Adam A8 Subwoofer not working…?

[nuryev]

Hi,

I have an Adam A8 subwoofer that shows no signs of life when powered up.

Looking at the pcbs on the amp plate, some obvious signs of heat stress are visible. Can anyone with experience provide suggestions to get this subwoofer working again.

I have experience soldering and desoldering tth and smd components and although I have no technical training I look forward to any advice.

I have attached some pics, hope they are useful.

 

[as_audio]

Did you check the white fuses (first picture) ?

 

[nuryev]

Yes. Both seem to test good.

 

[as_audio]

Next check supply voltages

 

[nuryev]

Where do I start?

 

[as_audio]

Your pictures do not allow any useful advice here.

 

[nuryev]

Ok. More pics coming up. Thanks 🙏

 

[nuryev]

Pictures of complete plate amp component side, including close-up of sections old psu.

 

[nuryev]

Hope they are helpful.

 

[nuryev]

Amp pics to follow.

 

[as_audio]

This is not a beginners repair project.
Switch mode psu with mains input and about 320 volts dc after rectification.
I am not sure I should give any advice because of safety considerations.
The supply is different from the A7 schematic that you have.

 

[Nisbeth]

The amp is an ICEpower 200ASC module (manual of connections available online). I would suggest you do the following:

• 1) Check the amp for "signs of life" (measure the supply voltages on the "hanger connector" and the AUX supply voltages). If these are not OK, the amp is dead and should be replaced.
• 2) If the amp is OK, disconnect the front end and test if you can get sound by connecting a source directly to the input of the amp. If so, the problem is that the front-end board doesn't power up the amp.

EDIT: Note that the ICEpower amp is set up to be activated by the signal, so when doing the test in 1) you need to ensure that it isn't in standby-mode.

 

[nuryev]

Amp pics are attached.

 

[Nisbeth]

^ that is the front-end PCB (active filter etc.) The power amp is built into the other board 🙂

 

[nuryev]

Oops! Apologies for the oversight.
Thanks for enlightening me Nisbeth. I have worked on a Mackie SRM 1801 sub with the psu and amp on two separate boards on the plate-no Mosfets etc.

The amp is an ICEpower 200ASC module (manual of connections available online). I would suggest you do the following:

• 1) Check the amp for "signs of life" (measure the supply voltages on the "hanger connector" and the AUX supply voltages). If these are not OK, the amp is dead and should be replaced.
• 2) If the amp is OK, disconnect the front end and test if you can get sound by connecting a source directly to the input of the amp. If so, the problem is that the front-end board doesn't power up the amp.

EDIT: Note that the ICEpower amp is set up to be activated by the signal, so when doing the test in 1) you need to ensure that it isn't in standby-mode.

Are you able to provide a link to the manual of connections?
Thanks.

 

[Nisbeth]

https://icepoweraudio.com/products/other/asc-series/ (200ASC datasheet)

 

[nuryev]

This is not a beginners repair project.
Switch mode psu with mains input and about 320 volts dc after rectification.
I am not sure I should give any advice because of safety considerations.
The supply is different from the A7 schematic that you have.

Yes. I am aware of the risks. I gained some (limited) experience with switch mode psu in Mackie and home AV subwoofers, as well as studios equipment such as TC electronics Effects modules psu and RME fireface. I do appreciate your concerns and will take the utmost care when testing.

 

[Nisbeth]

I just reread the datasheet and what I would do is remove the small two-pin connector (the auto-on/off one) and short the two pins together on the ICEpower module. That should ensure that it starts up fully-powered on (assuming it does start up of course).

EDIT: Note that the ICEpower amp is set up to be activated by the signal, so when doing the test in 1) you need to ensure that it isn't in standby-mode.

 

[nuryev]

Thanks Nisbeth. I will familiarise myself with the data sheet and block diagrams before starting any tests, and will report back.

Thanks again.

 

[Toaster79]

I'd start about here. That diode is blown.