Customer asked if could take a look at this speaker to see if it could be fixed. Why not?!
Powered up and all seemed ok for a minute or so, but then as warmed up, could hear some very odd distortion occurring under load.
Inside we have a module, which was getting very hot. This module has a £200 replacement price tag (whyyyyyyyyyyyy!) the whole speaker is only £279. Nuts! We can do better.
Further inside we have a metal shielded module case, removing the cover:
And inside there we have the heart of the system a small Class D setup:
And far too much heatsink transfer compound:
We have a TDA8950TH all in one Class D amp chip, which I suspected was faulty so a replacement was sourced:
Only a smaller smearing of compound needed (only needed to bridge any slight differences between the two metal surfaces) – too much can actually hinder thermal transfer!
And refitted the module to the main board:
Now distortion was gone, but was still getting far too hot for my liking and homed into one of the inductors (over 70C):
Unfortunately I didn’t get a photo of the issue but what had happened is that the inside former (around which the coil is wrapped) had slid out of the coil as there was space between the outer housing and the pcb, and this reduced the inductance significantly and probably increasing AC core loss, causing very rapid heat buildup. I was unable to source replacement 22uH inductors good for 7.5A for at least a few days so set about rewinding from some recovered 1mm copper wire from an old ATX power supply toroid!
Used Acrylic Protective Lacquer (good to 125C) to secure in place and squeezed in the former until the required inductance was achieved, and left to cure.
After this, replaced in the main board (with spacer filling material under both inductors to stop the same thing happening) and was now operating about 50C but given was in a case with no airflow, we could improve on that! Had some small and relatively quiet 40mm fans in stock and was just enough room to engineer and attach to the module heatsink:
After this we have a long-lasting solution and this monitor can go back into service for many more years to come!