Help me fix my subwoofer! Fuse keeps blowing - Tannoy TS12

[boxrick]

Hello all, I have a subwoofer I have owned for many years I do not wish to replace. It has just started blowing fuses and instantly blows them upon replacement.

I am hoping someone may be able to point out anything obvious which may be wrong, or things I can test or look at with a multimeter?

I took the subwoofer apart and I have also included a video to add more angles.

( Still processing at this time so only showing 1080p and not the 4k upload )
Can anyone help out?

 

[Martaine2005]

You would have to check mains input first.
Bridge rectifier would be first on my list.

 

[kellys_eye]

Disconnect the power supply DC output and retest with another fuse. If the fuse blows the PSU is faulty. If the fuse doesn't blow then the amplifier output stage is faulty.

 

[danadak]

5'th picture own, middle of board, is that power R burnt ? The R right next to white molex power connector.

Caps usually principle concern. Look for parts with bulging tops (the small electrolytics) :



Any heat discoloration on any part or the PCB, thats a sign of localized failure or
a circuit that is driving a higher power portion of circuit into high power.....

Can you get a schematic for it ? To do some testing.

Look at PN junctions with a meter on diode Test scale, and bipolar transistor junctions.
Fwd biased they should read in range .5 to 1 V, rev biased 10's of K or larger. Diode test scale
is meter selected in ohmmeter and there usually is a diode symbol next to it.


Regards, Dana.