Microlab Solo 9C active Speakers audio cutting out when volume high

[funkster]

Hi Guys,

At the moment just want some advice on what might be the problem without opening up and exposing the internals of these speakers. Just today they started failing for me, they're almost 3 years old in around 4 months from today.

Whenever I turn up the volume the audio starts cutting out, especially on the sound of the beats happening. They're an all in one speaker set with and inbuilt amp in the right speaker. I've tried different inputs and different sources both analog and digital, they're all the same. The same audio that plays on the TV is okay and doesn't cut out but not on the speakers. What could be causing this?

I think my warranty has run out but not sure yet so I may just open it up and take photos of the internals soon.

This is the link to the speakers I have http://www.microlab.com/?r=Stereosys...st=full&id=693

[Andrew F. Ali]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Probably an e-cap in the power supply or dry joints on the circuit board/s or perhaps in the power amp section.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So it looks like you have a HDMI output. Does this output work when you turn up the volume?

[funkster]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So it looks like you have a HDMI output. Does this output work when you turn up the volume?

Yep, HDMI output is fine, both picture and audio coming out of the TV doesn't cut out or anything when volume is turned up, only the audio from the speakers cuts out.

[funkster]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Okay so I opened it up and connected the internal speaker wiring that goes from the crossover to the speakers to the outside banana/screw sockets that would normally send audio to the left speaker and turned it into a passive speaker as a test. I connected an external amp and both speakers are fine, no audio cutting out at all. So at least the drivers and crossover circuits have no issues. The problem lies somewhere else, possibly amp? or power supply?

Going to post some photos but it's difficult to take a few. I only managed to remove the power/amp board and RCA/SPDIF boards but still took photos of the others inside.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Okay so I opened it up and connected the internal speaker wiring that goes from the crossover to the speakers to the outside banana/screw sockets that would normally send audio to the left speaker and turned it into a passive speaker as a test. I connected an external amp and both speakers are fine, no audio cutting out at all. So at least the drivers and crossover circuits have no issues. The problem lies somewhere else, possibly amp? or power supply?

Going to post some photos but it's difficult to take a few. I only managed to remove the power/amp board and RCA/SPDIF boards but still took photos of the others inside.

If you turn the right speaker all the way on with the balance control and turn up the volume all the way does it do it and then if you do the same for the left speaker does it do it? That should tell you if it is before the power amp or after the power amp. The balance control should be at the pre-Amp stage. You could also have a dead spot on the volume control potentiometer.

[funkster]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Okay here are some pictures. One of the two big 6800uF 35V caps seems to be buldging out on the top a tiny amount but the photo doesn't show that even though I tried a side on view. I took off the heatsink of what I think is the amp section? Looks all integrated.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Okay so I opened it up and connected the internal speaker wiring that goes from the crossover to the speakers to the outside banana/screw sockets that would normally send audio to the left speaker and turned it into a passive speaker as a test. I connected an external amp and both speakers are fine, no audio cutting out at all. So at least the drivers and crossover circuits have no issues. The problem lies somewhere else, possibly amp? or power supply?

Going to post some photos but it's difficult to take a few. I only managed to remove the power/amp board and RCA/SPDIF boards but still took photos of the others inside.

So I see from here it has no balance. http://gadget-help.com/quick-review-...rolab-solo-9c/


It does have right and left input this way you can plug one in at a time and turn the volume all the way up. You will need to connect both speakers. So try one line then the other. You can also very the treble and bass to there extremes as you are doing this

[budm]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

https://www.badcaps.net/forum/attach...9&d=1487385097
Class D amplifiers and linear power supply (Transformer output for the power amp: 21-0-21 = about +/- 30VDC supplies).
Did the heatsink for that IC get very hot?
Company claim 70W RMS.
Try running the speaker with the back open to see if it will work without cutting out.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So what I see is two places I circled in red. One looks like leg is cold soldered. The other part looks damaged. In the Yellow circle it looks as if a wire on solder bridge shorting out the capacitor.

[budm]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So what I see is two places I circled in red. One looks like leg is cold soldered. The other part looks damaged. In the Yellow circle it looks as if a wire on solder bridge shorting out the capacitor.

Good eyes!

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So is this where you right and left speaker are connected that I have circled in pink.?

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Good eyes!

Hard to tell if what I see is really there.

[budm]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So is this where you right and left speaker are connected that I have circled in pink.?

They look to be it, 'L', 'R' marking, those two inductors and caps are for the filter for the output, it is not inductor-less Class D design.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

BudM I would think this is the amp board? But it seems to be the pre-Amp. The power supply board seems to have the class D Amp on the back of it where the heat sink was?

[budm]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

That is the signal processor board.
This speaker system has Linear power supply and power amp all in one board.
It is Class D amp setup.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

That is the signal processor board.
This speaker system has Linear power supply and power amp all in one board.
It is Class D amp setup.

Is that a little crazy to do?

[budm]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Speakers look good from the out side, I believe they sell them for > $400.
Every things are inside so the heat is just trapped inside the cabinet, most powered speakers will have heatsinks exposed out in the back plate.

[keeney123]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

Speakers look good from the out side, I believe they sell them for > $400.
Every things are inside so the heat is just trapped inside the cabinet, most powered speakers will have heatsinks exposed out in the back plate.

I just wonder about the power supply interfering with the power amp. The power supply would have AC voltage on it. I know on class D amps they are worried about EMF. They even try to keep the speakers as close to the Amp as they can because of this interference.

[funkster]

Re: Microlab Solo 9C active Speakers audio cutting out when volume high

So what I see is two places I circled in red. One looks like leg is cold soldered. The other part looks damaged. In the Yellow circle it looks as if a wire on solder bridge shorting out the capacitor.

What does cold soldered mean? Also I tried to take a close up shot of that area on the board.