Tascam M-320 noisy only after it warms up

Hi guys the headphone output on my Tascam 312 is borderline noisey. Direct outs are clean. I've changed power supply caps and bridge rectifier kbpc602 and w03, would those remaining diodes cause a 60htz hum as well? Warming up changes nothing. And even with volume way low I hear it. Turning up only seems to introduce an acceptable shushing sound. Any ideas would be appreciated.
 
Is the noise new? Or has it always been that way? The reason I ask is just about every vintage Tascam unit with a headphone amp in it is noisy in my opinion and one of the contributors is the opamp commonly used in their headphone amps in most of their vintage units, the LM386. So the noise is difficult to avoid...some of it has been there since new.
 
BUT...I just looked at the schematics and I remember now the M-300 mixers are different. The headphone amp on the M-300 mixers uses both sides of a 4560. And it's actually mounted on the power supply PCB.

When you say noise are you talking broadband noise or hum?
 
It's gotta be 60hrtz hum although I recently reflowed some solder joints and I made some big progress. Just got real lucky on that one. Only thing left now is a major ground loop. Ripping out the dimmer etc. Thanks for the reply I've read more then one of your posts and they've set me in the right direction.

Cheers
Eko
 
I've tracked down a major source of broadband/hum in my aux outputs. It would be nice to use them, is there a particular spot to start looking. It's almost like its a grounding issue? And to clarify I've tried this with nothing plugged in, which is quiet then added a cable to the aux output and the noise comes barrelling in. The other outputs are fine. Minus the effects send which is borderline good. It's a Tascam 312m.


Thnx
 
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Just did another test and found out aux2 is not bad when sent to my daw but aux1 gives off nothing of the signal I want to send. It just produces a broadband hush and a higher pitched hum maybe 120? It only changes from the aux send knob? No real noticeable change from the channel strip aux knob. Now I'm hurtin,,,lol
 
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Aux 2 works! I forgot to press the mic input, although when it was on line aux 2 worked and aux 1 was static, not sure about that, either or it's going nice now. Thanks Sweetbeats I fully understand that ignoramous comment now,,,lol
 
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