Teufel Concept E Magnum PE - Subwoofer loud buzzing

[Capacitorial]

Hello Badcaps-Forum,

I got a Subwoofer (just the Sub) and found out that after powering it (without speakers connected) the Subwoofer is very loud and buzzes or puts out loud continuous bass sound. If I disconnect the sub from the inside (the two cables on the membrane) and connect only the speakers, everything is fine and music plays normally.

What can be the issue here? This is the PCB of the subwoofer amplifier since the fault has to be there: https://imgur.com/a/YgbZZ6O

One of those big caps feels more bloated than the other. Should those be completely flat, cause I can feel that they are slightly bloated at the top.

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

no pic in link

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

The link contains a picture now. Sorry for that. I also scraped of some of that weird "glue" (?) and uncovered some resistors under it. These were still good.

https://imgur.com/a/x7SfT5i

[RJARRRPCGP]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

One of those big caps feels more bloated than the other. Should those be completely flat, cause I can feel that they are slightly bloated at the top.

Sounds like loud utility AC-frequency buzzing to me! I think it's safe to say bad caps!

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Alright. I will try to find those 6800uF 63V capacitors, replace them and come back to bring some good news (hopefully).

[Per Hansson]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Get rid of all the glue, it becomes conductive.
And check the legs of wires and resistors covered by glue: they might be corroded and damaged.
For example that big power resistor: one leg looks green on it!

[budm]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

get rid of all the glue, it becomes conductive.
And check the legs of wires and resistors covered by glue: They might be corroded and damaged.
For example that big power resistor: One leg looks green on it!

+1

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

So guys, I am back with news. I changed the Capacitors and nothing changed. But I found out that the transistor A1941 (top right big transistor) is overheating. Changed that one too without positive result.
If I disconnect the subwoofer cables (red and black sitting on the speaker) it doesn't overheat.

Resistance of the subwoofer speaker was at 3.6Ohm. The cables that connect onto the subwoofer have 38.6V or something. What can be the reason.
Also if I connect everything and measure the voltage on the sub (with the cables on it) it doesnt have the 40V.

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Update: I changed all other capacitors too, without a positive result. Now I really don't know what to look after. Is the speaker itself faulty? What else can I check? Can the other board be a problem?

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

if you removed the glue it leaves transistors .
how many volts does it run on the rails .

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

The connector with three cables (yellow, black, yellow) that connects to the pcb has 31V between yellow and black and 63V between yellow and yellow.

I don't understand what the first sentence means.

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

make sure the glue is removed as it can become conductive .

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

I did without a positive result. Now it looks like this:
https://imgur.com/a/qMt4e6Z

Now I literally don't know what else I can do. The other PCB is not for the Subwoofer, but for the satellites/speakers, so I guess it is ok since they work properly.

Another experiment I did was to connect the cables of a sat to the subwoofer "replacing the sat with the sub-speaker" and there was music coming from it quietly. So I guess the sub speaker itself is ok (with 3.7Ohm).

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

you could test all the transistors

[mmartell]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Try flexing that board with the butt end of a pencil or similar while it's buzzing to see if you have a dodgy joint.

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Update:

- I measured all resistors on the PCB and they are all good and have the right value.
- I tested the transistors and they are all good.

So basically I tested every single component on that board and replaced all capacitors.

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

can you record the sound and post it ?

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

The sound is now different like in the attached audio file. You got to turn up the sound a bit. My mic couldn't catch it like it is in real life. It is a bit louder than that.
At first there was loud buzzing. Then after I cleaned the glue, there was no buzzing but also no other sound. Now after all the replacements (Transistor A1941, and all caps) with further cleaning, there is a quiet whining going on. There is no audio source connected. Just the Sub by itself.

[petehall347]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

check over your work . maybe a short or broken wire etc .

[Capacitorial]

Re: Teufel Concept E Magnum PE - Subwoofer loud buzzing

Ok I will check again.

I did test the speaker again by directly connecting a 9V battery to it. The speaker moved and made knocking/cracking sounds. So 3.7 Ohms and this test should be enough info to be sure that the speaker must be ok.