you can power that section of the PCB separately and test its functionality, typically there is a 4.7 ohm resistor that opens and a bunch of 470 ohm resistors that open.
Find ground and +5 volts that feed those 2 ic's. You will find the connections on the center terminal strip. You should see a square wave on the last pin of the center terminal . If I was home I could tell you exactly which pins. It is easy to figure out.
would that indicate that the complete module is working correctly? would it indicate if there were a problem with the driver transistors?
The driver transistor fail a lot, did you have shorted outputs? If you did, the AG and DF transistor go bad, and the 470 ohm resistors open.
What is the original problem?
What is the original problem?
tom i've tried to repair these modules several times but have not had much success with them, the boards that use the ir drivers are much easier to repair
I have had 100% success with them, only because I am a sadist, and I can't get a replacement.
Typically, the outputs short for various reasons, when they short, they take out the small drivers transistors. The 4 on each side. You can measure the 470 resistors and replace 1D and 2D s.
I have found the 4.7ohm resistors open, and another resistor in the drive circuit opens (cant remember the number off the top of my head).
If you replace all the parts and it doesn't oscillate, that resistor is the problem. I can look for the number when I get home.
That Lm211 and TL072 will oscillate if you power it up out of circuit, you can follow the square wave right to the bases of the 1D and 2D.
Typically, the outputs short for various reasons, when they short, they take out the small drivers transistors. The 4 on each side. You can measure the 470 resistors and replace 1D and 2D s.
I have found the 4.7ohm resistors open, and another resistor in the drive circuit opens (cant remember the number off the top of my head).
If you replace all the parts and it doesn't oscillate, that resistor is the problem. I can look for the number when I get home.
That Lm211 and TL072 will oscillate if you power it up out of circuit, you can follow the square wave right to the bases of the 1D and 2D.
i powered it up but dont get a square wave i get a triangle so would that be the resistor you talking about that goes open, i have found a lot of times the ag and dk transistors burn if the fets short
I assume that you checked those components already, and replaced, along with 470 ohm resistors.
If you have powered on the 2 IC's, you should have a square wave output on 2-8.
BTW, do you have a schematic for the amp?
If you have powered on the 2 IC's, you should have a square wave output on 2-8.
BTW, do you have a schematic for the amp?
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Wouldn't you have to have both positive and negative 5v connected as well as ground to get a clean square wave out of the op-amps?
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