2275 Intermintant Left Channel

[gregmcm]

Posting this as it might help anyone with a similar problem.
- left channel cutting out randomly
- Deoxit switches no change
- clean speaker relay no change
- Deoxit switches again no change
- replace speaker relay no change
- total fluke touch one of the pre-amp jack wires and left channel returns fine
- investigate pre-amp jack and notice there is some sort of spring mechanism inside that engages when a jack is plugged in
- Deoxit the jack and use an RCA jack to work the mechanism by plugging the jack in and out 10 times
- once the pre-amp jack is cleaned and working all good!!

 

[Steven Tate]

Those contacts are in several later 70’s models and are prone to trouble after nearly 45 years. RCA jumpers are not a bad thing for these units.

 

[gregmcm]

Those contacts are in several later 70’s models and are prone to trouble after nearly 45 years. RCA jumpers are not a bad thing for these units.

Steve, I was aware that Marantz used the 2275 jumper set up in some of their units as opposed to the typical RCA jumper arrangement but what surprised me is the fact that these connections can cause the condition I encountered.

Following the troubleshooting path I was on, before I fluke discovered the connection issue, I was next going to dive into the left side amp board which as you know would have presented its own challenges and most likely resulted in a lot of work for no solution. Lets just say I'm happy that this fluke occurred.

 

[Steven Tate]

I had a similar problem on my 2325. Noisy channel on startup, and someone suggested Deoxit in and around the pre/main jacks to clean these contacts. It definitely seemed to help at first, but alas, the noise came back. Since it only lasts about 10 seconds on startup, I've elected to leave it alone unless it gets worse.

 

[wlhd1610]

Just a FYI....

Those Marantz rear panel internal switch main in jacks are known to be a pita even after a good cleaning.
Put in a pair of OEM Marantz jumpers or aftermarket 6" jumpers and be done with it and you'll never have to revisit that issue again.

Bob

 

[jerrycpor]

+1 ^^^^

@Steve regarding that hiss crackle at start up on your 2325. I just chased this same gremlin down for way too long on a 2325 that I completed a full resto on last week. In my case, I isolated it to the to the Tone Mode switch on the PE01 board. Despite a through cleaning on the first go around, it persisted, requiring a deep deep deep clean and lube. May or may not be the same problem, but try wiggling the Tone Mode switch on start up next time and see if what you hear changes at all.

Sorry to jump in, but the 2275 does have the Tone Mode switch too

Carry on...

 

[Steven Tate]

Thanks @jerrycpor! I'll do some fiddling with it next time I fire it up. It's always been amazing to me how quiet it gets after about 10 seconds - and it stays that way until the next cold start. It will be interesting to see if activity on the Tone Mode switch affects anything.