Pioneer SP-SB23W Repair
Unable to find any service info or schematic I spent several days troubleshooting this sound bar and thought I should share my findings. If anyone has a schematic or a link it would be greatly appreciated.
Pioneer SP-SB23W Sound Bar User Manual
The symptom, as many I have seen posted, was a failure to start up. The sound bar would come to life after repeated pressing of the power button, sometimes as many as 20 presses.
Upon first inspection after removing the power-supply/amplifier combination I found one of the capacitors on the amplifier board closest to the heat sink swollen. (C618). I really thought this was my lucky day. The capacitor turned out to be quite leaky and only measured about 800 uf and was supposed to be 4700 uf. I suspect that these two capacitors are part of the amplifier supply splitting circuit. It appeared the power supply was putting out 36 volts and the amplifier was operating on a split +/- 18v supply. After replacing this one the same symptom remained.
My next suspicion of course was the powersupply. From what I can tell it delivers 36 volts and a standby voltage of about 7 volts. Both of these voltages appeared stable. I removed both capacitors (470 uf and 47 uf) and found they both tested ok and had normal leakage when subjected to their rated voltage.
At that point my attention turned to the amplifier board and I began removing and testing capacitors. First was C604 (can’t remember the value off hand, possibly 2200 uf) It tested ok but when subjected to its rated voltage of 16 volts it was on the leaky side. I replaced it anyway with a quality Nichicon capacitor. I reassembled everything and the problem was still there.
Next were the four 47uf @ 50v capacitors on the amplifier board. I tested them all and three of the 4 showed damaged or unknown on my tester. I replaced all 4. After reassembly, still no luck.
Next I checked the input board. It has just 3 capacitors on it. Two are 47uf @ 10v and one 100uf cap. These were all good.
At this point I was ready to give up. I really felt it wasn’t capacitor related. Just for sport I dragged out my oscilloscope and probed the 36 volt supply and the 7 volt standby supply. The 36 volt supply looked rock solid with some expected switching pulses. (25 kHz) But much to my surprise the standby supply was jumping up and down a bit. I attached a 47 uf capacitor across the standby supply and Ureka! The unit powered up with every power on cycle. I thought I would just leave it at this point now that it was working but my conscience said, fix it properly. Once I changed the 47uf cap on the power supply board all was good!
Bottom line is that Pioneer either cheaped out or got a bad batch of 47uf cpaacitors. If you’re repairing on of these units replace all 5 of the 47uf @ 50v capacitors. This should solve your problems.