BFE DV1175 - no output

I bought a DV1175 summing amp but after a first test there is only very low output (40 or 50dB less than the input signal) and no bass in the output signal on both channels.

For the test I connected my converter output to the "Eingang entkoppelt" and the output of the amp to the converter input. When tracing the signal with an oscilloscope the last point I can measure the signal is the inverting input of the first opamp (pin 7), there is no output on pin 10.

This would tell me that the first NE5533AN is the problem, BUT both channels have the same problem and the bass roll off is already measurable on the input of the chip - which makes a faulty chip unlikely.

Does anybody have another idea what might be the problem?
I don't have the chips here so I can't just throw in a new one and see.
Voltages are fine btw....

Anybody?

Sounds like you have only connected one leg of the signal, thus giving a typical transformer lack of bass and low level. Connect as a balanced input signal to both legs from the balanced output of your converter. Then trace using a multimeter to prove both legs are connected, and check that the transformer primary is present.

radardoug said:

Sounds like you have only connected one leg of the signal, thus giving a typical transformer lack of bass and low level. Connect as a balanced input signal to both legs from the balanced output of your converter. Then trace using a multimeter to prove both legs are connected, and check that the transformer primary is present.

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Thanks for your reply!
I just did another test: both hot and cold are connected to the input. I traced the signal and it's there on the input of IC1 (pin 7) but gone on the output (pin 10).

Like I said, I would usually change the IC, but NE5533ANs are pretty hard to get...

andow said:

Like I said, I would usually change the IC, but NE5533ANs are pretty hard to get...

Click to expand...

I can send you 4 pcs for free. You should pay the shipping from Croatia to Austria (about 7Euro).
If you are interesting, PM me your shipping address.

Make an adapter PCB with header pins that match the NE5533 layout and a DIP socket for a standard dual op amp. OSH park is cheap for small adapter boards like this although I would choose the thinner PCB run which might take a little longer.