First job: what looks like an ELEX (Edifier) C3100 speaker with mains hum from one speaker, which means a shorted amp chip, so straight in; going by experience the middle amp chip is the problem; swap it (2032) and the hum is gone; pull the two originals, BDI, imported; thermal paste on, fit the amp chips and touch up the solder; power up and test, big brand at a low price, no buzzing; input signal, left and right channels OK, sound from both sides, rich deep bass, play a post-80s DJ favourite. Second job, a Chinese-classics story player with a broken USB port, replace it; charging current 0.7A, 3.8W; the cell has been starved flat, it must not drop below 3V, 30A power cell discharging at 3.8(V); ‘Welcome’; full charge 2.6 (reading), enough to beat Dahuanma (joke), all good. Third job, a Midea handheld vacuum, battery replaced (no commentary), powered up and tested, perfectly fixed, put on charge. Comments: Edifier speaker (creator: yes); swapped mine for an LM1875T, the TDA2030 is retired; which one is the voltage-select wire; assorted repair requests (water dispenser, freezer, range hood); he has every part going.