Wharfedale RS10 subwoofer is restarting at higher volume

[drakejest]

So i have a Wharfedale RS10 5 in 1 taken out from storage (for about a year). The subwoofer has been misbehaving lately. So the subwoofer is an active subwoofer that needs to be connected to the wall and takes in a subwoofer signal from an amp.

So at 50 (out of 99) volume, i could not feel the subwoofer, very quiet it might as well been off. At 75 volume is where i like it, the base is strong, but here comes the problem. With songs that have a lot of base in them, after a while the display will start to flicker (the base is still there) like its not provided enough power. At 85 volume is a bit more crazier, again the base feels strong and when the heavy continuous base of the song comes the subwoofer flat out shutdowns and restart. It will not play anymore, unless it is restarted by turning off the wall power switch and turning it on again.

Given that i suspect a blown capacitor or the transistors are failing. It also does not sound like a blown speaker though it can kick, but not for long, like its not being fed with enough power. That is just my opinion though. I would like to attempt to repair it, i have experience in electronics and comfortable soldering/de-soldering stuff, but this will be my first time repairing audio electronics. Glancing at the circuit there doesn't seem to have a component that catastrophically failed.

Has anybody experienced this before? What could it possibly be? Before i begin dismantling the stuff i would to hear your guys opinion first

 

[AnalogSteph]

How warm does the heatsink at the back of the unit get? Do you have any means of measuring mains power consumption?

The symptoms observed would seem to indicate a very unhappy sub power supply (seemingly the linear, transformer-based kind) and amplifier. You seem to be pushing it to the point where protection kicks in.

Barring a bad connection between the mains and transformer primary or a bad power switch, there's relatively few things it could be:
1. You may be asking too much of the sub to begin with. Setting subwoofer level by feel isn't exactly the definition of a precision measurement, you know.
2. The subwoofer driver's voice coil may be cooked, with shorted turns as a result of overheating, reducing output substantially. Measure the resistance across its terminals and compare it to the rating generally printed on the back of the magnet. It should be roughly 80% of that. A substantially lower value may indicate shorted turns. Does the cone move freely when pushed in?
3. The sub enclosure may be leaky, reducing its acoustic output level.

Posting a few pictures of the innards may not hurt, as this system appears to be somewhat uncommon.