SMSL MINI5 Audio Amp Repair

[sean0118]

I recently repaired a 50W SMSL MINI5 Audio Amp. The symptoms were the speakers only emitting a strange static sound and the amp would start to heat up and smell burnt.

All four solder joints were broken on the header connector for the speakers. However, resoldering did not fix the amp.

It appears that a very corrosive epoxy had been used to glue down the inductors to the board! This stuff was so corrosive that it had started to eat into the copper of the PCB, making it flake off and expand, creating shorts in the output stage.

In the image below the corrosion has been scraped off the PCB where the top inductors were soldered (they were really bad) and then polished with Silvo. You can still see some corrosion on the bottom inductor footprints.

The copper under the top left inductor was still shorting out after I took this photo, so I used a knife and tweezers to widen the clearance gap. Under the copper PCB material had turned to a grey powder, nearly eaten through the board from heat etc. 







Anyway, this is just a heads up because it might be a common problem with this model? 


edit: forgot to mention, it works perfectly now the corrosion has been removed...