[SOLVED] Amplifier System not Working

Hi guys I have a Zoltrix SW 85 woofer. At first it was working great and the sound was awesome. But one day it became dead i.e Amplifier IC was burnt due to overheating. My friend took it to the hardware shop and he installed a new IC. The woofer didn't work as before and after few days the main woofer started giving humming sound but the sound from two sub woofers was clear. As I increase the base the humming sound becomes more loud. Also at low volume sound is somewhat ok but as I increase the main woofer starts giving humming sound.

First I thought it is audio cable problem so I replaced the cable but the same problem.

Secondly I thought Amplifier IC must be defected so I again change it but it also didn't work.

I don't know what to do I have checked everything capacitors, transistors but I am not able to solve the problem.

Someone also told me that your main speaker is faulty but I wired the main woofer into sub woofer and it gives a smooth sound also I wired the sub woofer into main woofer it gives the same humming sound so it is cleared all speakers are fine.

It is simple woofer which is based on single Power Amplifer IC with some filter capacitors and Volume control IC. Can anyone help me?

I understand that you are talking about a background hum, present without sound played? Does it stop, when the audio cable is unplugged? Does t stop, when the computer is turned off?

Yes I think.Actually I am using new woofer and I lost my old woofer audio cable so I am not able to check right now but I am sure the humming sound only comes when something is played. I know you are thinking about line frequency pickup.

Hum is typical of an open (meaning bad) diode in a linear power supply.

The supply V can reach usable levels. But only sufficient for low volume. If the volume gets loud then the ripple (hum) starts getting worse.

There's also the case of a shorted diode in the power supply. This tends to blow a fuse somewhere. However you don't say a fuse was blown. But even if a diode partially fails you still are likely to get hum.

You might have a bad diode as a result of the amplifier IC going bad, or else vice versa. You say you checked all the other components.

You'll have to test each diode individually. You'll have to take each one out of circuit by clipping one of its leads. Then when finished you'll solder the leads back together.

I agree with BradtheRad. If the hum appears only under "load", it's most likely a power supply problem. It would be still line frequent hum.

Thank you guys for your great help.

is it worked well ?

Well I didn't check yet but I think BradtheRad got the point.