doctorq wrote:
But I have a problem with my audio sockets. The sound is very low when I use the PSU from the Tower, but when I use my original PSU from my A4000 desktop, there are no problems. Have anyone done a hack on this tower, to make their audio listenable?
I had this exact same problem with my Power Tower MK-II and sound. It took an entire day of searching for it with multiple disassemblings and re-assemblings involved. My dealer (Raymond Computer in St. Paul, Minnesota) tore down the machine all the way to replacing the motherboard with a spare board at least four times. The problem happened every time, even with changing the motherboard. Finally, the girlfriend of his (Ray, the owner of Raymond Computer) son, who happens to be quite adept with electronics, suggested that the grounding for one of the power sources could be gone or intermittent.
Sidebar: Sound from the Amiga motherboard is produced by operational amplifiers (Op-Amps). The Amiga sound Op-Amps require both + voltage and (-) voltage, with their respective grounding, in order to work properly. So, after the final disassembly and re-assembly, Ray and I started tracing power lines on the motherboard.
Back to the main story, and the solution. It turns out that the -12 volt
ground line was 99% intermittent on my motherboard. Very rarely sound would work properly, but usually it would not. We traced the intermittence all the way back to the main motherboard power connector. It's the rectangular one with either six or eight wires (I think six). The connector provided from the power supply in the Power Tower MK-II is a cheap piece of plastic junk. The wires in the connector, if they encounter any resistance, can be pushed backwards out of the connector itself if it's being plugged in awkwardly (i.e. not pushed exactly straight in). That would cause the wire itself to not be physically connected to the motherboard.
Since your computer otherwise works normally with the exception of the sound, most likely your -12 volt ground line has become disconnected like mine did. Here's another tidbit of information. The sound and the Amiga motherboard built-in serial port are linked to the same -12 volt power and ground lines. If your sound doesn't work, then your built-in serial port should not work either, or it will be very unreliable. Even the parallel port might be affected, too, but I'm not sure on that one. I don't know how reliable of a test that is, but on my machine, the serial port did not work at all either along with the sound. Once I fixed the -12 volt ground problem, both the sound and the serial port are working again.
To sum up, disassemble your Power Tower MK-II down to the point where you can get at the main power connector for the motherboard. Use a pair of needle nose pliers to grab onto each of the power connector's wires individually. Gently wiggle and shove the wires back into the connector (and, hence, back into the motherboard receptacles). Make sure you don't slip and bounce the pliers off the motherboard itself cause you might damage something if you do. My bet is that you will feel and see one of the wires moving into the connector/board farther than the others. If so, then that's likely the cause of your sound problem. Re-assemble the tower and give it a try.
Please let us all know if the above information helped you out. Thanks! :-)
