Help me troubleshoot an amp using STK461 chip

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I have aquired an amplifier with one working chanel, and one channel that seems to stick to one power supply rail (DC voltage). It uses an STK461 chip amp and the number and structure of the components inside looks relatively simple. Whilst i can aquire a replacement chip i am wondering what other tests i should run or common faults to look for before i go buying a chip that i don't need. Any pointers or links to tutorials etc?

An externally hosted image should be here but it was not working when we last tested it.


An externally hosted image should be here but it was not working when we last tested it.
 
There's very little externally to go wrong with these chips. The only thing I can think of is to check that the DC isn't coming from a preamp stage (eg a missing rail to one of the opamps). This is unlikely though.

It is likely the chip is damaged possibly due to a short on the channel. Replacing the chip is the most likely fix.
 
OK, i finally got around to replacing the chip, now both channels create sound from output, however the right channel has a distict, and relatively loud (and independant from volume controls) hum at 50hz (sounds slightly hasher than a plain hum, hard to explain). This suggests to me that it is something to do with the power supply, what should i be checking for now?
 
.....You can check to see if there is some electrolyte that might have leaked out of the bottom (near the rubber sealed side), or if there is an acrid odor. One channel hums and the other doesn't?? Hmmmm, is there a DC offset on the channel that hums? Is the gain the same between the two channels? If the "hummy" side has higher gain and there is a DC offset, you might want to check the negative feedback loops shunt leg capacitor.
 
Required help stk 4141

Hi all.

i hope somebody help me in the forum.
i am a begginer in electronics.i brought stk 4141 and circuit ,i am able to see line in 2 channels and line out 2 channels and grounding on the circuit but i am not able to see power input,can someone please help me in this please let me know how to where to connect power and volume controls and BT board,thanks in advance.

Thanks
Sagar
 
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