![]() Predicted Closed-loop frequency response mute signal: muted high, about 2V to 34V allowed the SMD PCB is wave soldered, there are power traces filled with solder, the rigidity of so much solder around SMD multilayer ceramic capacitors increases failure rate when subject to vibration due to the AC coupling capacitor in the clock signal, clock failure makes the amplifier transition to phase-shift self-oscillation (at well above 150khz), frying output stage single component failure (open) results in destruction of output stage, for the case of too many of the components in the circuit crossover frequency of feedback loop: 80khz max. input signal: +/-7.4V for -/+70V output The high-level input seems to pass directly through the plate amp, to the passive crossover inside the cabinet, and on to the mid-bass/mid/tweeter.įrom the schematic provided and according to my calculations these are the specs of the "timed self-destructing module": The sub input comes in directly to the plate amp, then through an adjustable low pass crossover and sub level pot to the sub. ![]() The powered 10" sub and 12" PR are on the side of the enclosure, and the mid-bass/mid/tweeter are on the front. Apologies in advance if I'm missing any threads I should I have read - I did search high and low for previous threads about repairing these amps and found nothing.īelow are a bunch of pics of the speaker and the amp in question. I'm posting here hoping for some help and of course hoping to learn more about how Class D amps work and how I could go about diagnosing this on my own. Problem is - I'm a mechanical engineer, not an electrical engineer, so I'm a bit out of my league. Maybe one, maybe several components are underspec'd? Maybe it's the MOSFETs? Maybe something else. Given the routine failures, even of the replacement amps, I imagine there must be a design flaw in here somewhere. The company does offer a replacement service for mucho dinero and is unsurprisingly tight lipped about any faults / schematics or any help to DIY (no idea which company actually makes/supplies the amp). Searching online for these speakers yields numerous complaints (namely on the AVS Forum) that the OEM amp design fails routinely in couple-year intervals. The only thing that might bug you out when disassembling the subwoofer are the deep screw wells - you need a long and slender Phillips driver to get at the screws.I'm looking for help reverse engineering the Class D amp in a pair of Cambridge SoundWorks Newton T500 speakers I acquired in order to identify and fix any design flaws that may exist. We tested the speakers playing some Pink Floyd from the phone - all OK! The fuse in question is a 3.15A 230V, and I replaced it with a 2.5A 230V fuse one. Don't ask me why - in the mid 90s, some gamer probably played a too tough session of Doom or something. ![]() Immediately I saw that hidden beneath some 20 screws was a fuse that had popped. Since this kind of electronics in my experience rarely fail without some trace, I decided to open the subwoofer up and have a peek to see if there were any burnt components or loose soldering. Problem was that when plugging in the wallwart (12V), nothing happened. Anyway, what I had found at the store was an neat old 2+1 setup with a huge subwoofer and two satellite speakers. Way back in the PC history, Cambridge Soundworks made some neat PC sound systems. Cambridge Soundworks were later aquired by Creative. Fancy me finding one for USD 10 at the local thrift shop today! So all components are nearly there but I lacked a cheap dirty sound system for the setup. The game in question: Truxton by Toaplan. I am planning a birthday party for my oldest son, and thought I'd let the kids play some old-school arcade games using an old PC, a projector, a DIY joystick setup and some serious sound. Cambridge Soundworks SW310 from way back in the 90s ![]()
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