Case 345560 . 12/23/2024. Poineer SX-880 . No sound. Unit in protection mode. Protection relay not clicking after turn on .
After troubleshooting found – only one channel causing this issue. ( DC offset voltage test on protection relay) . After we know what chanel is bad we focus on this specific channel. Found bad 2SA899 driver transistor( you can use 2sa939 , 2sa914) and bad soldering joints on board. After changing transistor , rebuild joints – still no sound. Investigating voltages on this transistor found resistor 330 ohm connected to base 2sa899 changed value to 10000 ohms. Same story in working channel – from 330 to 1500 ohms. Changing resistors in both channels solved the problem. Our guess – resistor change value problem developed by bad soldering joints on main board and hard working transistors in line after 46 years . Or they getting older like people do or something else on chemical level .
Nice receiver , easy to work on it , enormous power . All critical and major components designed on one board.
