Onkyo THX SR 703 Receiver

[eeprof]

This unit is about 6 years old and its trouble dates back some 6-8 months. I do not have a schematic or service manual for it.
Upon initial cold startup: All channels (speakers) mildly motorboat followed by a decaying static which ceases in about 5 minutes. However, the audio remains somewhat distorted for about
10 minutes after which the unit operates normally. Trouble is independant of input or source and occurs through all 5 speaker loads.
My thoughts are something common to all amp channels especially electrolytic decoupling capacitors. This unit has always produced more than its share of heat so I know electrolytics would suffer somewhat. I know the 703 is similar to other Onkyos of that vintage so I am hoping someone out there has experienced this trouble with an Onkyo. I do not want to replace this receiver since it has phono inputs and analog tape input which is rare in todays market.
Thanks, Tom

 

[vtech]

I do have a service manual for several Onkyo's including yours. For over 25 years I was involved with consumer electronics and I seem to remember something about subwoofer/ channel noise that was known for those series. Not sure if it is even related to your issue? I think there was even a service bulletin that I probably have it on my archives.
I have since moved on from consumer electronics to Avionics field but still try to help out whenever possible. Service Man is about 10Meg PDF file.

 

[newbiesat]

Hello eeprof,
Following this link to download for yourself.
https://elektrotanya.com/onkyo_tx-sr703-e_sm.pdf/download.html