Onkyo integra t-890 tuner amplifier

[Trainmaster]

Can anyone help? This is a strange problem.

My Onkyo Integra T-890 powers up fine, but when I push a "speaker selector button "A" or "B," the unit shuts down for a second, comes on again if the button is still pressed, and then repeats the shutting down.

It will stay on with no problem if the speaker buttons are not pressed. I even disconnected the speaker connections and tried it. The problem still existed.

Sometimes, when the unit has been on for a while, it will eventually work, sometimes not.

The headphone jack works fine.

Does anyone have a clue as to what the problem may be? I doubt if it is the power supply because they either work or not.

Any suggestions - I am desperate for help!

Trainmaster

[valveradio]

amplifiers can be weird things lol. it sounds like your output stage is ok. maybe the speaker switches need a clean or possibly they may have a dry joint on them assuming they are connected directly to the main p.c.b.
other than that it could be a bad connection somewhere and the act of pressing the speaker switch is flexing the pcb somehow.
whatever it is, doesnt sound serious.

regards, peter