I just had a Dayton 300-630 powered subwoofer develop the same problem. I sent mail to Parts Express, where I bought the unit, and they sent me the following information, which I haven't tried yet but will. I also saw the capacitor burn out and will have to replace it. -- Thanks for getting with us on our problem with the Dayton powered sub! We never did have a schematic for that amp, though most failures were the result of one c ommon problem. There are usually several darkened spots on the PC board, but usu ally only one burned part. If memory serves me, it is R3. Nonetheless, it is the tail current resistor for the differential input for the power module that was under-rated and burns up sooner or later. With the resistor open, the amplifier is more or less stuck in standby more. On most units, replacing this with a 1 wa tt, 22K resistor will get it working again.

R3 type in use is 22 K ohm and also use 100 K ohm ??? so wtf.. large scale? say`s service i ask it

Hello Mr Frank! I was serching on the internet for a datasheet and I saw your request. I have the same problem with R3 and C20, C21 and that the fuse is gone every time. My BD1 is burned. Unfurtnelly I have not foud any documentation about my Proson sub. But I will continue to serch. Perhaps you have found some thing? Kind regards Ulrik Straub Sweden kirlus@passagen.se ulrik.straub@bredband.net