nad phono stage

[Chrisr3521]

hi i have an old nad 3020 that im currently restoring, it was in very bad shape, its all going well appart from the phono stage when i apply a sinewave to it, it turns it into a square wave, having not really dealt with phonostages before i was wondering if this was correct because the trace on my friends oscilloscope is the same for left and right at the pre-amp output, its just that its a square wave!

any help would be appreciated

thanks
chris

 

[leadbelly]

No it's not right, of course. What are the ranges for your input and output? Is your output range so low that it is clipping off the peaks?

 

[adason]

may be you are clipping it heavily

 

[djk]

Clipping?

For sure.

A phono input only handles a few mV (0.001V).

You also need an inverse RIAA filter to check response.