[beat]

Hey all!
Havent been here for quite a while. Didnt realize how much I miss it! Anyhow, yeah.. I have this old marantz I was looking over for my friend. It had super scratchy pots so I got in there and cleaned them and all is well there.. However, after about a minute, one channel slowly fades out. I can twist push and jiggle everything and nothing changes. I have the lid off already so I looked around at all the components on the CB and nothing looks like its gotten hot or blew up. Its super clean. It is a Model 27 from 1970. Let me know if you can think of anything obvious I can look at. Thanks!
Beat

[thorman]

 I had a similar problem with a Sansui AU517 Intg/ Amp. It ended up being a Thermal Protection Shutdown due to a cracked ( or faulty ) solder .. This may or may not have anything to do with your situation, but what you describe is very similar to my issue...I also know that older Marantz gear had many owners losing one channel over time .......Good luck

[jules]

Slow, How slow? Has to be a hint in that.

Any other symptoms from that channel, like hum or buzz?

Any signs of domed capacitor tops or leakage from same?

As a precautionary move it's a good idea to replace the power supply caps. If they fail they can put a heavy load on components downstream.

Capacitors inevitably age and at 50 years old they've been around for a while.

I've got a Marantz 2285 sitting on my work bench right now.

[beat]

Nope. No hum or buzz. Just a slow fade. From a cold start up it sounds fine on both channels for about 30-45 seconds. I found another clue last night. The headphone output does the same thing. On this model, when you put the headphones in, it shuts off the speakers so aparently the two output stations are not totally isolated from each other. All the caps look perfect. I need to get some better clip leads today and I will check the DC bias at R547.

[jules]

How did you go with the testing?

[beat]

Thanks for checking in on me! I got busy with work and sidetracked with another project so I havent had time to test it more. I went ahead and cleaned all the pots and switches as recommended to me by someone and that didnt help. After I get it on the bench again, I will report back when I get a chance. Thanks!

[jules]

It might be worth posting on the Audiokarma, Marantz forum

https://audiokarma.org/forums/index.php?forums/marantz-audio.134/

They have a large number of very expert people with vast Marantz experience.