Any idea whats wrong with my amp?

[vaio-fx]

I have this really old Denon PMA 520, it had been left under my bed for a while and was fine the last time I used it months ago. Now ever since I got it back out (this is over the space of a few weeks), it keeps cutting off and then turns back on instantly. Basically the power button is one of those push in buttons, that once the amp is on stays in unless you press it again to turn it off. When you turn it on, it by default goes to the "Tuner" channel, I then select "AUX 1" for my PC but then it switches back to tuner by itself, I'll then press AUX 1 and it switches again soon later, this is an endless cycle, sometimes it takes a while, sometimes it does it all the time. I'm pretty sure its actually turning off and back on again instanly rather than switching channels. My friend came over the other day and had a look inside it, there was nothing obviously wrong, it wasnt full of dust and the fuse hasnt blown. Any ideas? Thanks.

EDIT: also, if you keep pressing AUX 1 every time it cuts off, if you do it enough times the amp usually then stays on normally.

 

[clacker]

I have this really old Denon PMA 520, it had been left under my bed for a while and was fine the last time I used it months ago. Now ever since I got it back out (this is over the space of a few weeks), it keeps cutting off and then turns back on instantly. Basically the power button is one of those push in buttons, that once the amp is on stays in unless you press it again to turn it off. When you turn it on, it by default goes to the "Tuner" channel, I then select "AUX 1" for my PC but then it switches back to tuner by itself, I'll then press AUX 1 and it switches again soon later, this is an endless cycle, sometimes it takes a while, sometimes it does it all the time. I'm pretty sure its actually turning off and back on again instanly rather than switching channels. My friend came over the other day and had a look inside it, there was nothing obviously wrong, it wasnt full of dust and the fuse hasnt blown. Any ideas? Thanks.

EDIT: also, if you keep pressing AUX 1 every time it cuts off, if you do it enough times the amp usually then stays on normally.

Is this a guitar amp?

 

[detox1]

my amp does something similar, as in after i turn the power on it takes about 30 seconds for the relay to kick in.
even thou the lights come on, the amp itself is still off. but it only does it when its cold, i can turn the power off and on after that.
but as soon as it gets cold I have to wait. I have an old TEAC amp. its about 20-25 years old. but still pushes old some serious power.

I would assume yours is doing something similar, sticky relay probably.

 

[praer4life]

you have an electronic fault -a short most likely as for person 2 its most likely the capacitors or resisters going replace them and watch the sound

god bless u in jesus name raju