Denon S301 Malfunction

Thread Starter


Joined Jan 14, 2018
Hi there !

I have a Denon S-301 that has stopped working , when pressing the on/off button, the blue led light around the button starts flashing repeatedly and nothing works. Suspecting one of the several power outages in my area during windy weather to have something to do with all this.

I have read on this issue and checked my two speakers and subwoofer internal resistance, no short circuit.
-Tried performing the ''hard reset'' and issue persists.
-Decided to carefully open the device to look for anything obvious , i.e. : burnt fuse, visual defect on PCB... etc... none was found.

I am an automotive technician with decent understanding of electronics, but yet not a lot of experience.
I would really like to find a way to diagnose/fix my Denon unit(and learn at the same time ;) ! )because it is immaculate and i don't wanna trash it.
-I started checking how everything is supplied through the voltage transformers , supply to the 2 125v fuses, etc.
-I heard of possible ''output transistor'' failures, and i have found one of 2 fuses not being supplied, suspecting a specific transistor base not being triggered on one the Subwoofer unit PCB, where the supply units are.

Would anyone be kind enough to help me find a solution for this problem , or maybe have access to Denon Wiring schematics
for this specific unit ??

Thanks in advance,
Kind regards,

Thread Starter


Joined Jan 14, 2018
Hi there,

thank you very much !! I have all what we need , please see the link below !

please have a look at page 201 of the manual where the main supply board layout is.

yesterday i started brainstorming on it, today i will reassemble to a minimum that i can test it live.
-i have visually checked for any visual abnormalities( capacitor bulge, fuses, etc) , all seems ok.
-from what i remember, Fuse 902(2a/125v). is not supplied with any power.

see the pics i have attached for more details of ''my findings'' !
Let me know you thoughts on this,
many thanks,