Case 453434. 02.03.2023 . Sansui 2000x receiver repair. Right channel is scratchy sound , thunderstorm sound on minimum volume level.
After applying heat and cold to all transistors in filter and driver sections found bad transistor 2sc458, position tr806, driver board f-1180.
Problem solved by replacement.
Pluses – simplicity, functions and boards separation ,easy to work on it.
Minuses – speaker plugs design on back panel (easy to break).
Works on maximum volume level only and no left channel.
Protection relay replacement solved problem.
Pluses – good attention to phono input. MC and MM phono inputs available.Good for phonograph players .Support MM and MC phonograph cartridges. Massive heat sink inside , good and stable sound.
Minuses – chaotic board management design inside, sandwich boards installation in central area with overheating on bottom board.
Case 4657687. 01/20/20223
Pioneer QX-9900 quad receiver.Distorted sound after 20 minutes.
Cleaning all front panel switches and control pots solved the problem.
Technical view feedback – nice unit , build to last long time , perfect modules separation for prive nting signal interference between modules, plus each section has own shield cover, multi-voltage transformer let you use this unit in any country around the world without modification , good quality components in use, good heat sink design, stable sound at any power level.
Minuses- hard to get to front panel switches and pots in case if they need replacement.