Noise On 2.1 Speaker after replacing Transformer

[Nilesh]

Hi Guys , i have sent my Speaker for repair which was eventually not turning on . When I went to take it , the guy told me they changed the Transformer .
But Now When i turned it on , there is Hum Sound .
Its Present in the subwoofer also Even if i removed the Left And Right Speakers too .Anyone can tell me What To Do ?
Speaker is A Microlab M300 40W
And Using 2 Prong Power Plug

 

[TLS Guy]

Hi Guys , i have sent my Speaker for repair which was eventually not turning on . When I went to take it , the guy told me they changed the Transformer .
But Now When i turned it on , there is Hum Sound .
Its Present in the subwoofer also Even if i removed the Left And Right Speakers too .Anyone can tell me What To Do ?
Speaker is A Microlab M300 40W
And Using 2 Prong Power Plug

Well I'm pretty sure the tech made a mistake. He may have inadvertently created an Internal ground loop or forgotten to connect a ground. Take it back to him, and make him fix it without leaving you with a hum.

Just because the unit is two prong, it will still have an internal ground plane.

 

[Nilesh]

I have opened the Subwoofer Unit , Inside There is a bigger Transformer , than the original one onboard (which is fried) . Can you suggest how to set a ground on the transformer ?
The Output Have Three Cables Red , Black , Red .
If anyone can tell my how to ground it . I can do it.
Its just that my warranty is over upon this unit .

 

[TLS Guy]

I have opened the Subwoofer Unit , Inside There is a bigger Transformer , than the original one onboard (which is fried) . Can you suggest how to set a ground on the transformer ?
The Output Have Three Cables Red , Black , Red .
If anyone can tell my how to ground it . I can do it.
Its just that my warranty is over upon this unit .

No, you can not fix this. It will take instruments including an o-scope to analyze this to see what is going on. It won't just be a matter of grounding the transformer anyway.

The fact is this unit was improperly repaired. After a warranty repair it was returned to you not working properly.

The fact that a different transformer was used, I suspect means they undersized the original.

I now suspect that the new and bigger transformer is radiating a bigger AC magnetic field into the higher gain circuits. So the answer would then be a higher quality transformer with less external field radiation, or a different location on the board.

You need to contact the manufacturer and complain mightily. If they won't give you satisfaction then you will have to bite the bullet, junk that sub and get a better one.

I strongly suspect that the sub was improperly designed and there is no adequate fix for the problem they created.

I looked at that unit on line. It just looks like an absolute POS. I would expect it to go wrong.

My final and probably most important recommendation to you is to absolutely swear off buying junk like that. Cheap junk is always the most expensive route. Next time choose classier gear.

 

[Nilesh]

Thanks A lot for the kind approach buddy, no one would have given me these details .
Indeed , its cheap but it was a new brand here , thats why i bought it :/
Ok, i will swap it for a new one . Thanks Once again