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Class D Switching Power Amplifiers and Power D/A conversion

B&W ASW 675 amp module repair
B&W ASW 675 amp module repair
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Old 18th October 2011, 11:37 PM   #1
soerboe is offline soerboe  Norway
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Default B&W ASW 675 amp module repair


I recently got my hands on a faulty B&W ASW675 amp containing a 500W Class D amp module. However, the amp does work. I've heard that there were some problems with these amps, so I was wondering if anybody of had any experience with this particular amp?

The amp powers up with the auto on/off kicking in, but there's not sound at all from the speaker. I've started some light testing, any many of the lrage capacitors contain voltage after the amp has been swiched on and off. Any troubleshooting tips for class D designs? Perhaps somebody has a service manual?

I've done a thorough visual inspection of the four PCBs, but I can't see anything wrong. I'm fairly new to class D amps, and repairs in general, so any help would be greatly appreciated!

I can post pictures if required.

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Old 19th October 2011, 12:32 AM   #2
abraxalito is offline abraxalito  United Kingdom
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I just visited the B&W service site and downloaded the service manual they have there for the ASW675. It contains no information at all about the amp module.
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Old 19th October 2011, 06:56 AM   #3
wimdehaan is offline wimdehaan  Netherlands
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Default B&W ASW 675 amp module repair

The new B&W subwoofers do use B&O Icepower modules, this 675 series seems to use Philips technology.

I found the following text in some advertisement regarding the 675 series :

With development help from Netherlands based Philips, the new 500 watt "Class D" amplifier provides plenty of headroom while the other supporting electronics include a continuously variable crossover with two-way crossover filtering (providing third-order 80 Hz high-pass "returns" on its line-level outputs), and unique A/B bass-rolloff switch with two distinctive filtering curves. The ASW-675 is offered in black ash, and "sorrento" light oak woodgrain exteriors. Their new ASW-CM incorporates extensive bracing and if offered in real-wood veneers including rosenut, maple, and black ash finishes.

Amplifier module uses an integrated switched power supply.
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