[Excalibur]

I have a Harman/kardon 19.5 speaker system and the amp. is broken. (I think.)

On power on, i have to put my ear right next to the speaker only to hear a 50Hz buzzing noise.
On power off, i hear a scraping, grinding noise that moves the speaker about 2-3mm.
The left speaker works fine.
The right channel is the one with the problem.

Leaving the unit on for a minute makes the chip heat up many times hotter than it ever should.

Any help on whether it can be "fixed"or not?
If not can I disconnect the right channel power part of the chip so it doesn't heat up?

Any help greatly appreciated.




Note: I used to dismantle things when I was young and try and "fix" things that weren't broken.
          The parts of the circuit board with the volume and treble controls is now replaced with wires since the thin copper strips peeled off due to excess heat from my soldering. I now wish I'd never opened the unit, but I learn't things from it, so....

I will either get a new chip if I can get one or a new unit.

All this assuming the chip has a fault, not a capacitor or resistor, etc.


 

[Mika]

I happen to know someone who knows something about amplifiers, so I can refer your problem to him if you want.

Mika

[castor]

On power on, i have to put my ear right next to the speaker only to hear a 50Hz buzzing noise.
On power off, i hear a scraping, grinding noise that moves the speaker about 2-3mm.
The right channel is the one with the problem.

Do you get this with the right channel input short-circuited? If not, have you made sure that your source is not at fault?

If not can I disconnect the right channel power part of the chip so it doesn't heat up?

Doesn't look like that according to this: http://www.datasheetcatalog.com/datasheets_pdf/T/D/A/2/TDA2007A.shtml
Tough, you could try if disconnecting the output (pin 7 or 9) helps any.

[Davros]

19.5 speakers - is that enough ?

[Excalibur]

@ Davros:    :wtf:Uh.... I assume you know it doesn't mean 19.5 speakers literally?


@castor - its not the source , since it is a mono jack I incorperated into my clock/radio and I've plugged something else into it and it worked. The left channel speaker works fine so the fault must be in the circuit board.


@ Mika: that would be greatly appreciated - thanks

[G0atmaster]

it sounds to me like you need to find someone with some soldering experience, a magnifying glass, and a good electronics parts dealer to resolder some burnt parts on the circuit board.  That's pretty characteristic of something definitely blown.  I don't know TOO much about the inner workings of amps, although I am a sound guy.  I know someone who's got a couple of degrees in Electrical Engineering areas, I'll ask him about it.