Eton PA 5402

[Perry Babin]

You stated that the op-amps have 47v. Which is right, 21 or 47?

What if you place your black meter probe on the RCA shield?

 

[Achim1409]

47V on the op amp, 21v on the regulator

 

[Perry Babin]

You mentioned the 317 regulator and the op-amps together so I assumed that the regulator was for the op-amps. What's the regulator for the op-amps?

 

[Achim1409]

i expect this 317. There is no other. Also no circuit like in the diagram for the clarion. Only left the 3-pin shunt. But there is also no direct connection.

 

[Achim1409]

Does anybody have a diagramm for the power section for the op-amps? If i remove U8 (red circle), one by one op-amps are blown. U8 could be a shunt regulator. I want to now, how the Voltage is generated for the amps, and how much voltage it should have. If i connect the black lead to bat - and the red lead to the op-amp i measure on + 25VDC and on - 23VDC.

 

[Perry Babin]

What's the part number on the face of the regulator?

 

[Achim1409]

TL431HC

 

[Perry Babin]

That's definitely a shunt regulator.

Are the resistors used to set the regulated voltage within tolerance? Consult the datasheet to see their connection if you're unfamiliar with this regulator.

 

[Achim1409]

Iam not familiar with this circuit, thats why i asked for a diagram, which is nearly same layout.
Found a Potentiometer close to the regulator. Its set to minimum 23,4V. I can increase the voltage with this potentiometer.
Iam not sure, but there are also some BA4558 installed, the max voltage in the datasheet ist +-18V, so i expect that the output of the regulator is still to high.

 

[Perry Babin]

Did you look up the datasheet? It explains how the IC works. It's essentially an op-amp with a 1.5v internal reference on it's inverting input.

 

[Achim1409]

Yes, found it. Seems everything ok, all resistors in tollerance. Only one OP amp gets hot. From somewhere i get 25v on Pin 2. I have to search this Problem.