Boston Acoustic powered subwoofer wont power on

[NDogg6]

I picked up a home audio subwoofer that I can't get to power on. I am assuming it is a problem with the power supply. I have voltage coming off of the first board on the left but, nothing coming out of the boards on the right. There are no signs of bad components. Any ideas?

[mariushm]

Re: Boston Acoustic powered subwoofer wont power on

The board in the center looks like a mains filter, it's 110v coming in and filtered and going out through those poles in the back of the board.

You don't have anything connected to those poles in the pictures.

The board all the way to the right seems to be a switching power supply, I think the cable at the bottom right goes to the center board, and at the top of the board on the right you should have DC voltage.
If the boards on the right are connected to you have some voltage at the top?

Did you remove some heatsink from the board on the right? Looks like two ICs have some thermal paste on them and what seems to be something to screw a heatsink to.

What ICs are on that board on the left. If you find the datasheets for those, you may be able to determine what input voltage is supposed to be a test the subwoofer with a separate current limited power supply

[NDogg6]

Re: Boston Acoustic powered subwoofer wont power on

Yes, I removed the heatsink because I couldn't see all of the components clearly. When it is all connected, I don't any voltage at the poles or the connection at the top of the board on the right. When I disconnect it all, there is still power to the board on the right. I can watch it dissipating on my multimeter.

[Longbow]

Re: Boston Acoustic powered subwoofer wont power on

The board on the right is a switching power supply. You might get lucky checking for opens/shorts, but then you will want a schematic. Closeups of the power supply board itself, taken out of the unit, will help.

[selldoor]

Re: Boston Acoustic powered subwoofer wont power on

Can you put all the wires back in and post an overall straight down picture of it.
Can you also post a picture of the vertical board.
Can we take it that you have tested the fuse/s there is at one marked on the board second from right. May be under the board?

[budm]

Re: Boston Acoustic powered subwoofer wont power on

By the way, does it have the bypass switch to turn the unit on maually? Most sub-woofer will turn itself on when it detects audio signal, and goes into standby if the audio is not present for a period of time.
Model number of this unit?