We have a Onkyo TX-NR509 AV receiver at work. Apprently somebody was charging their phone from the USB port with a frayed USB cable. They dropped the cable and it shorted out on something metal. I guess there we sparks. Anyways, when you press the power button the front display lights up and you hear two "up" clicks (power relays?) one after another, a 3 second pause, a 3rd "up" click, a half-second pause, and finally a louder, kind of multi-faceted, "down" click that seems to be the powering-back-off. So I took it apart.
There is obvious burn around the USB port on the backside of the PCB. Seen best in photo #1-4 (4 is a closeup but with flash glare on the burn spot, 1,2,3 put the flash glare somewhere else) , the 4 solder points near the bottom between the two bigger ones are the 4 USB pins. Those 4 and all the stuff above that was burned. I tried to clean it up a little (before the pics) with some flux, but that also included scraping away burnt tiny pieces where you see L7504, L7503, L7502, L7501. Those kind of tiny components scare me. Those tiny ones are gone, what are they?. I don't care about the USB port, it can be removed or rendered useless or whatever, just want the receiver to work again.
Photo #7 shows the whole front board, where the USB and front controls are. I removed all the screws but can't seem to get the board off. It seems to still be attached to something by where the volume knob is connected (that area is seen in photo #6). Any ideas how to get this off? Desolder the volume knob? Maybe the knob comes off just by pulling straight out which reveals a screw or something else?
I found 3 fuses, they all look fine, not sure if there are any more.
The connections in photo #10 look sort of funny/orange-ish to me, but I'm not sure.
Would it be helpful to try and describe the general areas where I think the clicks are coming from? What should I check at this point? How would you go about diagnosing exactly whats wrong? Is there a schematic I should be looking up somewhere? If so where would be a good place to find it? Need any other pictures, or better pics? I have a multimeter and soldering iron and know how to use them (well...a little).
Thanks
There is obvious burn around the USB port on the backside of the PCB. Seen best in photo #1-4 (4 is a closeup but with flash glare on the burn spot, 1,2,3 put the flash glare somewhere else) , the 4 solder points near the bottom between the two bigger ones are the 4 USB pins. Those 4 and all the stuff above that was burned. I tried to clean it up a little (before the pics) with some flux, but that also included scraping away burnt tiny pieces where you see L7504, L7503, L7502, L7501. Those kind of tiny components scare me. Those tiny ones are gone, what are they?. I don't care about the USB port, it can be removed or rendered useless or whatever, just want the receiver to work again.
Photo #7 shows the whole front board, where the USB and front controls are. I removed all the screws but can't seem to get the board off. It seems to still be attached to something by where the volume knob is connected (that area is seen in photo #6). Any ideas how to get this off? Desolder the volume knob? Maybe the knob comes off just by pulling straight out which reveals a screw or something else?
I found 3 fuses, they all look fine, not sure if there are any more.
The connections in photo #10 look sort of funny/orange-ish to me, but I'm not sure.
Would it be helpful to try and describe the general areas where I think the clicks are coming from? What should I check at this point? How would you go about diagnosing exactly whats wrong? Is there a schematic I should be looking up somewhere? If so where would be a good place to find it? Need any other pictures, or better pics? I have a multimeter and soldering iron and know how to use them (well...a little).
Thanks
