AU-717 Crackling noise

[Slaven]

Bought this amp used because my old one got thrown out by my mom if you can believe that. Amp works but there is crackling noise that comes in randomly after it warms up. When i got it first time one side wouldn't work 100% and its usually crackling with loud bass sounds. I tried different speakers and same problem. I used cheap contact cleaner and sprayed inside of the amp all over and i think it worked fine for few hours and it started happening again. Sound used to just come in and out randomly and crackling happens as well. I believe it was happening to both channels. Should i get a better spray for this and try again? It just sounds like a bad connection somewhere. I hope its not a failing part. Any suggestions would be appreciated.

Thank You

 

[Overundr1]

First suspect is the connected separated switch on the back, with amp off work it back and forth several times. Deoxit is your friend as far as cleaners go, not much else works as well other than full dis assembly.

 

[dr*audio]

In the first place you are not supposed to spray contact. Cleaner all over. You Inject it into any openings in the controls. Does it make noise with. no source connected?

 

[Robisme]

Six noisy transistors in the preamp.

Rob

 

[Hyperion]

Does 717 have a start or speaker relay?

One speaker relay and no 'soft start' relay.

 

[slimecity]

After checking the "connected/seperated" switch at the back, set this switch to "seperated", then test the preamp section by itself (by plugging the "pre out" terminals into another poweramp, then run a signal at low level straight into the "power amp in" rca terminals.

 

[Slaven]

Thanks for replies guys. So I think my switch in the back was at the wrong setting. I searched what each setting does and i pushed it back to connected or all the way to the left. I sprayed some more into the switch and slid it left and right few times and sound seems to be good for now. I will keep a close ear on any changes and if it goes back to crackling noise i will get deoxit spray.

 

[blhagstrom]

Six noisy transistors in the preamp.

Rob

And lots of old capacitors.
And the glue problem in the power supply.
And the fusistors.

When the AU-717 gets old, it gets cranky.

I have one that had that random noise.
I ended up changing every e-cap except the filters to fix it. It was the last cap way down in the bottom front board. I almost wore the screws out working on it. Now I won’t work on them unless it’s a complete rebuild.