I have just joined ecoustics today, but I am doing hobby repairs since around 15 years.
I have above mentioned acousticmas system bought secondhanded and now it has a crazy issue, which I am trying to fix since last 2 weeks.
It went dead as I had it transported interstate. When I opened it I could see sparkings inside because of the securing glue going black and becoming conductive.
I removed the glue which was a big job lasted for around 2 days as I had to remove every component and put it back again. Even after doing this no change to the dead state.
After digging more I found that the glue actually penetrated through the board and has made the board conductive on the affected part. Also, some of the components also got faulty such as polyester capacitors as the thing penetrated through it as well.
Fortunately, it was around only 1 mm deep.
So, I had to do a big and lengthy job of actually removing every component again and then srapping off the afftected part of the PCB as well as enlarging the PCB holes for getting reed of the affected part using my motorized wood carving drill.
Believe me it's a hell lot of a job as I had to check each and every component before soldering it back on. Also, needed to take photographs so as to avoid replacing part with wrong pins.
Even after doing this I could not get the system to work and also the subwoofer started making extremely loud thumbing noise like a harley davidson. after some time I could see that it actually burned the fusible registers on the subwoofer ampwhich drives the driver transistors from the op amp. Luckily I could get the burnt register values (130 ohms) from the photographs.
i have replaced the registers without any change in state of the amp.
Now, I could detect following 2 conditions:
The relay does notswitch off even I take of the serial input pin from the bose cd player (it has basically no dependance on the state of the serial input.
Second major thing is if I remove the opamp from subwoofer driver stage (LF411CN) then the subwoofer amp gets disconnected from the circuit and the satellites works without any issue. The system basically works as normal in this way except the subwoofer and the no dependance state of the relay.
Now, as far as I can think thaqt I might have replaced the transistors in the protection circuitry ( using A1015 instead of C1518 i.e. NPN instaed of PNP) as I had to look after my small kid in between while doing this.
At this stage I have checked each and every component on the whole motherboard and evrything is fine ( I hadto replace a blown IN 4148 diode in the protection circuitry)
I am really stucked and frustrated and would really appreciated if someone can give some input on this or the best help would be if I can get the service manual or at least a schematic for it.
I have got this system from Australia and now I am staying in India and had to get it shipped here which costed a lot and repairing it would be my only option. I am not an very experienced repairer but have done some hobby projects and repairs being an electronics engineer.
Any help in this regard would be much appreciated.
Thanks in advance.