[Help] [2235b] right channel dies out intermittently

[Ben1224]

I have 2 marantz 2235b systems that both do the same.

The issue: the right channel on the main, backup/remote and headphones stops working after about 10 minutes (sometimes longer). If I turn the volume very high, the right speaker crackles and then starts working again.

I have noticed occasionally that the sound in the right speaker fades out slowly.

I should note, the right speaker isn't completely void of sound. It is just very low, nearly silent.

With that stuff being said: the relay on the power board works properly..it looks like if it was the relay, both speakers would die.

From my experience with electronic devices, it seems like possibly a capacitor failing open or resistor that heats up causing resistance to increase. That leaves a lot of options..Could be wrong, I have a cheap multimeter but no scope for testing.

I'm typically alright when it comes to fixing circuit boards and broken electronics. But this system is large and has wires everywhere.. I don't want to take it completely apart and find out the issue was something easily accessible.

Any help would be appreciated. Thanks!

 

[AE Bob]

What you are describing is similar to the typical symptom of bad contacts on the protection relay. The relay cover can be removed, and the contacts burnished (with a small strip of 1200 -1400 grit emery folded to make it double sided), then cleaned with a good contact cleaner / lube..

A similar symptom can also be caused by poor contacts in the switches in the Pre / Main jacks (only in the main in jacks on the 2235B). You can just bypass them with a patch cord as a test, and if that clears the issue, you can clean them by spraying some contact cleaner / lube into the jacks and inserting an RCA plug several times (to open and close the switches).