Eton PA 5402

[Perry Babin]

Is the voltage swinging positive or negative?

 

[Achim1409]

negative

 

[Perry Babin]

What happens if you pull Q3?

 

[Achim1409]

i just pull the negative end of d6. The amp powers up with green light.

 

[Perry Babin]

Is that diode leaky?

 

[Achim1409]

It seems the diode is broken. From both sides i have 110 with diode check. Can i use for testin an 4148?

 

[Achim1409]

changed the diode with another one. powering up. maybe this was the only problem?

 

[Achim1409]

put the other transistors back. Still powers up. Insane. Thank you so much perry. i will order the other parts and then tell you if working everything.

 

[Perry Babin]

It could be the problem. Working back one stage at a time can save a lot of guesswork.

 

[Achim1409]

What is this for a Transistor? Its marked on the board with U2, looks like a standard small transistor and has marking:MSC 6431AC 0249A icant measure any resistance, also my tester shows now component detected.

 

[Perry Babin]

I'm not sure what it is but a 431 is a shunt regulator. Look up the datasheet for a TL431. I'd suggest that you stop using that component tester and learn to test components with a multimeter.

 

[Achim1409]

it seems, that it is the part. With Multimeter on diode check it was possible to measure some values, so i think its still ok. Mostly i take my multimeter to measure inside the board. The tester is for me good to used if i want to match fets, and last check of transistors if they are realy show good values.

 

[Achim1409]

next step. Now iam checking the op-amps. If i measure between Pin 4 and 8 i have about 42V DC. This should be to much for the amps. The Powersupply is different as in the Orion. I have only one Positive Voltage regulator (KA317) if i measure between ground and the output i have 21.2VDC. It seems that the Voltage on the op-amp is double the voltage of the KA317. Any suggestions?

 

[Perry Babin]

Is the amp malfunctioning in some way?

 

[Achim1409]

yes, some of the op amps are dismounted, because they are exploded and full open. I think i repaired both channels. with a load on the outputs connected i have 0Vdc. But the red light is still flashing, but this time only every 5 seconds. Sometimes only the green lamp lights.

 

[Perry Babin]

Do you see the .same type of supply voltage (no negative, all positive) on all of the op-amps?

If so, is the negative supply directly connected (0 ohms) to the RCA shield ground or to the secondary center tap?

 

[Achim1409]

All Op´s have 47VDC. If i measure from Pin4 to RCA shield 2,3k, from Pin8 to RCA Shiel 1,1k. Center tap is no connection. Only to the Railcaps connection. Pin4 to + 2,3k

 

[Perry Babin]

On the Audio Troubleshooting page item #25, plug the values of the programming resistors on the LM317 to see if it's supposed to have 47v.

Does the resistor shown as being grounded in the image go to the shield or secondary ground?

 

[Achim1409]

The Resistor is connected to RCA Shield. I measure 0Ohm. With the measured Values i got 8,2V. I will try to see the rings.

 

[Achim1409]

So if i correct, it should be 17,2VDC. I measured about 21VDC. I think its still ok.