Marantz 2265B stereo issue on AUX input (Tape 1, 2 has no problem)

[YoungKim]

Hi guys, I've recently restored marantz 2265B.
Include
PE01(Pre amp section) - All of electrolytic capacitor and All TR (hfe matched)
P800 (Power supply section) - All of electrolytic capacitor, All TR, relay, and 3 dual diodes.
P700 (Main amp section) - All of electrolytic capacitor, All TR (hfe matched), Trimmer, some bias related resistors
Fuse change
Clean all switch and volume with Deoxit.

DC offset is between +0.1mv ~ -0.1mv, Bias is between 19.9mv ~ 20.0mv.
(It's like because of DVM error range)

Here is the problem.
When I listen music via Tape 1 (for Network play using Bluesound node 2i and V90 DAC) or Tape 2 (External phono amplifier) It seems right. No problem there.

But when I using AUX input for TV (using 3.5 socket on TV) left channel occasionally fails.
I can hear very tiny sound on left side when I turn volume to almost max.
After repeating turn on and off sometimes left channel turn back to normal but eventually it fails.
Just stop to sing suddenly. Regardless of speaker 1 and 2.
Sound signature is similar with when it has bad relay but I change a relay with new product from Omron.

At this moment If I push MONO switch, Left channel start to sing. But It's not stereo of course.
Also push Tape 1 or Tape 2 It turns OK without MONO switch is on.

Any advice?
I think there is some bad contact but don't know where to start and trouble shoot.

I already connect main in and pre out connector with RCA cable. It didn't help at all.

 

[Dingman]

Maybe a cracked solder joint from aux input to tone board. Maybe the pin joint is cracked.
When the left channel is dropped out, with the unit open, wiggle around those aux input wires.

Also, have you cleaned those mono\tape switches with deox or similar?

 

[YoungKim]

Maybe a cracked solder joint from aux input to tone board. Maybe the pin joint is cracked.
When the left channel is dropped out, with the unit open, wiggle around those aux input wires.

Also, have you cleaned those mono\tape switches with deox or similar?

Hi Dingman,
Yes I cleaned All switches except Tape Copy switches(Not using, hard to access).
Maybe because of the solder joints... I will check that first at pre-amp section.

Thank you for the opinion!

 

[rBuckner]

Tried a different connecting cable?

 

[YoungKim]

Tried a different connecting cable?

Hi rBuckner,
I've tried change AUX and Tape 1 (Source change) But It still happens only on the AUX input.
Maybe there is some solder joint or bad contact that I missed.