BOSE Acoustimass 300 Bass Module

[sikocan]

The device has no Orange or Green LED when power plugged in. I've checked the famous DIODE issue - it's good, I've replaced it anyway - same issue. I've attached relevant pictures and measurements for reference. If you need more details - let me know - what do you recommend I check next?

Google Drive for more pictures and details: https://drive.google.com/drive/folde...usp=share_link

Thank you

[MasterCap]

Re: BOSE Acoustimass 300 Bass Module

So what does it do when plugged in and turned on, any voltages at all? Does it have STBY power, like a 5V rail, and some LED is powered from that ? It could be from a mini-SMPS, or just a linear regulator.

I'd see if there's Stby power, and then I'd look up the controller chip datasheets, and see if they get power, and if they have enable and/or power-good pins, see what they are doing.

Now I have an isolation transformer, and a series light bulb, so that even if I did something bad like short something with my DMM probe, I'd not get killed as easy or blow up something.

So personally, with it unplugged, I would check the input path from the plug, into the mains rectifier, see where it splits from there, like to a STBY rail or not. And then I'd solder on a few wires, for easy/safe probing. See what the voltages are on the main input cap, and if the secondary output voltages are there. And if not, I'd check the gate drive on mosfets, see if they are being told to run, or if something around them is broke. And then see what the controller chips are doing.


That great big black cap in the middle, is could be fed by a boost converter, that would basically double the mains rectified voltage, when working. There's a big coil/inductor just to the right of that main cap. That could be a booster converter stage.

But it may not be that. The other big transformer, right below the cap, should be the main step-down transformer, or it could be another secondary stage, taking say 12V to 5V.

So anyways, for anyone reading, the main big cap after the rectifier, could have 170V on it, but unless you know the layout of PSU, it could just be in standby, and if it was working, have 340V on that cap.

So also check the voltage rating on that main cap, as a clue to if has a boost converter stage. They are basically in parallel, between the main's rectifer, and the main step-down inductor/transformer.

That little transformer off to the upper left, is probably the gate drive transformer for the main mosfets. Or it could be standby power.

[sikocan]

Re: BOSE Acoustimass 300 Bass Module

Hi mate, while I'll read your post shortly, here are some voltages.

[sikocan]

Re: BOSE Acoustimass 300 Bass Module

I have only a series light bulb, which is setup as follows.

[sikocan]

Re: BOSE Acoustimass 300 Bass Module

Finally 😎

[rvazquez0102]

Re: BOSE Acoustimass 300 Bass Module

Hi sikocan,
I have a Bose Bass Module 700 that does not turn on. I would really appreciate if you could tell me how did you finally solve it for your device?
Thanks in advance for your support.
Regards,

[sikocan]

Re: BOSE Acoustimass 300 Bass Module

Search on my channel on YouTube SureCanDo Computers

[Jokerbojan]

Re: BOSE Acoustimass 300 Bass Module

Search on my channel on YouTube SureCanDo Computers

Hello sikocan, I have the same problem with the bass module 300. Please tell me how you finally solved your problem? Thank you. I'm watching your YouTube channel but I didn't find the video.