of a guys house who called me over to repair it, big monster of an amp- the hum he heard ended up being the power conditioner he had the amp connected to. I got it home, plugged it in and it was silent. Brought it back to the guy, tried it without the PC and no hum. Didn't charge the guy, have a nice day.