BNS Intelligent SDS-Sub MKll schematic wanted

[JohanH]

BNS Intelligent SDS-Sub MKll schematic wanted for repair

Hello all,

I bought a defective BNS Intelligent SDS-Sub MKll.
It's an active subwoofer
Haven't received it yet so hopefully just a blown fuse 😉

There doesn't seem to be much info available on the later BNS speakers so I'm asking here for info and hopefully a schematic of this subwoofer.

Thanks in advance,
Johan

 

[JohanH]

It arrived today.

Unfortunately the fuse is ok.

There's a fairly loud hum when the sub is switched on, the on LED lights shortly and then goes dark again.
So good thing the amp seems to be working.

There are 2 PCBs inside: one amp (TDA7294) with rectifier and caps and one with crossover, standby circuits and inputs (3 quad opamps TL084 and a SA572 compandor). Not sure what a compandor does in a sub....

I resoldered some suspicious joints and tapped the PCBs to sort of check for loose joints. There is + and - 37V across the PS caps.

Next I will try so see if amp and crossover function seperately.
And take some pics.

The components inside surprised me somewhat; metalfilm and 1% resistors so hopefully I will be able to resurrect the thing.

Cheers,
Johan

 

[JohanH]

Speaker is Peerless 850384
PCBs are marked UnisubAmp and UnisubF2

 

[JohanH]

Finally got around to working some more on this.
Ended up replacing the TDA7294.
Sound distorts occasionally and hardly works when using the high power inputs. RCA works better; but still distortion.
So back to the workbench for more detective work...

 

[JohanH]

And finally succes.
Distortion was caused by a bad connection at the speaker..

 

[rafaeldatarock]

Great to see you managed to fix it! It's a great sub, i've been using it for years.
I still don't know what the ACC switch is for though, all it seems to do is make the volume way louder.

Does anybody know what the 'ACC' switch was originally meant for?