Hi guys...
I have this old amplifier kit from like 5years ago. The IC is broken so I replaced it. Its a Toshiba TA8205ah.
Somehow i managed to make it work. Monitored the IC temp, gets hot fast but i think the heatsink can handle it.
I powered it with a 12v 3A regulated power supply.
But after a minute i smell something, and then i noticed that the 10 Ohms 1/2W resistor gets extremely hot. That its color is almost brown already.
What could possibly be the problem? Somebody help plssss....
The image below is a part of the amp's schematic.
I have this old amplifier kit from like 5years ago. The IC is broken so I replaced it. Its a Toshiba TA8205ah.
Somehow i managed to make it work. Monitored the IC temp, gets hot fast but i think the heatsink can handle it.
I powered it with a 12v 3A regulated power supply.
But after a minute i smell something, and then i noticed that the 10 Ohms 1/2W resistor gets extremely hot. That its color is almost brown already.
What could possibly be the problem? Somebody help plssss....
The image below is a part of the amp's schematic.
Attachments
Any resistor series to pins 3 or 6, or a capacitor too small, could decrease the gain below stability margin. Also, those inputs reference ground (through a cap), and if the inputs were mixed up to reference your volume knob instead, that would do the same as a resistor, setting the gain low enough to go unstable.
The datasheet has a short in it at pin 4, which doesn't require endless current, but really should have a resistor, possibly 10k. All that pin needs is at least 3v, and very little current.
The cap at pin 8, is probably necessary to prevent fluctuations that would eat up the stability margin.
Likewise, a good cap (s) at pin 10 and 17 is probably necessary for the same reason.
Also check the power voltage--if it is too high, you'd need to eat up the excess voltage by adding a regulator circuit.
The datasheet has a short in it at pin 4, which doesn't require endless current, but really should have a resistor, possibly 10k. All that pin needs is at least 3v, and very little current.
The cap at pin 8, is probably necessary to prevent fluctuations that would eat up the stability margin.
Likewise, a good cap (s) at pin 10 and 17 is probably necessary for the same reason.
Also check the power voltage--if it is too high, you'd need to eat up the excess voltage by adding a regulator circuit.
It does seem like it's oscillating. What source are you using to provide a signal to the amp?
Another thought - recheck your solder connections and the connections of any parts around the replaced device.
If it's an electrical failure, whatever condition caused the original device to fail could still be present in the circuit.
Another thought - recheck your solder connections and the connections of any parts around the replaced device.
Was the IC physically broken? Like into two pieces? Or did it electrically fail?
If it's an electrical failure, whatever condition caused the original device to fail could still be present in the circuit.
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The IC got fried! So i replaced it. Now its working but with resistor temp too high. Also the Ic gets hi fast!
Those resistors should run cold. As others have said, the cause is that the amp is unstable and oscillating. Typical causes on a diy amp would be an incorrect grounding scheme.
It may be happen that another component in the circuit is faulty, or the new power IC is faulty, not as uncommon as it would be. Check the rest of the components in the PCB.
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